title: Electric motor

text: In 1886, Frank Julian Sprague invented the first practical DC motor, a non-sparking device that maintained relatively constant speed under variable loads. Other Sprague electric inventions about this time greatly improved grid electric distribution (prior work done while employed by Thomas Edison), allowed power from electric motors to be returned to the electric grid, provided for electric distribution to trolleys via overhead wires and the trolley pole, and provided control systems for electric operations. This allowed Sprague to use electric motors to invent the first electric trolley system in 1887–88 in Richmond, Virginia, the electric elevator and control system in 1892, and the electric subway with independently powered centrally-controlled cars. The latter were first installed in 1892 in Chicago by the South Side Elevated Railroad, where it became popularly known as the "L". Sprague's motor and related inventions led to an explosion of interest and use in electric motors for industry. The development of electric motors of acceptable efficiency was delayed for several decades by failure to recognize the extreme importance of an air gap between the rotor and stator. Efficient designs have a comparatively small air gap. The St. Louis motor, long used in classrooms to illustrate motor principles, is inefficient for the same reason, as well as appearing nothing like a modern motor.


title: Electric motor

text: Electric motors revolutionized industry. Industrial processes were no longer limited by power transmission using line shafts, belts, compressed air or hydraulic pressure. Instead, every machine could be equipped with its own power source, providing easy control at the point of use, and improving power transmission efficiency. Electric motors applied in agriculture eliminated human and animal muscle power from such tasks as handling grain or pumping water. Household uses (like in washing machines, dishwashers, fans, air conditioners and refrigerators (replacing ice boxes)) of electric motors reduced heavy labor in the home and made higher standards of convenience, comfort and safety possible. Today, electric motors consume more than half of the electric energy produced in the US.


title: Electric motor

text: In 1824, French physicist François Arago formulated the existence of rotating magnetic fields, termed Arago's rotations, which, by manually turning switches on and off, Walter Baily demonstrated in 1879 as in effect the first primitive induction motor. In the 1880s many inventors were trying to develop workable AC motors because AC's advantages in long-distance high-voltage transmission were offset by the inability to operate motors on AC.


title: Electric motor

text: The first alternating-current commutatorless induction motor was invented by Galileo Ferraris in 1885. Ferraris was able to improve his first design by producing more advanced setups in 1886. In 1888, the "Royal Academy of Science of Turin" published Ferraris's research detailing the foundations of motor operation, while concluding at that time that "the apparatus based on that principle could not be of any commercial importance as motor."


title: Electric motor

text: Possible industrial development was envisioned by Nikola Tesla, who invented independently his induction motor in 1887 and obtained a patent in May 1888. In the same year, Tesla presented his paper "A New System of Alternate Current Motors and Transformers" to the AIEE that described three patented two-phase four-stator-pole motor types: one with a four-pole rotor forming a non-self-starting reluctance motor, another with a wound rotor forming a self-starting induction motor, and the third a true synchronous motor with separately excited DC supply to rotor winding. One of the patents Tesla filed in 1887, however, also described a shorted-winding-rotor induction motor. George Westinghouse, who had already acquired rights from Ferraris (US$1,000), promptly bought Tesla's patents (US$60,000 plus US$2.50 per sold hp, paid until 1897), employed Tesla to develop his motors, and assigned C.F. Scott to help Tesla; however, Tesla left for other pursuits in 1889. The constant speed AC induction motor was found not to be suitable for street cars, but Westinghouse engineers successfully adapted it to power a mining operation in Telluride, Colorado in 1891. Westinghouse achieved its first practical induction motor in 1892 and developed a line of polyphase 60 hertz induction motors in 1893, but these early Westinghouse motors were two-phase motors with wound rotors. B.G. Lamme later developed a rotating bar winding rotor.


title: Electric motor

text: Steadfast in his promotion of three-phase development, Mikhail Dolivo-Dobrovolsky invented the three-phase induction motor in 1889, of both types cage-rotor and wound rotor with a starting rheostat, and the three-limb transformer in 1890. After an agreement between AEG and Maschinenfabrik Oerlikon, Doliwo-Dobrowolski and Charles Eugene Lancelot Brown developed larger models, namely a 20-hp squirrel cage and a 100-hp wound rotor with a starting rheostat. These were the first three-phase asynchronous motors suitable for practical operation. Since 1889, similar developments of three-phase machinery were started Wenström. At the 1891 Frankfurt International Electrotechnical Exhibition, the first long distance three-phase system was successfully presented. It was rated 15 kV and extended over 175 km from the Lauffen waterfall on the Neckar river. The Lauffen power station included a 240 kW 86 V 40 Hz alternator and a step-up transformer while at the exhibition a step-down transformer fed a 100-hp three-phase induction motor that powered an artificial waterfall, representing the transfer of the original power source. The three-phase induction is now used for the vast majority of commercial applications. Mikhail Dolivo-Dobrovolsky claimed that Tesla's motor was not practical because of two-phase pulsations, which prompted him to persist in his three-phase work.


title: Electric motor

text: The General Electric Company began developing three-phase induction motors in 1891. By 1896, General Electric and Westinghouse signed a cross-licensing agreement for the bar-winding-rotor design, later called the squirrel-cage rotor. Induction motor improvements flowing from these inventions and innovations were such that a 100-horsepower induction motor currently has the same mounting dimensions as a 7.5-horsepower motor in 1897.


title: Electric motor

text: In 2022, electric motor sales were estimated to be 800 million units, increasing by 10% annually. Electric motors consume ~50% of the world's electricity.


title: Electric motor

text: The two mechanical parts of an electric motor are the rotor, which moves, and the stator, which does not. It also includes two electrical parts, a set of magnets and an armature, one of which is attached to the rotor and the other to the stator, together forming a magnetic circuit:


title: Electric motor

text: The rotor is supported by bearings, which allow the rotor to turn on its axis. The bearings are in turn supported by the motor housing.


title: Electric motor

text: The rotor is the moving part that delivers the mechanical power. The rotor typically holds conductors that carry currents, which the magnetic field of the stator exerts force on to turn the shaft. Alternatively, some rotors carry permanent magnets, and the stator holds the conductors. Permanent magnets offer high efficiency over a larger operating speed and power range.


title: Electric motor

text: An air gap between the stator and rotor allows it to turn. The width of the gap has a significant effect on the motor's electrical characteristics. It is generally made as small as possible, as a large gap weakens performance. It is the main source of the low power factor at which motors operate. The magnetizing current increases and the power factor decreases with the air gap, so narrow gaps are better. Conversely, gaps that are too small may pose mechanical problems in addition to noise and losses.


title: Electric motor

text: The motor shaft extends through the bearings to the outside of the motor, where the load is applied. Because the forces of the load are exerted beyond the outermost bearing, the load is said to be overhung.


title: Electric motor

text: The stator surrounds the rotor, and usually holds field magnets, which are either electromagnets consisting of wire windings around a ferromagnetic iron core or permanent magnets. These create a magnetic field that passes through the rotor armature, exerting force on the windings. The stator core is made up of many thin metal sheets that are insulated from each other, called laminations. These laminations are made using electrical steel which has a specified magnetic permeability, hysteresis, and saturation. Laminations are used to reduce losses that would result from induced circulating eddy currents that would flow if a solid core were used. Mains powered AC motors typically immobilize the wires within the windings by impregnating them with varnish in a vacuum. This prevents the wires in the winding from vibrating against each other which would abrade the wire insulation causing it to fail prematurely. Resin-packed motors, used in deep well submersible pumps, washing machines, and air conditioners, encapsulate the stator in plastic resin to prevent corrosion and/or reduce conducted noise.


title: Electric motor

text: The armature consists of wire windings on a ferromagnetic core. Electric current passing through the wire causes the magnetic field from the field magnet to exert a force (Lorentz force) on it, turning the rotor, which delivers the mechanical output. Windings are wires that are laid in coils, usually wrapped around a laminated, soft, iron, ferromagnetic core so as to form magnetic poles when energized with current.


title: Electric motor

text: Electric machines come in salient- and nonsalient-pole configurations. In a salient-pole motor the ferromagnetic cores on the rotor and stator have projections called poles facing each other, with a wire winding around each pole below the pole face, which become north or south poles of the magnetic field when current flows through the wire. In a nonsalient-pole (or distributed field or round-rotor) motor, the ferromagnetic core is a smooth cylinder, with the windings distributed evenly in slots about the circumference. Supplying alternating current in the windings creates poles in the core that rotate continuously. A shaded-pole motor has a winding around part of the pole that delays the phase of the magnetic field for that pole.


title: Electric motor

text: A commutator is a rotary electrical switch that supplies current to the rotor. It periodically reverses the flow of current in the rotor windings as the shaft rotates. It consists of a cylinder composed of multiple metal contact segments on the armature. Two or more electrical contacts called "brushes" made of a soft conductive material like carbon press against the commutator. The brushes make sliding contact with successive commutator segments as it rotates, supplying current to the rotor. The windings on the rotor are connected to the commutator segments. The commutator periodically reverses the current direction in the rotor windings with each half turn (180°), so the torque applied to the rotor is always in the same direction. Without this current reversal, the direction of torque on each rotor winding would reverse with each half turn, so the rotor would stop. Commutators are inefficient and commutated motors have been mostly replaced by brushless direct current motors, permanent magnet motors, and induction motors.


title: Electric motor

text: AC motors' commutation can be achieved using either a slip ring commutator or external commutation. It can be fixed-speed or variable-speed control type, and can be synchronous or asynchronous. Universal motors can run on either AC or DC.


title: Electric motor

text: DC motors can be operated at variable speeds by adjusting the voltage applied to the terminals or by using pulse-width modulation (PWM).


title: Electric motor

text: AC motors operated at a fixed speed are generally powered directly from the grid or through motor soft starters.


title: Electric motor

text: AC motors operated at variable speeds are powered with various power inverter, variable-frequency drive or electronic commutator technologies.


title: Electric motor

text: The term electronic commutator is usually associated with self-commutated brushless DC motor and switched reluctance motor applications.


title: Electric motor

text: Electric motors operate on one of three physical principles: magnetism, electrostatics and piezoelectricity.


title: Electric motor

text: In magnetic motors, magnetic fields are formed in both the rotor and the stator. The product between these two fields gives rise to a force, and thus a torque on the motor shaft. One, or both, of these fields must change with the rotation of the rotor. This is done by switching the poles on and off at the right time, or varying the strength of the pole.


title: Electric motor

text: Once started, a synchronous motor requires synchrony with the moving magnetic field's speed for all normal torque conditions.


title: Electric motor

text: In synchronous machines, the magnetic field must be provided by means other than induction, such as from separately excited windings or permanent magnets.


title: Electric motor

text: A fractional-horsepower motor either has a rating below about 1 horsepower (0.746 kW), or is manufactured with a standard-frame size smaller than a standard 1 HP motor. Many household and industrial motors are in the fractional-horsepower class.


title: Electric motor

text: Most DC motors are small permanent magnet (PM) types. They contain a brushed internal mechanical commutation to reverse motor windings' current in synchronism with rotation.


title: Electric motor

text: A commutated DC motor has a set of rotating windings wound on an armature mounted on a rotating shaft. The shaft also carries the commutator. Thus, every brushed DC motor has AC flowing through its windings. Current flows through one or more pairs of brushes that touch the commutator; the brushes connect an external source of electric power to the rotating armature.


title: Electric motor

text: The rotating armature consists of one or more wire coils wound around a laminated, magnetically "soft" ferromagnetic core. Current from the brushes flows through the commutator and one winding of the armature, making it a temporary magnet (an electromagnet). The magnetic field produced interacts with a stationary magnetic field produced by either PMs or another winding (a field coil), as part of the motor frame. The force between the two magnetic fields rotates the shaft. The commutator switches power to the coils as the rotor turns, keeping the poles from ever fully aligning with the magnetic poles of the stator field, so that the rotor keeps turning as long as power is applied.


title: Electric motor

text: Many of the limitations of the classic commutator DC motor are due to the need for brushes to maintain contact with the commutator, creating friction. The brushes create sparks while crossing the insulating gaps between commutator sections. Depending on the commutator design, the brushes may create short circuits between adjacent sections—and hence coil ends. Furthermore, the rotor coils' inductance causes the voltage across each to rise when its circuit opens, increasing the sparking. This sparking limits the maximum speed of the machine, as too-rapid sparking will overheat, erode, or even melt the commutator. The current density per unit area of the brushes, in combination with their resistivity, limits the motor's output. Crossing the gaps also generates electrical noise; sparking generates RFI. Brushes eventually wear out and require replacement, and the commutator itself is subject to wear and maintenance or replacement. The commutator assembly on a large motor is a costly element, requiring precision assembly of many parts. On small motors, the commutator is usually permanently integrated into the rotor, so replacing it usually requires replacing the rotor.


title: Electric motor

text: Large brushes create a large contact area, which maximizes motor output, while small brushes have low mass to maximize the speed at which the motor can run without excessive sparking. (Small brushes are desirable for their lower cost.) Stiffer brush springs can be used to make brushes of a given mass work at a higher speed, despite greater friction losses (lower efficiency) and accelerated brush and commutator wear. Therefore, DC motor brush design entails a trade-off between output power, speed, and efficiency/wear.


title: Electric motor

text: A permanent magnet (PM) motor does not have a field winding on the stator frame, relying instead on PMs to provide the magnetic field. Compensating windings in series with the armature may be used on large motors to improve commutation under load. This field is fixed and cannot be adjusted for speed control. PM fields (stators) are convenient in miniature motors to eliminate the power consumption of the field winding. Most larger DC motors are of the "dynamo" type, which have stator windings. Historically, PMs could not be made to retain high flux if they were disassembled; field windings were more practical to obtain the needed flux. However, large PMs are costly, as well as dangerous and difficult to assemble; this favors wound fields for large machines.


title: Electric motor

text: To minimize overall weight and size, miniature PM motors may use high energy magnets made with neodymium; most are neodymium-iron-boron alloy. With their higher flux density, electric machines with high-energy PMs are at least competitive with all optimally designed singly-fed synchronous and induction electric machines. Miniature motors resemble the structure in the illustration, except that they have at least three rotor poles (to ensure starting, regardless of rotor position) and their outer housing is a steel tube that magnetically links the exteriors of the curved field magnets.


title: Electric motor

text: Some of the problems of the brushed DC motor are eliminated in the BLDC design. In this motor, the mechanical "rotating switch" or commutator is replaced by an external electronic switch synchronised to the rotor's position. BLDC motors are typically 85%+ efficient, reaching up to 96.5%, while brushed DC motors are typically 75–80% efficient.


title: Electric motor

text: The BLDC motor's characteristic trapezoidal counter-electromotive force (CEMF) waveform is derived partly from the stator windings being evenly distributed, and partly from the placement of the rotor's permanent magnets. Also known as electronically commutated DC or inside-out DC motors, the stator windings of trapezoidal BLDC motors can be single-phase, two-phase or three-phase and use Hall effect sensors mounted on their windings for rotor position sensing and low cost closed-loop commutator control.


title: Electric motor

text: BLDC motors are commonly used where precise speed control is necessary, as in computer disk drives or video cassette recorders. The spindles within CD, CD-ROM (etc.) drives, and mechanisms within office products, such as fans, laser printers and photocopiers. They have several advantages over conventional motors:


title: Electric motor

text: Modern BLDC motors range in power from a fraction of a watt to many kilowatts. Larger BLDC motors rated up to about 100 kW are used in electric vehicles. They also find use in electric model aircraft.


title: Electric motor

text: The switched reluctance motor (SRM) has no brushes or permanent magnets, and the rotor has no electric currents. Torque comes from a slight misalignment of poles on the rotor with poles on the stator. The rotor aligns itself with the magnetic field of the stator, while the stator field windings are sequentially energized to rotate the stator field.


title: Electric motor

text: The magnetic flux created by the field windings follows the path of least magnetic sending the flux through rotor poles that are closest to the energized poles of the stator, thereby magnetizing those poles of the rotor and creating torque. As the rotor turns, different windings are energized, keeping the rotor turning.


title: Electric motor

text: A commutated, electrically excited, series or parallel wound motor is referred to as a universal motor because it can be designed to operate on either AC or DC power. A universal motor can operate well on AC because the current in both the field and the armature coils (and hence the resultant magnetic fields) synchronously reverse polarity, and hence the resulting mechanical force occurs in a constant direction of rotation.


title: Electric motor

text: Operating at normal power line frequencies, universal motors are often used in sub-kilowatt applications. Universal motors formed the basis of the traditional railway traction motor in electric railways. In this application, using AC power on a motor designed to run on DC would experience efficiency losses due to eddy current heating of their magnetic components, particularly the motor field pole-pieces that, for DC, would have used solid (un-laminated) iron. They are now rarely used.


title: Electric motor

text: An advantage is that AC power may be used on motors that specifically have high starting torque and compact design if high running speeds are used. By contrast, maintenance is higher and lifetimes are shortened. Such motors are used in devices that are not heavily used, and have high starting-torque demands. Multiple taps on the field coil provide (imprecise) stepped speed control. Household blenders that advertise many speeds typically combine a field coil with several taps and a diode that can be inserted in series with the motor (causing the motor to run on half-wave rectified AC). Universal motors also lend themselves to electronic speed control and, as such, are a choice for devices such as domestic washing machines. The motor can agitate the drum (both forwards and in reverse) by switching the field winding with respect to the armature.


title: Electric motor

text: Whereas SCIMs cannot turn a shaft faster than allowed by the power line frequency, universal motors can run at much higher speeds. This makes them useful for appliances such as blenders, vacuum cleaners, and hair dryers where high speed and light weight are desirable. They are also commonly used in portable power tools, such as drills, sanders, circular and jig saws, where the motor's characteristics work well. Many vacuum cleaner and weed trimmer motors exceed , while miniature grinders may exceed .


title: Electric motor

text: AC induction and synchronous motors are optimized for operation on single-phase or polyphase sinusoidal or quasi-sinusoidal waveform power such as supplied for fixed-speed applications by the AC power grid or for variable-speed application from variable-frequency drive (VFD) controllers.


title: Electric motor

text: An induction motor is an asynchronous AC motor where power is transferred to the rotor by electromagnetic induction, much like transformer action. An induction motor resembles a rotating transformer, because the stator (stationary part) is essentially the primary side of the transformer and the rotor (rotating part) is the secondary side. Polyphase induction motors are widely used in industry.


title: Electric motor

text: Induction motors may be divided into Squirrel Cage Induction Motors (SCIM) and Wound Rotor Induction Motors (WRIM). SCIMs have a heavy winding made up of solid bars, usually aluminum or copper, electrically connected by rings at the ends of the rotor. The bars and rings as a whole are much like an animal's rotating exercise cage.


title: Electric motor

text: Currents induced into this winding provide the rotor magnetic field. The shape of the rotor bars determines the speed-torque characteristics. At low speeds, the current induced in the squirrel cage is nearly at line frequency and tends to stay in the outer parts of the cage. As the motor accelerates, the slip frequency becomes lower, and more current reaches the interior. By shaping the bars to change the resistance of the winding portions in the interior and outer parts of the cage, a variable resistance is effectively inserted in the rotor circuit. However, most such motors employ uniform bars.


title: Electric motor

text: In a WRIM, the rotor winding is made of many turns of insulated wire and is connected to slip rings on the motor shaft. An external resistor or other control device can be connected in the rotor circuit. Resistors allow control of the motor speed, although dissipating significant power. A converter can be fed from the rotor circuit and return the slip-frequency power that would otherwise be wasted into the power system through an inverter or separate motor-generator.


title: Electric motor

text: WRIMs are used primarily to start a high inertia load or a load that requires high starting torque across the full speed range. By correctly selecting the resistors used in the secondary resistance or slip ring starter, the motor is able to produce maximum torque at a relatively low supply current from zero speed to full speed.


title: Electric motor

text: Motor speed can be changed because the motor's torque curve is effectively modified by the amount of resistance connected to the rotor circuit. Increasing resistance lowers the speed of maximum torque. If the resistance is increased beyond the point where the maximum torque occurs at zero speed, the torque is further reduced.


title: Electric motor

text: When used with a load that has a torque curve that increases with speed, the motor operates at the speed where the torque developed by the motor is equal to the load torque. Reducing the load causes the motor to speed up, while increasing the load causes the motor to slow down until the load and motor torque are again equal. Operated in this manner, the slip losses are dissipated in the secondary resistors and can be significant. The speed regulation and net efficiency is poor.


title: Electric motor

text: A torque motor can operate indefinitely while stalled, that is, with the rotor blocked from turning, without incurring damage. In this mode of operation, the motor applies a steady torque to the load.


title: Electric motor

text: A common application is the supply- and take-up reel motors in a tape drive. In this application, driven by a low voltage, the characteristics of these motors apply a steady light tension to the tape whether or not the capstan is feeding tape past the tape heads. Driven from a higher voltage (delivering a higher torque), torque motors can achieve fast-forward and rewind operation without requiring additional mechanics such as gears or clutches. In the computer gaming world, torque motors are used in force feedback steering wheels.


title: Electric motor

text: Another common application is to control the throttle of an internal combustion engine with an electronic governor. The motor works against a return spring to move the throttle in accord with the governor output. The latter monitors engine speed by counting electrical pulses from the ignition system or from a magnetic pickup and depending on the speed, makes small adjustments to the amount of current. If the engine slows down relative to the desired speed, the current increases, producing more torque, pulling against the return spring and opening the throttle. Should the engine run too fast, the governor reduces the current, allowing the return spring to pull back and reduce the throttle.


title: Electric motor

text: A synchronous electric motor is an AC motor. It includes a rotor spinning with coils passing magnets at the same frequency as the AC and produces a magnetic field to drive it. It has zero slip under typical operating conditions. By contrast induction motors must slip to produce torque. One type of synchronous motor is like an induction motor except that the rotor is excited by a DC field. Slip rings and brushes conduct current to the rotor. The rotor poles connect to each other and move at the same speed. Another type, for low load torque, has flats ground onto a conventional squirrel-cage rotor to create discrete poles. Yet another, as made by Hammond for its pre-World War II clocks, and in older Hammond organs, has no rotor windings and discrete poles. It is not self-starting. The clock requires manual starting by a small knob on the back, while the older Hammond organs had an auxiliary starting motor connected by a spring-loaded manually operated switch.


title: Electric motor

text: Hysteresis synchronous motors typically are (essentially) two-phase motors with a phase-shifting capacitor for one phase. They start like induction motors, but when slip rate decreases sufficiently, the rotor (a smooth cylinder) becomes temporarily magnetized. Its distributed poles make it act like a permanent magnet synchronous motor. The rotor material, like that of a common nail, stays magnetized, but can be demagnetized with little difficulty. Once running, the rotor poles stay in place; they do not drift.


title: Electric motor

text: Low-power synchronous timing motors (such as those for traditional electric clocks) may have multi-pole permanent magnet external cup rotors, and use shading coils to provide starting torque. "Telechron" clock motors have shaded poles for starting torque, and a two-spoke ring rotor that performs like a discrete two-pole rotor.


title: Electric motor

text: Doubly fed electric motors have two independent multiphase winding sets, which contribute active (i.e., working) power to the energy conversion process, with at least one of the winding sets electronically controlled for variable speed operation. Two independent multiphase winding sets (i.e., dual armature) are the maximum provided in a single package without topology duplication. Doubly-fed electric motors have an effective constant torque speed range that is twice synchronous speed for a given frequency of excitation. This is twice the constant torque speed range as singly-fed electric machines, which have only one active winding set.


title: Electric motor

text: A doubly-fed motor allows for a smaller electronic converter but the cost of the rotor winding and slip rings may offset the saving in the power electronics components. Difficulties affect controlling speed near synchronous speed limit applications.


title: Electric motor

text: The coreless or ironless DC motor is a specialized permanent magnet DC motor. Optimized for rapid acceleration, the rotor is constructed without an iron core. The rotor can take the form of a winding-filled cylinder, or a self-supporting structure comprising only wire and bonding material. The rotor can fit inside the stator magnets; a magnetically soft stationary cylinder inside the rotor provides a return path for the stator magnetic flux. A second arrangement has the rotor winding basket surrounding the stator magnets. In that design, the rotor fits inside a magnetically soft cylinder that can serve as the motor housing, and provides a return path for the flux.


title: Electric motor

text: Because the rotor is much lower mass than a conventional rotor, it can accelerate much more rapidly, often achieving a mechanical time constant under one millisecond. This is especially true if the windings use aluminum rather than (heavier) copper. The rotor has no metal mass to act as a heat sink; even small motors must be cooled. Overheating can be an issue for these designs.


title: Electric motor

text: The vibrating alert of cellular phones can be generated by cylindrical permanent-magnet motors, or disc-shaped types that have a thin multipolar disc field magnet, and an intentionally unbalanced molded-plastic rotor structure with two bonded coreless coils. Metal brushes and a flat commutator switch power to the rotor coils.


title: Electric motor

text: Related limited-travel actuators have no core and a bonded coil placed between the poles of high-flux thin permanent magnets. These are the fast head positioners for rigid-disk ("hard disk") drives. Although the contemporary design differs considerably from that of loudspeakers, it is still loosely (and incorrectly) referred to as a "voice coil" structure, because some earlier rigid-disk-drive heads moved in straight lines, and had a drive structure much like that of a loudspeaker.


title: Electric motor

text: The printed armature or pancake motor has windings shaped as a disc running between arrays of high-flux magnets. The magnets are arranged in a circle facing the rotor spaced to form an axial air gap. This design is commonly known as the pancake motor because of its flat profile.


title: Electric motor

text: The armature (originally formed on a printed circuit board) is made from punched copper sheets that are laminated together using advanced composites to form a thin, rigid disc. The armature does not have a separate ring commutator. The brushes move directly on the armature surface making the whole design compact.


title: Electric motor

text: An alternative design is to use wound copper wire laid flat with a central conventional commutator, in a flower and petal shape. The windings are typically stabilized with electrical epoxy potting systems. These are filled epoxies that have moderate, mixed viscosity and a long gel time. They are highlighted by low shrinkage and low exotherm, and are typically UL 1446 recognized as a potting compound insulated with , Class H rating.


title: Electric motor

text: The unique advantage of ironless DC motors is the absence of cogging (torque variations caused by changing attraction between the iron and the magnets). Parasitic eddy currents cannot form in the rotor as it is totally ironless, although iron rotors are laminated. This can greatly improve efficiency, but variable-speed controllers must use a higher switching rate (>40 kHz) or DC because of decreased electromagnetic induction.


title: Electric motor

text: These motors were invented to drive the capstan(s) of magnetic tape drives, where minimal time to reach operating speed and minimal stopping distance were critical. Pancake motors are widely used in high-performance servo-controlled systems, robotic systems, industrial automation and medical devices. Due to the variety of constructions now available, the technology is used in applications from high temperature military to low cost pump and basic servos.


title: Electric motor

text: Another approach (Magnax) is to use a single stator sandwiched between two rotors. One such design has produced peak power of 15 kW/kg, sustained power around 7.5 kW/kg. This yokeless axial flux motor offers a shorter flux path, keeping the magnets further from the axis. The design allows zero winding overhang; 100 percent of the windings are active. This is enhanced with the use of rectangular-crosssection copper wire. The motors can be stacked to work in parallel. Instabilities are minimized by ensuring that the two rotor discs put equal and opposing forces onto the stator disc. The rotors are connected directly to one another via a shaft ring, cancelling out the magnetic forces.


title: Electric motor

text: A servo motor is a motor that is used within a position-control or speed-control feedback system. Servomotors are used in applications such as machine tools, pen plotters, and other process systems. Motors intended for use in a servomechanism must have predictable characteristics for speed, torque, and power. The speed/torque curve is important and is high ratio for a servo motor. Dynamic response characteristics such as winding inductance and rotor inertia are important; these factors limit performance. Large, powerful, but slow-responding servo loops may use conventional AC or DC motors and drive systems with position or speed feedback. As dynamic response requirements increase, more specialized motor designs such as coreless motors are used. AC motors' superior power density and acceleration characteristics tends to favor permanent magnet synchronous, BLDC, induction, and SRM drive approaches.


title: Electric motor

text: A servo system differs from some stepper motor applications in that position feedback is continuous while the motor is running. A stepper system inherently operates open-loop—relying on the motor not to "miss steps" for short term accuracy—with any feedback such as a "home" switch or position encoder external to the motor system.


title: Electric motor

text: Stepper motors are typically used to provide precise rotations. An internal rotor containing permanent magnets or a magnetically soft rotor with salient poles is controlled by a set of electronically switched external magnets. A stepper motor may also be thought of as a cross between a DC electric motor and a rotary solenoid. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a synchronous motor, the stepper motor may not rotate continuously; instead, it moves in steps—starting and then stopping—advancing from one position to the next as field windings are energized and de-energized in sequence. Depending on the sequence, the rotor may turn forwards or backwards, and it may change direction, stop, speed up or slow down at any time.


title: Electric motor

text: Simple stepper motor drivers entirely energize or entirely de-energize the field windings, leading the rotor to "cog" to a limited number of positions. Microstepping drivers can proportionally control the power to the field windings, allowing the rotors to position between cog points and rotate smoothly. Computer-controlled stepper motors are one of the most versatile positioning systems, particularly as part of a digital servo-controlled system.


title: Electric motor

text: Stepper motors can be rotated to a specific angle in discrete steps with ease, and hence stepper motors are used for read/write head positioning in early disk drives, where the precision and speed they offered could correctly position the read/write head. As drive density increased, precision and speed limitations made them obsolete for hard drives—the precision limitation made them unusable, and the speed limitation made them uncompetitive—thus newer hard disk drives use voice coil-based head actuator systems. (The term "voice coil" in this connection is historic; it refers to the structure in a cone-type loudspeaker.)


title: Electric motor

text: Stepper motors are often used in computer printers, optical scanners, and digital photocopiers to move the active element, the print head carriage (inkjet printers), and the platen or feed rollers.


title: Electric motor

text: So-called quartz analog wristwatches contain the smallest commonplace stepping motors; they have one coil, draw little power, and have a permanent magnet rotor. The same kind of motor drives battery-powered quartz clocks. Some of these watches, such as chronographs, contain more than one stepper motor.


title: Electric motor

text: Closely related in design to three-phase AC synchronous motors, stepper motors and SRMs are classified as variable reluctance motor type.


title: Electric motor

text: A linear motor is essentially any electric motor that has been "unrolled" so that, instead of producing torque (rotation), it produces a straight-line force along its length.


title: Electric motor

text: Linear motors are most commonly induction motors or stepper motors. Linear motors are commonly found in roller-coasters where the rapid motion of the motorless railcar is controlled by the rail. They are also used in maglev trains, where the train "flies" over the ground. On a smaller scale, the 1978 era HP 7225A pen plotter used two linear stepper motors to move the pen along the X and Y axes.


title: Electric motor

text: An electric motor converts electrical energy to mechanical energy through the force between two opposed magnetic fields. At least one of the two magnetic fields must be created by an electromagnet through the magnetic field caused by an electrical current.


title: Electric motor

text: The force between a current formula_1 in a conductor of length formula_2 perpendicular to a magnetic field formula_3 may be calculated using the Lorentz force law:


title: Electric motor

text: Where formula_5 is shaft speed in rpm and T is torque, a motor's mechanical power output P is given by,


title: Electric motor

text: in SI units with shaft angular speed, formula_7, expressed in radians per second, and T expressed in newton-meters,


title: Electric motor

text: In an asynchronous or induction motor, the relationship between motor speed and air gap power is given by the following:


title: Electric motor

text: The movement of armature windings of a direct-current or universal motor through a magnetic field, induce a voltage in them. This voltage tends to oppose the motor supply voltage and so is called "back electromotive force (EMF)". The voltage is proportional to the running speed of the motor. The back EMF of the motor, plus the voltage drop across the winding internal resistance and brushes, must equal the voltage at the brushes. This provides the fundamental mechanism of speed regulation in a DC motor. If the mechanical load increases, the motor slows down; a lower back EMF results, and more current is drawn from the supply. This increased current provides the additional torque to balance the load.


title: Electric motor

text: In AC machines, it is sometimes useful to consider a back EMF source within the machine; this is of particular concern for close speed regulation of induction motors on VFDs.


title: Electric motor

text: Motor losses are mainly due to resistive losses in windings, core losses and mechanical losses in bearings, and aerodynamic losses, particularly where cooling fans are present, also occur.


title: Electric motor

text: Losses also occur in commutation, mechanical commutators spark; electronic commutators and also dissipate heat.


title: Electric motor

text: To calculate a motor's efficiency, the mechanical output power is divided by the electrical input power:


title: Electric motor

text: where formula_12 is energy conversion efficiency, formula_13 is electrical input power, and formula_14 is mechanical output power:


title: Electric motor

text: where formula_17 is input voltage, formula_1 is input current, formula_19 is output torque, and formula_20 is output angular velocity. It is possible to derive analytically the point of maximum efficiency. It is typically at less than 1/2 the stall torque.


title: Electric motor

text: Various national regulatory authorities have enacted legislation to encourage the manufacture and use of higher-efficiency motors. Electric motors have efficiencies ranging from at least 15% for shaded pole motors, up to 98% for permanent magnet motors, with efficiency also dependent on load. Peak efficiency is usually at 75% of the rated load. So (as an example) a 10 HP motor is most efficient when driving a load that requires 7.5 HP. Efficiency also depends on motor size; larger motors tend to be more efficient. Some motors can not operate continually for more than a specified period of time (e.g. for more than an hour per run)


title: Electric motor

text: From this, he showed that the most efficient motors are likely to have relatively large magnetic poles. However, the equation only directly relates to non PM motors.


title: Electric motor

text: Electromagnetic motors derive torque from the vector product of the interacting fields. Calculating torque requires knowledge of the fields in the air gap. Once these have been established, the torque is the integral of all the force vectors multiplied by the vector's radius. The current flowing in the winding produces the fields. For a motor using a magnetic material the field is not proportional to the current.


title: Electric motor

text: A figure relating the current to the torque can inform motor selection. The maximum torque for a motor depends on the maximum current, absent thermal considerations.


title: Electric motor

text: When optimally designed within a given core saturation constraint and for a given active current (i.e., torque current), voltage, pole-pair number, excitation frequency (i.e., synchronous speed), and air-gap flux density, all categories of electric motors/generators exhibit virtually the same maximum continuous shaft torque (i.e., operating torque) within a given air-gap area with winding slots and back-iron depth, which determines the physical size of electromagnetic core. Some applications require bursts of torque beyond the maximum, such as bursts to accelerate an electric vehicle from standstill. Always limited by magnetic core saturation or safe operating temperature rise and voltage, the capacity for torque bursts beyond the maximum differs significantly across motor/generator types.


title: Electric motor

text: Electric machines without a transformer circuit topology, such as that of WRSMs or PMSMs, cannot provide torque bursts without saturating the magnetic core. At that point, additional current cannot increase torque. Furthermore, the permanent magnet assembly of PMSMs can be irreparably damaged.


title: Electric motor

text: Electric machines with a transformer circuit topology, such as induction machines, induction doubly-fed electric machines, and induction or synchronous wound-rotor doubly-fed (WRDF) machines, permit torque bursts because the EMF-induced active current on either side of the transformer oppose each other and thus contribute nothing to the transformer coupled magnetic core flux density, avoiding core saturation.


title: Electric motor

text: Electric machines that rely on induction or asynchronous principles short-circuit one port of the transformer circuit and as a result, the reactive impedance of the transformer circuit becomes dominant as slip increases, which limits the magnitude of active (i.e., real) current. Torque bursts two to three times higher than the maximum design torque are realizable.


title: Electric motor

text: The brushless wound-rotor synchronous doubly-fed (BWRSDF) machine is the only electric machine with a truly dual ported transformer circuit topology (i.e., both ports independently excited with no short-circuited port). The dual ported transformer circuit topology is known to be unstable and requires a multiphase slip-ring-brush assembly to propagate limited power to the rotor winding set. If a precision means were available to instantaneously control torque angle and slip for synchronous operation during operation while simultaneously providing brushless power to the rotor winding set, the active current of the BWRSDF machine would be independent of the reactive impedance of the transformer circuit and bursts of torque significantly higher than the maximum operating torque and far beyond the practical capability of any other type of electric machine would be realizable. Torque bursts greater than eight times operating torque have been calculated.


title: Electric motor

text: The continuous torque density of conventional electric machines is determined by the size of the air-gap area and the back-iron depth, which are determined by the power rating of the armature winding set, the speed of the machine, and the achievable air-gap flux density before core saturation. Despite the high coercivity of neodymium or samarium-cobalt permanent magnets, continuous torque density is virtually the same amongst electric machines with optimally designed armature winding sets. Continuous torque density relates to method of cooling and permissible operation period before destruction by overheating of windings or permanent magnet damage.


title: Electric motor

text: Other sources state that various e-machine topologies have differing torque density. One source shows the following:


title: Electric motor

text: where—specific torque density is normalized to 1.0 for the surface permanent magnet (SPM)—brushless ac, 180° current conduction.


title: Electric motor

text: Torque density is approximately four times greater for liquid cooled motors, compared to those which are air cooled.


title: Electric motor

text: Another source notes that PMSM up to 1 MW have considerably higher torque density than induction machines.


title: Electric motor

text: The continuous power density is determined by the product of the continuous torque density and the constant torque speed range. Electric motors can achieve densities of up to 20KW/KG, meaning 20 Kilowatts of output power per kilogram.


title: Electric motor

text: The latter source, which can be responsible for the "whining noise" of electric motors, is called electromagnetically induced acoustic noise.


title: Electric motor

text: An electrostatic motor is based on the attraction and repulsion of electric charge. Usually, electrostatic motors are the dual of conventional coil-based motors. They typically require a high-voltage power supply, although small motors employ lower voltages. Conventional electric motors instead employ magnetic attraction and repulsion, and require high current at low voltages. In the 1750s, the first electrostatic motors were developed by Benjamin Franklin and Andrew Gordon. Electrostatic motors find frequent use in micro-electro-mechanical systems (MEMS) where their drive voltages are below 100 volts, and where moving, charged plates are far easier to fabricate than coils and iron cores. The molecular machinery that runs living cells is often based on linear and rotary electrostatic motors.


title: Electric motor

text: A piezoelectric motor or piezo motor is a type of electric motor based upon the change in shape of a piezoelectric material when an electric field is applied. Piezoelectric motors make use of the converse piezoelectric effect whereby the material produces acoustic or ultrasonic vibrations to produce linear or rotary motion. In one mechanism, the elongation in a single plane is used to make a series of stretches and position holds, similar to the way a caterpillar moves.


title: Electric motor

text: An electrically powered spacecraft propulsion system uses electric motor technology to propel spacecraft in outer space. Most systems are based on electrically accelerating propellant to high speed, while some systems are based on electrodynamic tethers principles of propulsion to the magnetosphere.


title: Luke Bryan

text: Thomas Luther "Luke" Bryan (born July 17, 1976) is an American country singer, songwriter, and television personality. He began his music career writing songs for Travis Tritt and Billy Currington before signing with Capitol Nashville in 2007. He is one of the most successful and awarded country artists of the 2010s and 2020s.


title: Luke Bryan

text: Bryan's first ten albums – "I'll Stay Me" (2007), "Doin' My Thing" (2009), "Tailgates & Tanlines" (2011), "Crash My Party" (2013), "Spring Break...Here to Party" (2013), "Spring Break...Checkin' Out" (2015), "Kill the Lights" (2015), "Farm Tour... Here's to the Farmer" (2016), "What Makes You Country" (2017), and "Born Here Live Here Die Here" (2020) – have included 27 number-one hits. Bryan often co-writes with Jeff Stevens. Since 2018, Bryan has been a judge on "American Idol".


title: Luke Bryan

text: Bryan is a five-time "Entertainer of the Year", being awarded by both the Academy of Country Music Awards and the Country Music Association. In 2019, Bryan's 2013 album "Crash My Party" received the first Album of the Decade award from the Academy of Country Music. He is one of the world's best-selling music artists, with over 75 million records sold.


title: Luke Bryan

text: Instead, Luke went to college at Georgia Southern University in Statesboro, Georgia, where he joined the Sigma Chi fraternity and graduated in 1999 with a bachelor's degree in business administration. Luke Bryan met his future wife Caroline singing in a bar in Georgia. They went on dating for a year and a half before she ended things with Luke. Luke and Caroline went their separate ways of Luke moving to Nashville to focus on music and Caroline went on to focus on herself. After a few years, Luke came back and was performing in a bar where they reconnected with each other.


title: Luke Bryan

text: Two years later, Bryan finally made it to Nashville, after his father told him to pack his truck to pursue a career in music. He initially gained success as a songwriter, but soon after signed as a performer; his first major success was "All My Friends Say".


title: Luke Bryan

text: Soon after his arrival in Nashville, Bryan joined a publishing house in the city. Among his first cuts was the title track of Travis Tritt's 2004 album "My Honky Tonk History".


title: Luke Bryan

text: He was later signed by Capitol Nashville to a recording contract. In the meantime, Bryan co-wrote Billy Currington's single "Good Directions", which went to number one on the Hot Country Songs chart in mid-2007. Bryan co-wrote his debut single, "All My Friends Say", with producer Jeff Stevens. This song reached a peak of number 5 on the Hot Country Songs chart. In August 2007, Capitol Nashville released Bryan's debut album, "I'll Stay Me". Bryan wrote or co-wrote all but one of its 11 songs. The album's second single, "We Rode in Trucks", peaked at number 33 while "Country Man" reached number 10.


title: Luke Bryan

text: On March 10, 2009, he released an EP titled "Spring Break with All My Friends" that featured two new songs, "Sorority Girls" and "Take My Drunk Ass Home," plus an acoustic version of "All My Friends Say". After this EP, he released his fourth single, "Do I" in May 2009. Bryan wrote the song with Charles Kelley and Dave Haywood of Lady A, whose lead singer Hillary Scott also sings backing vocals on it. The song reached number 2 on the Hot Country Songs chart.


title: Luke Bryan

text: "Do I" was included on Bryan's second album, "Doin' My Thing", which was released in October 2009. Also included on the album was a cover of OneRepublic's "Apologize". Bryan wrote the album's next two singles, "Rain Is a Good Thing" and "Someone Else Calling You Baby", with Dallas Davidson and Jeff Stevens, respectively. Both of these songs went to number one on the country music charts. AllMusic gave this album a positive review as well, with Stephen Thomas Erlewine considering Bryan more "relaxed" in comparison to his debut. On February 26, 2010, Bryan released a second EP, titled "Spring Break 2...Hangover Edition", which featured three new songs: "Wild Weekend", "Cold Beer Drinker", and "I'm Hungover". While Bryan is mainly known as a country music singer, he has explored other genres like alternative rock with his cover of "Apologize".


title: Luke Bryan

text: Bryan appeared on the April 18, 2010, episode of "Celebrity Apprentice" alongside fellow country star Emily West. The task for each team was to make over an up-and-coming country star, with Bryan being selected by Team Rocksolid, led by Bill Goldberg, and West being selected by team Tenacity, led by Cyndi Lauper. Bryan's makeover failed to impress the judges, leading to Rocksolid losing the task. Bryan's single "Rain Is a Good Thing" and West's single "Blue Sky" were both sold on iTunes, with a month's worth of sales being donated to Lauper's charity, the Stonewall Community Foundation, resulting in $25,000 being raised.


title: Luke Bryan

text: Bryan released his third EP, "Spring Break 3...It's a Shore Thing", on February 25, 2011, featuring four new songs - "In Love With the Girl," "If You Ain't Here to Party," "Shore Thing," and "Love In a College Town". This release was followed by Bryan's seventh single, "Country Girl (Shake It for Me)", which was released on March 14, 2011. Also co-written by Bryan and Davidson, it served as the lead-off single to his third studio album, "Tailgates & Tanlines", which was released August 9, 2011. The album peaked at number one on the Top Country Albums chart and number two on the "Billboard" 200 chart. "Country Girl" peaked at number 4 on the country music charts and number 22 on the "Billboard" Hot 100 chart. The album's next three singles - "I Don't Want This Night to End", "Drunk on You", and "Kiss Tomorrow Goodbye" - all reached number one on the country music charts. Bryan, along with Eric Church, sang guest vocals on Jason Aldean's "The Only Way I Know," the second single from his 2012 album, "Night Train".


title: Luke Bryan

text: On March 6, 2012, Bryan released his fourth "Spring Break" EP entitled "Spring Break 4...Suntan City". Along with the title track, which Bryan co-wrote with Dallas Davidson, Rhett Akins and Ben Hayslip, the EP includes "Spring Break-Up," "Little Bit Later On," and "Shake the Sand". On January 30, 2013, Bryan announced his first compilation album, "Spring Break...Here to Party", which includes fourteen songs - twelve from his previous "Spring Break" EPs and two new tracks. It was released on March 5. The album debuted at number one on both the "Billboard" Top Country Albums chart and the "Billboard" 200 chart, becoming the first album of his career to top the all-genre album chart. One of the new "Spring Break" songs, "Buzzkill", reached the top 20 on the Hot Country Songs chart.


title: Luke Bryan

text: Luke Bryan's fourth studio album, "Crash My Party", was released on August 12, 2013. The album's first single, "Crash My Party", was premiered in a performance at the 2013 ACM Awards and released on April 7, 2013. It reached number one on the Country Airplay chart in July 2013. The album's second single, "That's My Kind of Night", was released to country radio on August 5, 2013. It reached number one on the Hot Country Songs chart in August 2013 and peaked at number 2 on the Country Airplay chart in October 2013. The album's third single, "Drink a Beer", was released to country radio on October 24, 2013. It reached number one on the Hot Country Songs chart in January 2014 and number one on the Country Airplay chart in February 2014. During the kickoff show for his 2014 That's My Kind of Night Tour in Columbus, Ohio, Bryan announced to the crowd that "Play It Again" would become the album's fourth single. This song reached number one on both the Hot Country Songs and Country Airplay charts in May 2014. At the same time, Bryan sang guest vocals on Florida Georgia Line's 2014 single "This Is How We Roll". On July 14, 2014, the song "Roller Coaster" was released as the album's fifth single. It reached number one on the Country Airplay chart in October 2014. The album's sixth single, "I See You", was released to country radio on November 3, 2014. It reached number one on the Hot Country Songs and Country Airplay charts in February 2015.


title: Luke Bryan

text: On March 11, 2014, Bryan began his sixth year of spring performances at Spinnaker Beach Club in Panama City Beach, Florida. On the same day, he also released his sixth "Spring Break" EP, "Spring Break 6...Like We Ain't Ever".


title: Luke Bryan

text: Bryan is the only country music artist to release an album of six number one singles on both the "Billboard's" Hot Country Songs and Country Airplay charts.


title: Luke Bryan

text: On November 11, 2014, it was confirmed that Bryan had begun writing and recording songs for his upcoming fifth studio album. His last "Spring Break" album, "Spring Break...Checkin' Out", was released on March 10, 2015. It includes the six songs from the previous year's EP and five original new songs.


title: Luke Bryan

text: On May 19, 2015, Bryan released his first single from his fifth studio album, "Kill the Lights", "Kick the Dust Up", which peaked at number one on the Country Airplay chart. He co-wrote over half of the songs on this album. This album provides not only his country flare, but also has tracks that include a disco type beat along with the songs of romance. The album's second single, "Strip It Down", was released to country radio on August 4, 2015. The album was released on August 7. "Kill the Lights" sold 345,000 total copies its first week and beat out Dr. Dre's "Compton" to debut at number one on the "Billboard" 200 chart. "Strip It Down" went number one in October 2015, making fourteen cumulative number ones. The album's third single, "Home Alone Tonight", released to country radio on November 23, 2015. The song also became his fifteenth song to reach number one. The album's fourth single, "Huntin', Fishin' and Lovin' Every Day", released to country radio on March 14, 2016. All six of the singles released from Bryan's "Kill the Lights" album reached number one on the "Billboard" Country Airplay chart, making Bryan the first artist in the 27-year history of the chart to achieve six number one singles from one album.


title: Luke Bryan

text: It was announced that Bryan would perform at halftime of the 2015 Thanksgiving match-up between the Dallas Cowboys and Carolina Panthers.


title: Luke Bryan

text: In 2016, Bryan was selected as one of 30 artists to perform on "Forever Country", a mash-up track of "Take Me Home, Country Roads", "On the Road Again" and "I Will Always Love You" which celebrates 50 years of the CMA Awards.


title: Luke Bryan

text: On February 5, 2017, Bryan performed the National Anthem at Super Bowl LI at NRG Stadium in Houston, TX. In September 2017, Bryan was announced as a judge for the revival of "American Idol" on ABC.


title: Luke Bryan

text: Bryan released "Light It Up" in mid-2017. It served as the lead-off single to his sixth album, "What Makes You Country", which was released on December 8, 2017. "Most People Are Good" and "Sunrise, Sunburn, Sunset" were released as the album's second and third singles, respectively. The album's fourth single, the album's title track, released to country radio on October 22, 2018.


title: Luke Bryan

text: When "American Idol" returned for another season on ABC, Bryan returned along with Katy Perry and Lionel Richie as judges.


title: Luke Bryan

text: "Knockin' Boots" was released to country radio in March 2019. In October 2019, "What She Wants Tonight" was released to country radio as the second single from his upcoming album. In January 2020, Bryan announced his next album would be titled "Born Here Live Here Die Here" and was scheduled to be released on April 24, 2020. The announcement of the album followed the announcement of his upcoming "Proud to Be Right Here Tour". On March 13, 2020, "One Margarita" was released as the third single from his upcoming album. Due to the COVID-19 pandemic, Bryan delayed the release of the album to August 7, 2020, and rescheduled the "Proud to Be Right Here Tour" to 2021. On June 12, 2020, Bryan released the track "Build Me A Daddy" along with a music video for the song. On October 19, 2020, the song "Down to One" was made the fourth single from the album. A Deluxe edition of "Born Here Live Here Die Here", released on April 9, 2021, produced the album's fifth single, "Waves", as well as its sixth single, "Up," which was released on October 11, 2021. In October, it was announced that Bryan would host the 55th Annual Country Music Association Awards for the first time, making him the first solo host in 18 years.


title: Luke Bryan

text: Luke hosted the 50th annual ACM awards in 2015 with famous country singer Blake Shelton. Luke Bryan sung "I See You" and won entertainer of the year. Bryan was so thankful for his family also for his fans and wouldn't have been where he was without them.


title: Luke Bryan

text: Luke hosted the 55th annual CMA awards in 2021. The awards show was held in Nashville Tennessee. Luke Bryan won entertainer of the year. Since it was the 55th annual, special celebrates came to watch the show. Bryan had the privilege to honor so many of his friends and knew it was something he couldn't pass up.


title: Luke Bryan

text: Bryan is going to be hosting the 56th annual CMA awards with retired NFL quarterback Payton Manning in Nashville Tennessee in November 2022. Both Luke and Peyton are exciting to host together, Luke even said "Hey Peyton, I hope you're ready for the night of your life!"


title: Luke Bryan

text: Bryan is married to Caroline Boyer. They married on December 8, 2006, and have two sons together. They live in Williamson County, near Nashville. They named the house "Red Dirt Farm" after Luke's older sister Kelly passed away. His house is based off of the Blackberry farm in Knoxville.


title: Luke Bryan

text: In 2007, Bryan's older sister Kelly died unexpectedly at home of unknown causes. After Kelly's husband Ben Lee Cheshire died in 2014, Bryan and his wife began raising their nephew and taking care of their nieces.


title: Luke Bryan

text: The combined losses of his brother and sister inspired the performance of Bryan's single "Drink a Beer" (written by Chris Stapleton).


title: Luke Bryan

text: Bryan has supported numerous charities and causes, including the City of Hope and Red Cross. Past causes Bryan supported were AIDS and HIV, cancer, children's disaster relief, health, and human rights.


title: Luke Bryan

text: Following the death of her niece, Bryan's wife Caroline established Brett's Barn in her honor. Brett's Barn, located on their family farm, is a sanctuary for rescue animals that invites sick children to spend time with the over 20 animals they host on the farm. She and Bryan are also on the board of directors of the Brett Boyer Foundation, which raises awareness for Down Syndrome and congenital heart disease. The organization also hosts a number of fundraisers to raise money for research, including "Bike for Brett" which occurs annually on World Down Syndrome Day.


title: Luke Bryan

text: Crash My Playa is a 4-night all-inclusive concert vacation hosted by Luke Bryan in Cancun, Mexico. Past performers include Blake Shelton, Jason Aldean, Florida Georgia Line, Dierks Bentley, Chris Stapleton, Little Big Town, Sam Hunt, Dustin Lynch, Luke Combs, and Thomas Rhett.


title: Luke Bryan

text: Luke's 32 Bridge Food + Drink is located in the heart of Broadway Street in Nashville, Tennessee. The 30,000 square feet multi-level entertainment facility features 6 levels, 8 bars, 3 stages with live music and two restaurants.


title: Luke Bryan

text: Luke Bryan started his own record label, 32 Bridge Entertainment, under the Universal Music Group Nashville umbrella. In 2018, Jon Langston became the first artist signed to the new label.


title: Luke Bryan

text: Bryan possesses a high baritone vocal range of two octaves from A2 to A4. Commenting on his vocal performance in "Tailgates and Tanlines," "Slant" magazine's Jonathan Keefer described Bryan's voice as "a pleasant, if slightly nasal, baritone".


title: Luke Bryan

text: Bryan has cited country artists George Strait, Alan Jackson, Alabama, and Merle Haggard as influences on his career. He also cited hip hop bands Beastie Boys and Run-D.M.C. as a source of inspiration in an interview with "The Huffington Post", noting, "I think there's been somewhat of a change with our generation. You know, nobody grew up more countrier than me, but I mean, I had Beastie Boys playing on little boom boxes and Run D.M.C. and all forms of music, so through the years, I just think it's all constantly blending together."


title: Jalen Hurts

text: Jalen Alexander Hurts (born August 7, 1998) is an American football quarterback for the Philadelphia Eagles of the National Football League (NFL). He played his first three seasons of college football at Alabama, where he was part of the team that won the 2018 College Football Playoff National Championship, and used his final year of eligibility at Oklahoma. Selected by the Eagles in the second round of the 2020 NFL Draft, Hurts became their starter near the end of his rookie season.


title: Jalen Hurts

text: Hurts attended Channelview High School in Channelview, Texas. Hurts's father, Averion, was the football coach at Channelview High School throughout his son's high school career. As a senior, he passed for 2,384 yards with 26 touchdown passes and rushed for 1,391 yards and 25 touchdowns. Hurts was a second-team all-district selection as a sophomore and was named the District 21-6A Overall MVP as a junior during his high school playing years. He played against the Texas A&M freshman standout running back Trayveon Williams throughout his high school career. Hurts was rated as a four-star recruit and was ranked among the top dual-threat quarterbacks in the Class of 2016. Although Texas A&M made a strong push to recruit Hurts, they ultimately failed in their efforts after Hurts committed to the University of Alabama on June 5, 2015. He was recruited by Alabama's defensive line coach Bo Davis and offensive coordinator Lane Kiffin.


title: Jalen Hurts

text: In addition to football, Hurts participated in powerlifting. As a sophomore in high school, Hurts was squatting 500 pounds of weight and would eventually become regional finalist in the 198-pound weight class.


title: Jalen Hurts

text: As a true freshman for the Alabama Crimson Tide football team in 2016, Hurts competed to open the season as the starting quarterback. Blake Barnett started the first game against the USC Trojans, but by the second game, Hurts had taken over the starting role, becoming the first true freshman to start at quarterback for Alabama in 32 years (Vince Sutton in 1984 was the last). Hurts produced a historic freshman season under head coach Nick Saban. He threw for 2,780 yards and 23 touchdowns with nine interceptions. His completion percentage was at 62.8 percent, and he finished the season with a quarterback rating of 139.12. He rushed for a total of 954 yards and 13 touchdowns, breaking the school single-season record for rushing yards by a quarterback, surpassing Steadman Shealy's previous record of 791 yards. He finished the 2016 season with 36 overall touchdowns breaking the previous record for touchdowns in a single season for the Crimson Tide (35) set by Blake Sims in 2014. Hurts became the first quarterback coached by Nick Saban to rush for more than 11 touchdowns in a single season. He was the first player in Alabama history to pass for 300 yards and rush for 100 yards in the same game and the first quarterback to rush for 120 yards or more in multiple games. In the Iron Bowl game against Auburn, Hurts completed 75% of his passes, which set a new Iron Bowl record. Alabama concluded its 2016–2017 regular season with a perfect 12–0 (8–0 SEC) record. On November 30, 2016, Hurts was declared one of the ten finalists for the Manning Award, which is given to the nation's top college quarterback. On December 3, 2016, he led his team to win the 2016 SEC Championship over the Florida Gators and was subsequently named SEC Offensive Player of the Year, SEC Freshman of the Year, and received Freshman All-American from several publications. Hurts was featured on the cover page of "Sports Illustrated" College Football Playoff magazine on December 6, 2016. On January 9, 2017, top-seeded Alabama lost the 2017 College Football Playoff National Championship against the Clemson Tigers by a score of 35–31. The bowl game was played at Raymond James Stadium in Tampa.


title: Jalen Hurts

text: In 2017, Hurts led the Tide to a 13–1 season, giving them a playoff spot as a #4 seed, where they played Clemson in the 2018 Sugar Bowl. Hurts was the offensive MVP in that game, with Daron Payne being the defensive MVP in a 24–6 win over the Tigers. Hurts was benched at halftime of the 2018 College Football Playoff National Championship for true freshman Tua Tagovailoa. Hurts won his first National Championship as the Crimson Tide defeated the Georgia Bulldogs by a score of 26–23 in overtime. Overall, he finished the 2017 season with 2,081 passing yards, 17 passing touchdowns, and one interception to go along with 855 rushing yards and eight rushing touchdowns.


title: Jalen Hurts

text: After Tagovailoa helped lead the Crimson Tide to a comeback victory in the National Championship the year before, questions arose if Hurts would remain the starting quarterback for Alabama. In the season opener against Louisville, Tagovailoa was the starter. Hurts came into the game in a rotation. He had 70 passing yards in the 51–14 victory. Tagovailoa was officially named the starter going into the next game against Arkansas State. In a backup role, Hurts earned significant playing time in the 2018 season.


title: Jalen Hurts

text: In the 2018 SEC Championship Game, he relieved an injured Tagovailoa and led the team to a comeback victory against Georgia. Alabama moved to 13–0 and secured a spot in the Playoff.


title: Jalen Hurts

text: On January 16, 2019, Hurts announced via social media that he would be transferring to the University of Oklahoma for his final year of eligibility. As a graduate transfer, he was eligible to play for the 2019 season.


title: Jalen Hurts

text: In his first game as a Sooner on September 1, 2019, Hurts shattered Oklahoma's single-game yardage record in a debut (previously held by Baker Mayfield when he put up 396 yards of total offense against Akron in 2015), putting up 508 yards of total offense against Houston. On September 28, in a 55–14 victory over Texas Tech, he had 415 passing yards, three passing touchdowns, and one interception to go along with nine carries for 70 rushing yards and a rushing touchdown. Hurts helped lead Oklahoma to a 7–0 start to the season. The team's first setback came against Kansas State on October 26. In the 48–41 loss, Hurts passed for 395 yards and a passing touchdown to go along with 19 carries for 96 rushing yards and three rushing touchdowns. Hurts helped lead Oklahoma to a Big 12 Championship and a spot in the College Football Playoff. The Sooners' season ended with a 63–28 loss to LSU in the 2019 Peach Bowl. Hurts recorded a successful season with the Sooners, recording 3,851 passing yards, 32 passing touchdowns, and eight interceptions to go along with 1,298 rushing yards and 20 rushing touchdowns. He finished second in the Heisman Trophy voting to Joe Burrow.


title: Jalen Hurts

text: The Philadelphia Eagles selected Hurts 53rd overall in the second round of the 2020 NFL Draft. After originally being named as the third string quarterback behind Nate Sudfeld, he gained the backup position at Week 2, mainly so he could be used for quarterback running plays or as a decoy. On December 6, 2020, Hurts came on in relief of Carson Wentz, who was benched due to ineffective play, against the Green Bay Packers. In this Week 13 matchup, Hurts threw his career first passing touchdown to Greg Ward and finished the game with 109 passing yards with a touchdown and an interception in the 30–16 loss. On December 8, 2020, Hurts was named the starter for their Week 14 game against the New Orleans Saints. In his first NFL start, Hurts completed 17 of 30 passing attempts for 167 passing yards and one touchdown, leading the Eagles to a 24–21 win. Hurts also added 106 rushing yards, totaling 273 all purpose yards. On December 20, 2020, in Week 15 against the Arizona Cardinals, Hurts finished with 338 passing yards, three passing touchdowns, 63 rushing yards and one rushing touchdown in the 33–26 loss.


title: Jalen Hurts

text: In Week 16 against the Dallas Cowboys, Hurts threw for 342 yards, one touchdown, two interceptions, and rushed for 69 yards during the 37–17 loss.


title: Jalen Hurts

text: In Week 17 against the Washington Football Team on "Sunday Night Football", Hurts threw for 72 yards and an interception and rushed for 34 yards and two touchdowns before being benched in favor of Sudfeld during the 20–14 loss. Hurts' benching drew allegations of Eagles head coach Doug Pederson attempting to deliberately lose the game; Pederson was fired shortly afterwards.


title: Jalen Hurts

text: Before the start of the regular season, Hurts switched his jersey number to No. 1, which had become available with the departure of punter Cameron Johnston. On August 31, 2021, Hurts was named the starter for the regular season by new head coach Nick Sirianni. In the season opener, on the road against the Atlanta Falcons, Hurts led the Eagles to a 32–6 victory, throwing for three touchdowns and a passer rating of 126.4. During a Week 12 loss to the New York Giants, Hurts suffered an ankle injury which kept him out for the following week's game against the New York Jets. The Eagles won that game 33–18 led by backup quarterback Gardner Minshew. Hurts returned after the bye week in a Week 15 matchup against Washington en route to a 27–17 victory. Hurts helped lead the Eagles to a playoff berth after defeating the Washington Football Team 20–16 in week 17 and with wins from the San Francisco 49ers and Green Bay Packers later that day. On December 23, 2021, Hurts was named a 2021 Pro Bowl NFC alternate. In the 2021 season, Hurts finished with 3,144 passing yards, 16 passing touchdowns, and nine interceptions to go along with 139 carries for 784 rushing yards and ten rushing touchdowns. He led all quarterbacks in rushing yards and rushing touchdowns in the 2021 season.


title: Jalen Hurts

text: In the against the Tampa Bay Buccaneers, Hurts threw for 258 yards and a touchdown, but fumbled once and threw two interceptions in the 31–15 loss.


title: Jalen Hurts

text: Entering the season, many people questioned whether or not Hurts would prove to be the new franchise quarterback for the Eagles. Many people did note that 2022 would be the first time since high school that Hurts would have the same offensive coordinator across two seasons.


title: Jalen Hurts

text: In the season opener against the Detroit Lions, Hurts threw for 243 yards and rushed for 90 yards and one touchdown in the 38–35 win. In Week 2 on "Monday Night Football" against the Minnesota Vikings, Hurts threw for 333 yards, one touchdown and one interception with a 83.9% completion and a 108.7 rating in the 24–7 win. Hurts followed the "Monday Night" win over the Vikings with another impressive performance against the division rival Washington Commanders. Hurts completed 22 of his 35 pass attempts for 340 yards and three touchdowns in a 24–8 victory to improve to 3–0 on the season. For his performance, Hurts was named NFC Offensive Player of Month for September, becoming the first Eagles player to win the award since 2017. In Week 5, against the Arizona Cardinals, he had 239 passing yards, 61 rushing yards, and two rushing touchdowns in the 20–17 victory. After a 29-17 victory over the Houston Texans on Thursday Night Football, Hurts became the first Eagles quarterback to lead the team to an 8-0 record. With a Week 14 win over the New York Giants, Hurts led the Eagles to a consecutive playoff berth. After a Week 15 win over the Chicago Bears, Hurts became the youngest quarterback in NFL history to lead a team to a 13-1 start. He would also tie Randall Cunningham for the most total TDs in a season 35 to just 5 interceptions. A day after the win over the Bears, it was revealed that Jalen had sprained his throwing shoulder.


title: Jalen Hurts

text: Hurts' parents are Pamela and Averion Hurts. Hurts has two siblings: a younger sister, Kynnedy, and an older brother, Averion, named after their father. Jalen's brother, Averion, was the starting quarterback for Texas Southern University and is now a college football coach at the University of Alabama. As of Hurts' freshman year, one of his parents attended his football game every week, while the other attended Averion's game.


title: Jalen Hurts

text: Hurts is a Christian. He has said, “I keep God at the center of everything. I give Him all the praise, I lean on Him all the time. And I know that everything unfolds the way it’s supposed to.”


title: Jalen Hurts

text: On June 20, 2022, Hurts filed for a trademark for the phrase "HURTS SO GOOD." The Trademark registry says that it will be used for a clothing line that includes "mens, womens and children's clothing, namely shirts, jackets, sweatshirts, pants, shorts, vests, gloves, socks, sweaters, underwear, skirts, hats and belts."


title: Carbon monoxide

text: Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simplest molecule of the oxocarbon family. In coordination complexes the carbon monoxide ligand is called carbonyl. It is a key ingredient in many processes in industrial chemistry.


title: Carbon monoxide

text: The most common source of carbon monoxide is the partial combustion of carbon-containing compounds, when insufficient oxygen or heat is present to produce carbon dioxide. There are also numerous environmental and biological sources that generate and emit a significant amount of carbon monoxide. It is important in the production of many compounds, including drugs, fragrances, and fuels. Upon emission into the atmosphere, carbon monoxide affects several processes that contribute to climate change.


title: Carbon monoxide

text: Carbon monoxide has important biological roles across phylogenetic kingdoms. It is produced by many organisms, including humans. In mammalian physiology, carbon monoxide is a classical example of hormesis where low concentrations serve as an endogenous neurotransmitter (gasotransmitter) and high concentrations are toxic resulting in carbon monoxide poisoning. It is isoelectronic with cyanide anion CN.


title: Carbon monoxide

text: Humans have maintained a complex relationship with carbon monoxide since first learning to control fire circa 800,000 BC. Early humans probably discovered the toxicity of carbon monoxide poisoning upon introducing fire into their dwellings. The early development of metallurgy and smelting technologies emerging circa 6,000 BC through the Bronze Age likewise plagued humankind from carbon monoxide exposure. Apart from the toxicity of carbon monoxide, indigenous Native Americans may have experienced the neuroactive properties of carbon monoxide through shamanistic fireside rituals.


title: Carbon monoxide

text: Early civilizations developed mythological tales to explain the origin of fire, such as Prometheus from Greek mythology who shared fire with humans. Aristotle (384–322 BC) first recorded that burning coals produced toxic fumes. Greek physician Galen (129–199 AD) speculated that there was a change in the composition of the air that caused harm when inhaled, and many others of the era developed a basis of knowledge about carbon monoxide in the context of coal fume toxicity. Cleopatra may have died from carbon monoxide poisoning.


title: Carbon monoxide

text: Georg Ernst Stahl mentioned "carbonarii halitus" in 1697 in reference to toxic vapors thought to be carbon monoxide. Friedrich Hoffmann conducted the first modern scientific investigation into carbon monoxide poisoning from coal in 1716. Herman Boerhaave conducted the first scientific experiments on the effect of carbon monoxide (coal fumes) on animals in the 1730s.


title: Carbon monoxide

text: Joseph Priestley is considered to have first synthesized carbon monoxide in 1772. Carl Wilhelm Scheele similarly isolated carbon monoxide from charcoal in 1773 and thought it could be the carbonic entity making fumes toxic. Torbern Bergman isolated carbon monoxide from oxalic acid in 1775. Later in 1776, the French chemist produced CO by heating zinc oxide with coke, but mistakenly concluded that the gaseous product was hydrogen, as it burned with a blue flame. In the presence of oxygen, including atmospheric concentrations, carbon monoxide burns with a blue flame, producing carbon dioxide. Antoine Lavoisier conducted similar inconclusive experiments to Lassone in 1777. The gas was identified as a compound containing carbon and oxygen by William Cruickshank in 1800.


title: Carbon monoxide

text: Thomas Beddoes and James Watt recognized carbon monoxide (as hydrocarbonate) to brighten venous blood in 1793. Watt suggested coal fumes could act as an antidote to the oxygen in blood, and Beddoes and Watt likewise suggested hydrocarbonate has a greater affinity for animal fiber than oxygen in 1796. In 1854, Adrien Chenot similarly suggested carbon monoxide to remove the oxygen from blood and then be oxidized by the body to carbon dioxide. The mechanism for carbon monoxide poisoning is widely credited to Claude Bernard whose memoirs beginning in 1846 and published in 1857 phrased, "prevents arterials blood from becoming venous". Felix Hoppe-Seyler independently published similar conclusions in the following year.


title: Carbon monoxide

text: Carbon monoxide gained recognition as an invaluable reagent in the 1900s. Three industrial processes illustrate its evolution in industry. In the Fischer–Tropsch process, coal and related carbon-rich feedstocks are converted into liquid fuels via the intermediacy of CO. Originally developed as part of the German war effort to compensate for their lack of domestic petroleum, this technology continues today. Also in Germany, a mixture of CO and hydrogen was found to combine with olefins to give aldehydes. This process, called hydroformylation, is used to produce many large scale chemicals such as surfactants as well as specialty compounds that are popular fragrances and drugs. For example, CO is used in the production of vitamin A. In a third major process, attributed to researchers at Monsanto, CO combines with methanol to give acetic acid. Most acetic acid is produced by the Cativa process. Hydroformylation and the acetic acid syntheses are two of myriad carbonylation processes.


title: Carbon monoxide

text: Carbon monoxide is the simplest oxocarbon and is isoelectronic with other triply-bonded diatomic species possessing 10 valence electrons, including the cyanide anion, the nitrosonium cation, boron monofluoride and molecular nitrogen. It has a molar mass of 28.0, which, according to the ideal gas law, makes it slightly less dense than air, whose average molar mass is 28.8.


title: Carbon monoxide

text: The carbon and oxygen are connected by a triple bond that consists of a net two pi bonds and one sigma bond. The bond length between the carbon atom and the oxygen atom is 112.8 pm. This bond length is consistent with a triple bond, as in molecular nitrogen (N), which has a similar bond length (109.76 pm) and nearly the same molecular mass. Carbon–oxygen double bonds are significantly longer, 120.8 pm in formaldehyde, for example. The boiling point (82 K) and melting point (68 K) are very similar to those of N (77 K and 63 K, respectively). The bond-dissociation energy of 1072 kJ/mol is stronger than that of N (942 kJ/mol) and represents the strongest chemical bond known.


title: Carbon monoxide

text: The ground electronic state of carbon monoxide is a singlet state since there are no unpaired electrons.


title: Carbon monoxide

text: Carbon and oxygen together have a total of 10 electrons in the valence shell. Following the octet rule for both carbon and oxygen, the two atoms form a triple bond, with six shared electrons in three bonding molecular orbitals, rather than the usual double bond found in organic carbonyl compounds. Since four of the shared electrons come from the oxygen atom and only two from carbon, one bonding orbital is occupied by two electrons from oxygen, forming a dative or dipolar bond. This causes a C←O polarization of the molecule, with a small negative charge on carbon and a small positive charge on oxygen. The other two bonding orbitals are each occupied by one electron from carbon and one from oxygen, forming (polar) covalent bonds with a reverse C→O polarization since oxygen is more electronegative than carbon. In the free carbon monoxide molecule, a net negative charge δ remains at the carbon end and the molecule has a small dipole moment of 0.122 D.


title: Carbon monoxide

text: The molecule is therefore asymmetric: oxygen has more electron density than carbon and is also slightly positively charged compared to carbon being negative. By contrast, the isoelectronic dinitrogen molecule has no dipole moment.


title: Carbon monoxide

text: Carbon monoxide has a computed fractional bond order of 2.6, indicating that the "third" bond is important but constitutes somewhat less than a full bond. Thus, in valence bond terms, C≡O is the most important structure, while :C=O is non-octet, but has a neutral formal charge on each atom and represents the second most important resonance contributor. Because of the lone pair and divalence of carbon in this resonance structure, carbon monoxide is often considered to be an extraordinarily stabilized carbene. Isocyanides are compounds in which the O is replaced by an NR (R = alkyl or aryl) group and have a similar bonding scheme.


title: Carbon monoxide

text: If carbon monoxide acts as a ligand, the polarity of the dipole may reverse with a net negative charge on the oxygen end, depending on the structure of the coordination complex.


title: Carbon monoxide

text: Theoretical and experimental studies show that, despite the greater electronegativity of oxygen, the dipole moment points from the more-negative carbon end to the more-positive oxygen end. The three bonds are in fact polar covalent bonds that are strongly polarized. The calculated polarization toward the oxygen atom is 71% for the σ-bond and 77% for both π-bonds.


title: Carbon monoxide

text: The oxidation state of carbon in carbon monoxide is +2 in each of these structures. It is calculated by counting all the bonding electrons as belonging to the more electronegative oxygen. Only the two non-bonding electrons on carbon are assigned to carbon. In this count, carbon then has only two valence electrons in the molecule compared to four in the free atom.


title: Carbon monoxide

text: Carbon monoxide occurs in various natural and artificial environments. Photochemical degradation of plant matter for example generates an estimated 60 billion kilograms/year. Typical concentrations in parts per million are as follows:


title: Carbon monoxide

text: Carbon monoxide (CO) is present in small amounts (about 80 ppb) in the Earth's atmosphere. Most of the rest comes from chemical reactions with organic compounds emitted by human activities and natural origins due to photochemical reactions in the troposphere that generate about 5 × 10 kilograms per year. Other natural sources of CO include volcanoes, forest and bushfires, and other miscellaneous forms of combustion such as fossil fuels. Small amounts are also emitted from the ocean, and from geological activity because carbon monoxide occurs dissolved in molten volcanic rock at high pressures in the Earth's mantle. Because natural sources of carbon monoxide vary from year to year, it is difficult to accurately measure natural emissions of the gas.


title: Carbon monoxide

text: Carbon monoxide has an indirect effect on radiative forcing by elevating concentrations of direct greenhouse gases, including methane and tropospheric ozone. CO can react chemically with other atmospheric constituents (primarily the hydroxyl radical, OH) that would otherwise destroy methane. Through natural processes in the atmosphere, it is oxidized to carbon dioxide and ozone. Carbon monoxide is short-lived in the atmosphere (with an average lifetime of about one to two months), and spatially variable in concentration.


title: Carbon monoxide

text: Due to its long lifetime in the mid-troposphere, carbon monoxide is also used as a tracer for pollutant plumes.


title: Carbon monoxide

text: Carbon monoxide is a temporary atmospheric pollutant in some urban areas, chiefly from the exhaust of internal combustion engines (including vehicles, portable and back-up generators, lawnmowers, power washers, etc.), but also from incomplete combustion of various other fuels (including wood, coal, charcoal, oil, paraffin, propane, natural gas, and trash).


title: Carbon monoxide

text: Carbon monoxide is, along with aldehydes, part of the series of cycles of chemical reactions that form photochemical smog. It reacts with hydroxyl radical (OH) to produce a radical intermediate HOCO, which transfers rapidly its radical hydrogen to O to form peroxy radical (HO) and carbon dioxide (). Peroxy radical subsequently reacts with nitrogen oxide (NO) to form nitrogen dioxide (NO) and hydroxyl radical. NO gives O(P) via photolysis, thereby forming O following reaction with O.


title: Carbon monoxide

text: Since hydroxyl radical is formed during the formation of NO, the balance of the sequence of chemical reactions starting with carbon monoxide and leading to the formation of ozone is:


title: Carbon monoxide

text: Although the creation of NO is the critical step leading to low level ozone formation, it also increases this ozone in another, somewhat mutually exclusive way, by reducing the quantity of NO that is available to react with ozone.


title: Carbon monoxide

text: In closed environments, the concentration of carbon monoxide can rise to lethal levels. On average, 170 people in the United States die every year from carbon monoxide produced by non-automotive consumer products. These products include malfunctioning fuel-burning appliances such as furnaces, ranges, water heaters, and gas and kerosene room heaters; engine-powered equipment such as portable generators (and cars left running in attached garages); fireplaces; and charcoal that is burned in homes and other enclosed areas. Many deaths have occurred during power outages due to severe weather such as Hurricane Katrina and the 2021 Texas power crisis.


title: Carbon monoxide

text: Miners refer to carbon monoxide as "whitedamp" or the "silent killer". It can be found in confined areas of poor ventilation in both surface mines and underground mines. The most common sources of carbon monoxide in mining operations are the internal combustion engine and explosives; however, in coal mines, carbon monoxide can also be found due to the low-temperature oxidation of coal. The idiom "Canary in the coal mine" pertained to an early warning of a carbon monoxide presence.


title: Carbon monoxide

text: Beyond Earth, carbon monoxide is the second-most common diatomic molecule in the interstellar medium, after molecular hydrogen. Because of its asymmetry, this polar molecule produces far brighter spectral lines than the hydrogen molecule, making CO much easier to detect. Interstellar CO was first detected with radio telescopes in 1970. It is now the most commonly used tracer of molecular gas in general in the interstellar medium of galaxies, as molecular hydrogen can only be detected using ultraviolet light, which requires space telescopes. Carbon monoxide observations provide much of the information about the molecular clouds in which most stars form.


title: Carbon monoxide

text: Beta Pictoris, the second brightest star in the constellation Pictor, shows an excess of infrared emission compared to normal stars of its type, which is caused by large quantities of dust and gas (including carbon monoxide) near the star.


title: Carbon monoxide

text: In the atmosphere of Venus carbon monoxide occurs as a result of the photodissociation of carbon dioxide by electromagnetic radiation of wavelengths shorter than 169 nm. It has also been identified spectroscopically on the surface of Neptune's moon Triton.


title: Carbon monoxide

text: Solid carbon monoxide is a component of comets. The volatile or "ice" component of Halley's Comet is about 15% CO. At room temperature and at atmospheric pressure, carbon monoxide is actually only metastable (see Boudouard reaction) and the same is true at low temperatures where CO and are solid, but nevertheless it can exist for billions of years in comets. There is very little CO in the atmosphere of Pluto, which seems to have been formed from comets. This may be because there is (or was) liquid water inside Pluto.


title: Carbon monoxide

text: This is called the water-gas shift reaction when occurring in the gas phase, but it can also take place (very slowly) in an aqueous solution.


title: Carbon monoxide

text: If the hydrogen partial pressure is high enough (for instance in an underground sea), formic acid will be formed:


title: Carbon monoxide

text: Carbon monoxide has a wide range of functions across all disciplines of chemistry. The four premier categories of reactivity involve metal-carbonyl catalysis, radical chemistry, cation and anion chemistries.


title: Carbon monoxide

text: Most metals form coordination complexes containing covalently attached carbon monoxide. Only metals in lower oxidation states will complex with carbon monoxide ligands. This is because there must be sufficient electron density to facilitate back-donation from the metal d-orbital, to the π* molecular orbital from CO. The lone pair on the carbon atom in CO also donates electron density to the d on the metal to form a sigma bond. This electron donation is also exhibited with the cis effect, or the labilization of CO ligands in the cis position. Nickel carbonyl, for example, forms by the direct combination of carbon monoxide and nickel metal:


title: Carbon monoxide

text: For this reason, nickel in any tubing or part must not come into prolonged contact with carbon monoxide. Nickel carbonyl decomposes readily back to Ni and CO upon contact with hot surfaces, and this method is used for the industrial purification of nickel in the Mond process.


title: Carbon monoxide

text: In nickel carbonyl and other carbonyls, the electron pair on the carbon interacts with the metal; the carbon monoxide donates the electron pair to the metal. In these situations, carbon monoxide is called the carbonyl ligand. One of the most important metal carbonyls is iron pentacarbonyl, Fe(CO):


title: Carbon monoxide

text: Many metal–CO complexes are prepared by decarbonylation of organic solvents, not from CO. For instance, iridium trichloride and triphenylphosphine react in boiling 2-methoxyethanol or DMF to afford IrCl(CO)(PPh).


title: Carbon monoxide

text: In the presence of strong acids and water, carbon monoxide reacts with alkenes to form carboxylic acids in a process known as the Koch–Haaf reaction. In the Gattermann–Koch reaction, arenes are converted to benzaldehyde derivatives in the presence of AlCl and HCl. Organolithium compounds (e.g. butyl lithium) react with carbon monoxide, but these reactions have little scientific use.


title: Carbon monoxide

text: Although CO reacts with carbocations and carbanions, it is relatively nonreactive toward organic compounds without the intervention of metal catalysts.