Abstract:
Control circuits for breaker control switches with a time-delay function and associated methods of making and using these devices to prevent an aurora event are disclosed. An exemplary control circuit may include a signaling device configured to provide a close signal for a circuit breaker to close; a timer configured to complete a countdown after the circuit breaker is opened; and a switch configured to close the circuit breaker after the countdown is complete and when the close signal is provided by the device. This may prevent engaging a piece of equipment with the power grid when the piece of equipment is out of phase or frequency with the power grid, which often leads to significant damage or destruction of the piece of equipment. Other embodiments are described.

Description:
FIELD 
       [0001]    This application relates generally to safety equipment for use with power equipment attached to a power supply grid. More specifically, this application relates to systems and methods for preventing power equipment from being destroyed by an aurora event. 
       BACKGROUND 
       [0002]    Rotating AC electrical equipment connected to the power grid, such as motors and generators, spin in sync or in phase with the grid power. If the rotating equipment becomes out of phase (for example, by a rapid stop-start sequence) or by connecting to the grid without synchronizing the relevant phases, the equipment will be forced almost instantaneously into phase with the grid. This abrupt change is known as an aurora event. The North American Electric Reliability Corporation&#39;s (NERC) recognized this vulnerability and issued a Recommendation to Industry in 2011 to the industry to encourage solutions to prevent Aurora events. 
         [0003]    Aurora events can result in exceptionally high torques being placed on mechanical components of rotating equipment and associated loads, such as transmissions, pumps, gear boxes, compressors, shafts, turbines, etc. This torque can result in the mechanical components far exceeding their design limitations. Damage or destruction of the rotating equipment and attached devices often results from aurora events. Similarly, electrical windings and components may be damaged by exceptionally high loading during the instant phase realignment event. 
         [0004]    High power equipment such as large motors and generators are particularly vulnerable to aurora events because of the high mass rotating components of high power equipment. For example, an 800 kW generator requires substantial mechanical components to transfer mechanical energy and power through the generator and will, therefore, generally have large spinning and moving components that have very high inertial energy when rotating or otherwise moving. When an aurora event occurs, the already rotating equipment attempts to rapidly adjust to a different rotation phase or speed, creating massive torque as the inertial energy of the moving components resists the change to the different phase or speed. Since F=ma, a quick change in speed produces a very high acceleration (a) multiplied by the mass (m) of the moving components creates a very high force (F), which can be exhibited through torque in rotating components. The high force and torque can easily overcome design limitations and destroy critical components of the motor or generator and attached load devices. 
       SUMMARY 
       [0005]    This application relates to control circuits for breaker control switches with a time-delay function and associated methods of making and using these devices to prevent an aurora event. In some embodiments, an exemplary control circuit may include a signaling device configured to provide a close signal for a circuit breaker to close, a timer configured to complete a countdown after the circuit breaker is opened, and a switch configured to close the circuit breaker after the countdown is complete and when the close signal is provided by the device. 
         [0006]    In some embodiments, the signaling device may be a manual switch or a computer. The circuit breaker may connect power equipment to a power supply grid. The power equipment may be three-phase power equipment. In other embodiments, the countdown may be determined based on the time required for the power equipment to completely stop after being disconnected from the power grid. The switch may be an AND logic gate, and the control circuit may include an integrated circuit, with the timer and the switch each as components of the integrated circuit. 
         [0007]    The signaling device may be further configured to provide a trip signal. The countdown may begin when the signaling device provides the trip signal. In other embodiments, the countdown may begin when the circuit breaker is opened. 
         [0008]    In some embodiments, a method of controlling a circuit breaker may include the steps of opening the circuit breaker; starting a countdown; generating a close signal associated with a command to close the circuit breaker; closing the circuit breaker after the countdown is complete and after the signal associated with the command to close the circuit breaker is generated; and resetting the countdown. The close signal may be associated with the command to close the circuit breaker is generated by a manual switch. 
         [0009]    The method may further include generating a trip signal associated with a trip mode of the circuit breaker. The countdown may begin when trip signal is generated or when the circuit breaker is opened. In some embodiments, the close signal may be generated by a remote computer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The following description can be better understood in light of the Figures, in which: 
           [0011]      FIG. 1  shows a schematic illustration of an exemplary embodiment of a circuit for a breaker control switch with a time-delay close function used with equipment; 
           [0012]      FIG. 2  shows a schematic illustration of an exemplary embodiment of a circuit for a breaker control switch with a time-delay close function used with equipment; 
           [0013]      FIG. 3  shows an exemplary manual switch for use with a breaker control switch with a time-delay function; 
           [0014]      FIG. 4  shows a schematic illustration of an exemplary embodiment of a circuit for a breaker control switch with a time-delay close function used with equipment; and 
           [0015]      FIG. 5  shows a flow chart depicting some embodiments of a method for using an exemplary breaker control switch a time delay function. 
       
    
    
       [0016]    The Figures illustrate specific aspects of exemplary breaker control switches with a time-delay function and methods for making and using such devices as described below. Together with the following description, the Figures demonstrate and explain the principles of the structures, methods, and principles described herein. In the drawings, the thickness and size of components may be exaggerated or otherwise modified for clarity. The same reference numerals in different drawings represent the same element, and thus their descriptions will not be repeated. Furthermore, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the described devices. Moreover, the Figures may show simplified or partial views, and the dimensions of elements in the Figures may be exaggerated or otherwise not in proportion for clarity. 
       DETAILED DESCRIPTION 
       [0017]    The following description supplies specific details in order to provide a thorough understanding. Nevertheless, the skilled artisan would understand that the described breaker control switches with a time-delay function and methods of making and using the breaker control switches can be implemented and used without employing these specific details. Indeed, the breaker control switches and associated methods can be placed into practice by modifying the illustrated devices and methods and can be used in conjunction with any other apparatus and techniques conventionally used in the industry. For example, while the description below focuses on methods for making and using a digitally enhanced manual switch and solid-state components to control the breaker control switch with a time-delay function, other components such as electronic switches, and programmed signals may be used. 
         [0018]    In addition, as the terms on, attached to, or coupled to are used below, for clarity of describing function, one object (e.g., a material, a layer, a substrate, etc.) can be on, attached to, or coupled to another object regardless of whether the one object is directly on, attached, or coupled to the other object or there are one or more intervening objects between the one object and the other object. Also, directions (e.g., above, below, top, bottom, side, up, down, under, over, upper, lower, horizontal, vertical, “x,” “y,” “z,” etc.), if provided, are relative and provided solely by way of example and for ease of illustration and discussion and not by way of limitation. In addition, where reference is made to a list of elements (e.g., elements a, b, c), such reference is intended to include any one of the listed elements by itself, any combination of less than all of the listed elements, and/or a combination of all of the listed elements. 
         [0019]    Some embodiments of the breaker control switch with a time-delay function and associated methods of making and using these switches are described in detail herein and illustrated in the Figures.  FIG. 1  illustrates a schematic representation of a control circuit  100  for a breaker control switch with a time-delay function in operative connection with power equipment  190  and a power grid  10 . The control circuit  100  may be used to control the power supply or the connection between any electrical equipment  190  and any power grid  10  through the circuit breaker  150 . The power grid  10  may be a complete electrical network or a part of an electrical network that supplies any type of power. The power grid  10  may be any power supply grid such as various types of public utility power grids used throughout the world, as well as private grids created by or for individual companies, compounds, and instillations. 
         [0020]    The control circuit  100  may include any integrated circuit  110 . In the embodiments shown in  FIG. 2 , the control circuit  100  and the integrated circuit  110  may include an AND logic gate  120  (or other component or components that perform the same function such as a microprocessor or other similar device), as well as any other components to effect the functionality of a breaker control switch with a time-delay function to prevent aurora events, as described herein. The integrated circuit  110  may require a time-delay for manual or automated attempts to close a circuit connecting the power equipment  190  to the grid  10 . By providing a time delay, the power equipment  190  may be given time enough to stop prior to any attempt to reconnect to the grid, thereby preventing an aurora event. 
         [0021]    The AND logic gate  120  may be any component or combination of components capable of effectuating an AND logic function. In other words, both input signals may be present to allow an output signal. In this case, both a timer signal indicating that a countdown is complete and a signal to close the circuit breaker may be required before a signal to close the circuit breaker is sent to close the circuit breaker. Other similar components may be used in place of an AND gate, for example, a comparator, OP Amps, or even programming logic through a microprocessor on controller may perform the function of the AND logic gate  120 , as described herein. 
         [0022]    Many pieces of power equipment  190 , particularly power equipment requiring very high current to run, include a soft-start or a safe start circuits that allow the power equipment  190  to start properly without damaging it. The power equipment  190  may require a significant current draw when starting, such that the power draw during start-up may be several times the power required for the power equipment  190  to run at the designed functional loading. 
         [0023]    When connecting generators to the power grid  10 , the generator is generally brought up to speed slowly and then synchronized before connecting the generator to the grid to avoid damage to the generator. If the power equipment  190  is improperly disconnected and reconnected without synchronizing or allowing the start circuits to function properly, significant damage to the power equipment  190  may result. 
         [0024]    As shown in  FIGS. 2 and 3 , when the switch  130  is set to a trip (or off) position, the circuit breaker  150  disconnects the power equipment  190  from the grid  10 . In order to close the circuit breaker  150  to connect the power equipment  190  to the grid  10 , the knob  131  of switch  130  may first be set to trip before being moved to the closed position, indicating that the power equipment  190  is connected to the grid  10 . When the switch  130  is on the trip position, the trip signal  132  and the timer signal  134  may be provided to the integrated circuit  110  and the trip signal LED  142  and the timer LED  144  may be lit, indicating that the timer  124  is counting. Once the timer  124  has counted an appropriate time interval, the timer LED  144  may be turned off and a signal may be sent to the AND logic gate  120  to permit the output close signal  148  to be sent if the close signal  136  is also present at the AND logic gate  120 . As such, in some embodiments, the AND logic gate  120  and the integrated circuit  110  function as a timed switch to only allow the output close  148  signal to close the circuit breaker  150  when the close signal  136  is present and the timer  124  has performed the required countdown. 
         [0025]    When the knob  131  of the switch  130  is moved to the close position, the close signal  136  may be provided to the integrated circuit  110  and to the AND gate  120 . If both inputs to AND gate  120  are present, output close signal  148  may be sent to circuit breaker  150  to close the connection between power equipment  190  and the grid  10 . Additionally, timer  124  may be reset once the circuit breaker  150  is closed such that the timer  124  will automatically delay any subsequent attempts to close the circuit breaker  150  after it trips or is opened. In some embodiments, the knob  131  may be biased such that it cannot be set to the close position, but merely toggled to the close position and then be maintained in the trip position during normal operations to allow circuit breaker  150  to trip as needed to prevent overload of the circuit. 
         [0026]    The control circuit  100  also contains a timer  124 . The timer  124  may provide a time delay of any desired length, which can be selected depending on the time required to either stop or sync rotating components of the power equipment  190 . For example, a 300 hp pump chiller motor may require at least two minutes to completely stop to allow the start circuit to perform as designed when the chiller motor is restarted. The rotating internal components and any components attached to the chiller motor may be required to be stopped completely before being connected to three-phase power to ensure proper start-up and to avoid aurora events that would otherwise damage or destroy the chiller motor or other components. In such embodiments, the timer  124  would have at least a two minute time limit before the control circuit  100  would allow a user or automated signal to affect the breaker  150  to close. 
         [0027]    In some configurations, the time delay may be sufficient to allow a generator to re-synchronize with the power grid  10  before being connected back to it. Generally, the power equipment  190  requiring the control circuit  100  may be multi-phase equipment such as large generators, chiller motors, electric arc furnaces, compressors, pumps, renewable energy systems, synchronous motors, large induction motors, etc., since the electrical power equipment  190  is most efficient when running on multiple phases, such as the common 3-phase systems of most power grids. In some embodiments, the input power  138  for the control circuit  100  and integrated circuit  110  may be 125V DC or 48V DC, or any other suitable voltage input. 
         [0028]    In some embodiments, the timer  124  may be programmable to a desired time limit, or the timer  124  may be set to a particular time limit. In other embodiments, the timer  124  may be replaced with other sensors that sense when it is safe to close the circuit breaker  150 . For example, a sensor may signal that all rotating components of the power equipment  190  have stopped, or may signal when phases are properly aligned when connecting a generator to the power grid  10 . In such embodiments, the timer signal  134  could be replaced with a sensor signal to indicate to the AND logic gate  120  when the output close signal  148  may be sent to the circuit breaker  150  to close the circuit. 
         [0029]    In other embodiments, the timer  124  may automatically perform its countdown whenever the circuit breaker  150  is opened. In these embodiments, when the power equipment  190  has been sitting idle for some long period of time, the time interval will have already been accomplished and the circuit breaker  150  may be started immediately as desired by the user. For example, the timer  124  may be activated when the switch  130  is in the open position and would countdown, extinguishing the timer LED  144  once completed. In these embodiments, the timer  124  would not need to countdown again when the switch  130  is moved to the trip position. 
         [0030]    In the embodiments illustrated in  FIG. 4 , a controller  230  may be used in place of integrated circuit  110  to control the circuit breaker  150 . In such embodiments, the controller  230  may be accessed remotely (or indirectly) by a remote device  260  through a network  210  or it may be accessed directly. In some configurations, the controller  230  may also directly control the function of the power equipment  190 . The controller  230  may include wireless communication capabilities or may be connected to a remote device  260 , network  210 , power equipment  190 , and/or circuit breaker  150  through any wired or wireless communications. The network  210  may be the internet, a wide area network, a local area network, or any other electronic network that allows multiple devices to communicate electronically. The controller  230  may be a local computer, microprocessor, plant server, or any other device capable of electronically controlling the control circuit  100  and/or the circuit breaker  150 . 
         [0031]    In some configurations, the remote device  260  may connect to the controller  230 , the network  210 , or both using any communications protocols or systems sufficient to transmit instructions to the controller  230 . The remote device  260  may be any device that can send control signals to the controller  230 . For example, the remote device  260  may be a notebook computer, a workstation, a mobile phone, a tablet computer, a remote server, etc. And the remote device  260  may also function in a delayed manner, running a script automatically and/or remotely. 
         [0032]    In some instances, an unauthorized user may set a malicious code or program, such as a virus, trojan, or worm in the controller  230 , any component of the network  210 , or on a remote device  260  that may connect with the controller  230 . The malicious code or program may function such that it would signal to maliciously open and then close the circuit breaker  150  with the design of destroying the power equipment  190  and cause an aurora event. In these instances, the malicious signal may be sent at a pre-determined time or when the remote device  260  is connected with the controller  230 . When used, the control circuit  100  would prevent an aurora event due to such a malicious signal. In other configurations, the control circuit  100  could also prevent user error in rapidly opening and closing the circuit breaker  150  that may cause an aurora event. 
         [0033]      FIG. 5  illustrates embodiments of a method for using the control circuit  100  to prevent damage to the power equipment  190 . Once the circuit breaker  150  is opened, the process illustrated in  FIG. 5  may be employed to prevent such damage. As shown in box  1 , when a user attempts to close the circuit to attach power equipment to the grid, the timer  124  may be activated in box  2 . Then, the trip signal LED  142  representing a trip function can be illuminated (as shown in box  3 ) and the timer LED  144  representing the activated timer countdown may be illuminated (as shown in box  4 ). Once the timer  124  completes its countdown, as shown in box  5 , the timer LED  144  representing the timer countdown may be extinguished (as shown in box  6 ) and the output close LED  146  representing a readiness of control circuit  100  to close circuit breaker  150  may be activated, as shown in box  7 . 
         [0034]    If the user has set switch  130  to close, as shown in box  8 , it will close once the timed countdown is complete and the timer LED  144  is extinguished. Otherwise, the circuit breaker  150  will close once the timer  124  in complete, allowing the timer signal  134  to pass to the AND gate  120 , and the switch  130  is set to close, sending the close signal  136  to the AND gate  120 . Once the circuit breaker  150  is closed, the timer  124  may automatically reset (as shown in box  9 ) so that in the event of a tripped breaker or a user or a signal otherwise opening the breaker  150 , it will not be able to be closed until the timer  124  again performs the timed countdown to completion. 
         [0035]    High power equipment is usually expensive and can be very vulnerable to damage or destruction from an aurora event. The costs to repair or replace high power equipment can easily accumulate to hundreds of thousands (or millions) of dollars for large generators, motors, compressors, pumps, gearboxes, etc. And an initial failure of a single component in the high power equipment can cause subsequent failure of attached components or device, cascading such damage through rotating power equipment and significantly increasing costs of repair. As such, the control circuit  100  described herein and other embodiments consistent with this disclosure may be very valuable to companies and individuals for protection of their power equipment. 
         [0036]    In addition to any previously indicated modification, numerous other variations and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of this description, and appended claims are intended to cover such modifications and arrangements. Thus, while the information has been described above with particularity and detail in connection with what is presently deemed to be the most practical and preferred aspects, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, form, function, manner of operation, and use may be made without departing from the principles and concepts set forth herein. Also, as used herein, the examples and embodiments, in all respects, are meant to be illustrative only and should not be construed to be limiting in any manner.