Patent ID: 12228592

The detailed description explains embodiments of the disclosure, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION

Embodiments of the present disclosure provide for a sensor for measuring electrical characteristics that is light in weight to be coupled to a pole mounted AC electrical power line. Embodiments of the present disclosure further provide for a sensor that measures electrical characteristics of distribution voltage applications (e.g. up to 52 kV) while outputting a low energy signal (e.g. 0 to 10 VAC). Still further embodiments of the present disclosure provide a desired level of accuracy over a large temperature range (e.g. ˜+/−0.1% over 100 C).

It should be appreciated that while embodiments herein may refer to a sensor system that measures AC electrical characteristics on an electrical power line, this is for exemplary purposes and the claims should not be so limited. In other embodiments the sensor system may be used in other applications, such as measuring direct current (DC) electrical characteristics or in non-pole mounted power line applications, such as on subterranean electrical distribution power lines for example.

Referring now toFIG.1, an embodiment is shown of a utility electrical distribution system20. The utility system20includes one or more power sources22connected in parallel to a main transmission system24. The power sources22may include, but are not limited to: coal, nuclear, natural gas, or incineration power plants. Additionally, the power source22may include one or more facilities that generate electricity based on renewable energy sources, such as but not limited to hydroelectric, solar, or wind turbine power plants. It should be appreciated that additional components such as transformers, switchgear, fuses and the like (not shown) may be incorporated into the utility system20as needed to ensure the efficient operation of the system. The utility system20is typically interconnected with one or more other utility networks to allow the transfer of electrical power into or out of the utility system20.

The main transmission system24typically consists of high transmission voltage power lines, anywhere from 69 KV to 500 KV for example, and associated transmission and distribution equipment which carry the electrical power from the point of production at the power source22to the end users located on local electrical distribution systems26,29. The local distribution systems26,29are connected to the main distribution system by area substations32which reduce transmission voltage to distribution levels such as 13 KV, 27 KV or 33 KV for example, sometimes referred to as medium voltage power lines. Area Substations32typically contain one or more transformers, switching, protection, and control equipment. Area Substations32all include circuit breakers to interrupt faults such as short circuits or over-load currents that may occur. Area substations32may also include equipment such as fuses, surge protection, controls, meters, capacitors, and load tap changers for voltage regulation.

The area substations32connect to one or more local electrical distribution systems, such as local distribution system26, for example, that provides electrical power to a commercial area having end users such as an office building34or a manufacturing facility36. In an embodiment, the area substation32may have two or more feeder circuits that provide electrical power to different feeder circuit branches27,28of the local distribution system26.

The residential distribution system29includes one or more residential buildings46and light industrial or commercial operations. Similar to the commercial distribution network26, the residential distribution system29is divided into multiple branch feeders30,31that are fed by the area substation32. In an embodiment, the local distribution system29is arranged such that approximately up to 6 MVA of power is provided on each branch circuit for electrical loads such as residential buildings.

It should be appreciated that it may be desirable for the utility to monitor the voltage and current of the utility system20at various locations between the power source22and the end-user building34,46(i.e. loads). Traditionally, the measurement of electrical characteristics of the power line, such as medium voltage power lines for example, are performed by discrete sensors. For example, measurement of current is performed using a sensor having a current transformer. These sensors are mounted directly to the uninsulated medium voltage power line. However, these sensors are arranged in close proximity to the live or “hot” power line. Thus it is difficult for utility personnel (sometimes referred to as linemen) to install or remove the sensors using common tools utilized by utility personnel, such as a so called hot-stick or shotgun stick. As used herein, the terms “hot-stick” or “shotgun stick” refers to a tool utilized by linemen that includes an elongated insulated body having a movable operating hook at one end. The operating hook is actuated by a sliding trigger mechanism at an opposite end of the body from the hook. The shotgun stick allows, in some circumstances, for linemen to manipulate or move electrical components that are in contact with live power lines. It should further be appreciated that these discrete sensors that use current transformers are heavy and place mechanical stresses on the electrical power lines. As a result, the locations where the current transformer based sensors are mounted must be carefully chosen to avoid adversely impacting the durability of the electrical power lines.

Referring now toFIGS.2A and2B, a sensor system200is provided that is accurate and light weight enough to be installed-on or removed-from a live power line, such as a medium voltage power line having a voltage of 13 KV, 27 KV or 33 KV for example. The sensor system200includes a pair of clamps202,204that are coupled by a substantially rigid support bar206. In an embodiment, the support bar206is made from an electrically conductive material, such as aluminum for example. Centrally disposed on the support bar206is an insulator body208. It should be appreciated that the insulator body208electrically isolates the support bar206and the clamps202,204from the rest of the sensor system200. The support bar206, insulator body208, and clamps202,204cooperate to prevent the housings/portions218,220from rotating or tilting relative to the conductor coupled to the clamps202,204.

In an embodiment, one of the clamps202or204is electrically isolated from the support bar206to prevent electrical current from flowing through the support bar206. In one embodiment, shown inFIG.8, the clamps202,204are both formed from a body203that electrically isolates the clamping portion of the clamps from the support bar206. In this embodiment, a conductor205electrically couples the clamp202to the support bar206. Since the support bar206is electrically coupled to the conductor being measured in at least one location, undesirable electrical discharge activities can be avoided when the conductor is energized to high voltage.

Coupled to the insulator body opposite the support bar206is an electronics housing210. As will be discussed in more detail herein, the electronics housing210includes electronics212(digital or analog) that receive signals from a plurality of magnetic field point sensors and outputs a low energy signal (e.g. 0 to 10 VAC) to a communications line214. It should be appreciated that the communications line214may transmit to a suitable computing device (either locally or remote) that is configured to monitor the electrical characteristics of the AC power line.

Coupled to the electronics housing210is a ring assembly216. In the illustrated embodiment, the ring assembly216is comprised of a lower ring portion218and an upper ring portion220. The lower ring portion218is coupled to the electronics housing210. The upper ring portion220is slidably coupled to the lower ring portion218such that the upper ring portion220may be moved from a first position (FIG.2B) to a second position (FIG.6) to define an opening between an end600of the lower ring portion218and an end602of the upper ring portion220to define a gap604. As will be discussed in more detail herein, by moving the upper ring portion220to the second position, the utility personnel can install the sensor system200on a live or active electrical power line by passing the electrical power line through the gap604. Each of the lower ring portion218and the upper ring portion includes a tab222having an opening224therein. The opening is sized to receive an end effector of a hot-stick or shotgun stick to allow the utility personnel to engage the sensor system200the portions218,220.

The upper ring portion220is comprising of a semi-circular housing300(FIG.3A) made from an insulative material, such as high density polyethylene for example. In an embodiment, the housing300is made of a sufficient thickness to maintain electrical isolation of the components within the housing300in the event the sensor fell on the ac electrical power line. The housing300includes a hollow interior302that includes a sensor circuit board304. As discussed herein, the sensor circuit board304includes a plurality of magnetic field point sensors. The magnetic field point sensors may be model A1308 manufactured by Allegro Microsystems for example. In the illustrated embodiment, the sensor circuit board304has a semi-circular shape that corresponds with the housing300. In an embodiment, the magnetic field point sensors are mounted on an FR-4 printed circuit board material which is coupled to an aluminum support member. It has been found that this provides advantages in reducing the thermal expansion of the sensing circle resulting in a temperature error of about +/−0.1% per 100 C. In an embodiment, the sensor circuit board304is disposed within insulating potting material306, such as platinum-cure silicone rubber for example. Surrounding the potting material is an electrostatic shield308, such as a faraday cage for example.

In an embodiment, the lower ring portion218is divided into two halve350,352(FIG.3B). The first half350is constructed in a similar manner to the upper ring portion220. The first half350includes a semicircular first housing354having a hollow interior356. Disposed within the hollow interior356is a sensor circuit board358having a semi-circular shape that corresponds to the shape of the first housing354. In an embodiment, the sensor circuit board358is disposed in an insulative potting material360that is surrounded by an electrostatic shield362, such as a faraday cage for example. In an embodiment, the magnetic field point sensors of sensor circuit board358may be mounted on an FR-4 printed circuit board material which is coupled to an optional aluminum support member (not shown) in the same manner as sensor circuit board304. As will be discussed in more detail herein, the sensor circuit board358is electrically coupled to the sensor circuit board304. The first housing354is made from an electrically insulative material, such as high density polyethylene for example. In an embodiment, the first housing is u-shaped with the open side enclosed by the second half352. In other embodiments, the first housing354includes walls that extend about/enclose the sensor circuit board358.

In an embodiment, the second half352comprises a second housing364. The second housing364has a semi-circular shape that corresponds with the first half350. In an embodiment, the second housing364is made from an insulative material, such as high density polyethylene. The walls of the second housing364define an interior portion366that is sized and shaped to receive the upper ring portion220when the upper ring portion is slid from the first position to the second position.

Referring now toFIG.4A-4C, an embodiment is shown of the arrangement of the magnetic field point sensors400. In an embodiment, the magnetic field point sensors400are arranged into a first set of sensors402and a second set of sensors404. The first set of sensors being associated with the lower ring portion218and the second set of sensors being associated with the upper ring portion220. The first set of sensors are arranged in a first plane406and the second set of sensors are arranged in a second plane408. As shown inFIG.4BandFIG.4C, the individual magnetic field point sensors, such as sensors410A-410H for example, each have a different orientation of the sensing axis. In an embodiment, the sensors410C,410E,410G (e.g. alternating sensors) have a sensing axis that is tangent to an arc on the planes406,408. The alternate sensors, such as sensors410D,410F,410H the sensing axis is both tangent to the arc (FIG.4C) and oppositely oriented relative to the sensors410C,410E,401G. In some embodiments, sensors near the ends of the upper and lower rings (e.g. sensors410B,410C) may also be oriented on an angle to the planes406,408(FIG.4B). This angled orientation compensates for the small gap that exists between the two planes406,408. It should be appreciated that whileFIG.4Conly shows the second set of sensors404, the first set of sensors402are arranged in a similar manner. Further, it should be appreciated that while the illustrated embodiments show a particular number of magnetic field point sensors400, the number and spacing of the sensors may be varied depending on the application.

Providing sensors402,404provides advantages in reducing noise. The alternating of sensor orientations provides two electrical signals that are differential with respect to the detected magnetic field. In addition, the two electrical signals have common mode signals due to electrical noise present in the electronic circuit and power supply. By calculating the difference between the two signals, the result is sensitive to the magnetic field being sensed, but the common mode signals cancel, resulting in a lower noise floor on the output signal.

Referring now toFIG.5a schematic illustration is shown of the electrical connections of the sensor system500. It should be appreciated that the sensor system500may be physically constructed in a similar manner to sensor system200. In this embodiment, the sensor system500includes a first set of magnetic field point sensors502and a second set of magnetic field point sensors504. Each of the sets of magnetic field point sensors502,504being arranged on a circuit board506,508in a semi-circular shape. The circuit boards506,508are each surrounded by an faraday cage or electrostatic shield510,512. The electrostatic shields510,512are coupled to a ground514.

The circuit boards506,508are configured to route signals from the magnetic field point sensors502,504to an interface member516via conductors518,520. In an embodiment, the interface member516is configured to receive and average the signals from the magnetic field point sensors502,504and output a low energy (0-10 VAC) signal indicating the level of current passing through the conductor being monitored. The signals are transmitted via conductors518to a data acquisition system that digitizes the signal, stores values and communicates the data to local or remote users. The interface member516is further configured to receive an input electrical power (12 VDC) via conductor520.

Referring now toFIG.6, an embodiment of the lower ring portion606and the upper ring portion608is shown in the open or second position. In this position a gap604is defined between an end600of the lower ring portion606and an end602of the upper ring portion608. It should be appreciated that the gap allows the sensor system to be installed over an active or “hot” power line. When the upper ring portion608is moved to the second position from the first position, the upper ring portion608slides within a channel (e.g. interior portion366). In an embodiment, the circuit board within the upper ring portion608includes a conductor610that extends into the channel (e.g. interior portion366) and exits via a centrally located opening on an inner diameter of the lower ring portion606. In an embodiment that lower ring portion606includes a slot612that is sized to receive the conductor610when the upper ring portion608is slid into the lower ring portion606. In other words, the slot612provides a relief area where the conductor610can be positioned when the upper ring portion608is fully inserted into the lower ring portion606.

Referring now toFIG.7AandFIG.7B, another embodiment of a sensor system700for measuring electrical characteristics on a pole mounted electrical power line is shown. In this embodiment, the upper ring portion702and lower ring portion704are coupled by guides706. The clamps708, bar710and insulator712are arranged the same as sensor system200. Within the upper ring portion702and lower ring portion704, the sensor system700includes a circuit board with a plurality of magnetic field point sensors in the same manner as sensor system200.

In this embodiment, the upper ring portion702slides next to the lower ring portions704along a path defined by guides706. The conductor714from the circuit board in the upper ring portion702exits the upper ring portion702adjacent the tab716and enters the electronics housing718at a port720. The electronics housing718further includes a second port722that connects to a cable724that provides both input electrical power (12 VDC) and output the low energy signal indicating the value of the electrical characteristic (e.g. current or voltage) that is present in the electrical power line being monitored. The electronics housing718further includes a ground connection726.

The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the disclosure is provided in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments of the disclosure have been described, it is to be understood that the exemplary embodiment(s) may include only some of the described exemplary aspects. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.