Voltage sensor for an electrical switching device and electrical switching device comprising it

Abstract

A circuit breaker includes a capacitive voltage sensor within its insulating housing. The voltage sensor includes a capacitor between the terminals of the circuit breaker, the capacitor being adjacent to a low potential surface provided by a coil of a current sensor. The capacitor is dome shaped. The voltage sensor does not significantly increase the size or weight of the circuit breaker and is reliable and accurate.

Description

Technical Field

[0001] This invention relates to voltage detection in electrical switching devices, particularly voltage detection in circuit breakers and reclosers. Background Technology

[0002] Voltage sensors are typically configured for circuit breakers and reclosers to detect the voltage on their power supply side, and in some applications, voltage sensors are also configured on their load side. Conventional voltage sensors can be located externally to the circuit breaker or recloser body and connected between the relevant circuit breaker / recloser terminals and electrical ground. Such sensors significantly increase the weight and size of the entire system, including the circuit breaker or recloser, and can reduce reliability due to the additional wiring from the external sensor to the measurement system. Furthermore, these sensors increase the overall installation cost of the system.

[0003] The above issues need to be addressed. Summary of the Invention

[0004] A first aspect of the present invention provides an electrical switching device, the electrical switching device comprising:

[0005] The first electrical terminal connected to the first electrical contact;

[0006] The second electrical terminal connected to the second electrical contact;

[0007] A means for actuating a second electrical contact between an open state and a closed state; and

[0008] A voltage sensor used to detect the voltage at the first electrical terminal.

[0009] The voltage sensor includes a voltage divider having a voltage input connected to the first electrical terminal, a voltage output between the voltage input and a voltage reference, and a first capacitor connected between the voltage input and the voltage output.

[0010] Switching devices typically include an electrically insulating housing, preferably an electrically insulating molded part, wherein at least the first and second electrical contacts and the first capacitor are disposed within the housing, and the first capacitor is located between the first and second terminals within the housing. The first terminal may include a conductive member located within the housing and extending between the first electrical contact and an exposed first terminal connector, and the second terminal includes a conductive member located within the housing and extending between the second contact and an exposed second terminal connector, wherein the first capacitor is positioned between the conductive members. The conductive members of the first terminal and the conductive members of the second terminal are typically perpendicular or substantially perpendicular to each other.

[0011] Preferably, the first capacitor is located closer to the conductive member of the second terminal than the conductive member of the first terminal, and more preferably, it is located adjacent to the conductive member of the second terminal.

[0012] A preferred embodiment includes at least one current sensing coil located near a conductive member of the second terminal, and the first capacitor is located adjacent to the at least one current sensing coil.

[0013] The first capacitor may be disposed on and electrically connected to a conductive support member, which is located within the housing and is in communication with a first terminal. The first capacitor may be disposed at the end of the support member, and its shape and size may conform to the periphery of the end of the support member. The first terminal may include a conductive member located within the housing and extending between the first electrical contact and the exposed first terminal connector. The support member is mechanically connected to or integrally formed with the conductive member to enable communication between the support member and the conductive member. The support member may extend from the conductive member of the first terminal toward a second terminal, and the first capacitor is disposed on the support member, preferably at the end of the support member, located between the first and second terminals. The support member includes a base portion extending horizontally from the conductive member of the first terminal, and an end portion extending vertically or obliquely from the base portion toward the second terminal.

[0014] The first capacitor typically includes first and second electrical conductors, preferably in the form of dielectrically separated, respective conductive plates, wherein the first electrical conductor is electrically connected and optionally mechanically connected to a support, preferably to an end of the support. The first conductor and the support may have at least one corresponding complementary surface, preferably at least one corresponding cylindrical surface, to facilitate their mutual engagement.

[0015] In a preferred embodiment, the first capacitor is dome-shaped. Preferably, the first capacitor includes first and second conductors, which are respectively conductive plates separated by a dielectric, wherein the first and second conductors and the intermediate dielectric are all dome-shaped. Preferably, the first capacitor includes an annular wall portion, which is preferably cylindrical. Preferably, the first capacitor is symmetrical about its central axis. Preferably, the first capacitor is U-shaped in cross-section parallel to its central axis. Preferably, the first capacitor is circular in cross-section perpendicular to its central axis. The annular wall portion, preferably the inner surface of the annular wall, can be mechanically and electrically connected to a support, preferably to the free end of the support. The first conductor can be electrically and mechanically connected to the support, preferably to the free end of the support.

[0016] In a preferred embodiment, the voltage divider is a capacitive voltage divider, preferably including a second capacitor connected between the voltage output and the voltage reference.

[0017] A preferred embodiment of the switching device includes a housing, preferably an electrically insulating housing, and at least the first and second electrical contacts and the first capacitor are disposed within the housing.

[0018] In a preferred embodiment, the switching device includes a structure having a low, preferably zero, or near-zero potential during use, and wherein the first capacitor is located near the structure. The low-potential structure is preferably mounted within the housing. The second terminal preferably carries the low-potential structure.

[0019] In a preferred embodiment, the second terminal includes a conductive member located within the housing and extending between the second contact and the exposed second terminal connector, wherein the conductive member carries the low potential structure.

[0020] Optionally, the low-potential structure includes an electrically insulating sleeve or coil located around the second terminal.

[0021] In a preferred embodiment, the low-potential structure includes the coil of a current sensor.

[0022] In a preferred embodiment, at least the first capacitor is embedded or enclosed in the electrical insulating material, which is preferably part of the housing of the switching device.

[0023] In a typical embodiment, the first and second electrical contacts are part of a vacuum interrupter.

[0024] In some embodiments, the switching device is a circuit breaker.

[0025] A second aspect of the present invention provides an electrical switching device, the electrical switching device comprising:

[0026] The first electrical terminal connected to the first electrical contact;

[0027] The second electrical terminal connected to the second electrical contact;

[0028] Means for actuating the second electrical contact between an open state and a closed state; and

[0029] A voltage sensor used to detect the voltage at the first electrical terminal.

[0030] The voltage sensor includes a voltage divider having a voltage input connected to the first electrical terminal, a voltage output between the voltage input and a voltage reference, and a first capacitor connected between the voltage input and the voltage output, wherein the first capacitor is dome-shaped.

[0031] A third aspect of the invention provides a voltage sensor including a voltage divider having a voltage input, a voltage output connection between the voltage input and a voltage reference, and a first capacitor connected between the voltage input and the voltage output, and being dome-shaped. Preferably, the first capacitor typically includes first and second electrical conductors, the two conductors being in the form of respective conductive plates separated by a dielectric, wherein the first and second electrical conductors and the intermediate dielectric are all dome-shaped.

[0032] The present invention can be embodied as a circuit breaker including a capacitive voltage sensor located within its insulating housing. The voltage sensor includes a capacitor located between the terminals of the circuit breaker, adjacent to a low-potential surface provided by a coil of a current sensor. The capacitor is preferably dome-shaped.

[0033] The preferred embodiments of the present invention have the advantage of being able to monitor the voltage of a circuit breaker or recloser without increasing the overall size of the circuit breaker / recloser poles and with only a slight increase in mass. Furthermore, compared to conventional solutions, reliability is improved due to the integration of the voltage sensor and its associated circuitry into the main circuit breaker / recloser poles.

[0034] Other advantageous aspects of the invention will become apparent to those skilled in the art after reading the following description of specific embodiments and referring to the accompanying drawings. Attached Figure Description

[0035] Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0036] Figure 1 This is a side sectional view of a vacuum circuit breaker illustrating one aspect of the present invention;

[0037] Figure 2 This is a side sectional view of a capacitor, which is mounted on... Figure 1 A portion of the circuit breaker and a portion of the voltage sensor embodying another aspect of the invention; and

[0038] Figure 3 This is a schematic circuit diagram of a voltage sensor. Figure 2 The capacitor is one part of it. Detailed Implementation

[0039] Now, please refer specifically to the attached diagram. Figure 1The figure generally illustrates an automatically operating electrical switching device marked 10. The illustrated switching device 10 is of the type commonly referred to as a circuit breaker. Switching device 10 is configured to operate automatically under fault conditions (e.g., current overload or short circuit) to protect the circuit it inhabits (not shown) during use. It achieves this by disconnecting the circuit in response to fault detection. As described in more detail below, switching device 10 includes at least one voltage sensor for monitoring the voltage at its respective one or both terminals. This voltage sensor, or each voltage sensor, can be used to control the operation of switching device 10. In some embodiments, switching device 10 can be manually reset (e.g., by a mechanical or user-controlled manually activated electromechanical means (not shown)) or automatically reset (typically in response to the switching device 10 detecting the disappearance of a fault and / or the expiration of a threshold time from startup). Automatically reset switching devices are generally referred to as reclosers. Figure 1 The switching device 10 in the embodiments is a vacuum circuit breaker. However, it should be understood that the invention is not limited to vacuum circuit breakers, and can alternatively be used with other types of circuit breakers, reclosers, or other electrical switching devices, and the same or similar descriptions as described above apply, as will be apparent to those skilled in the art. The switching device 10 is particularly suitable for alternating current systems, especially alternating current power supply systems. Depending on the application, the switching device 10 can be configured for use with low voltage (LV), medium voltage (LV), or high voltage (HV). Typically, a corresponding instance of the switching device 10 is provided for each phase or pole of the alternating current power supplied by the alternating current power supply system.

[0040] Circuit breaker 10 includes a first electrical terminal 12 and a second electrical terminal 14, through which the circuit breaker can be connected to an external circuit (not shown). In application, one of the electrical terminals 12 or 14 is connected to a power source or line / voltage, while the other electrical terminal 14 or 12 is connected to an electrical load. The terminal connected to the power source or line / voltage during use can be considered as the power source or line side of circuit breaker 10, or as part of the power source or line side, while the terminal connected to the load during use can be considered as the load side of circuit breaker 10, or as part of the load side.

[0041] The first terminal 12 is electrically connected to and can be integrally formed with the first electrical contact 16. The first contact 16 is typically fixed and can be referred to as the fixed contact 16. The second terminal 14 is electrically connected to the second electrical contact 18. In this example, the second terminal is electrically connected to the contact 18 via the electrical pickup assembly 20. The second contact 18 can be in an open state (e.g., ...). Figure 1The circuit breaker 10 moves between a closed state (shown) and a closed state (not shown), in which the second contact 18 is in electrical contact with the first contact 16. The open state of contact 18 corresponds to the open or open state of circuit breaker 10 (in which state circuit breaker 10 interrupts the current between terminals 12, 14). The closed state of contact 18 corresponds to the closed or engaged state of circuit breaker 10 (in which state current can flow between terminals 12, 14 through contacts 16, 18). In the illustrated embodiment, contacts 16, 18 are part of vacuum interrupter 22 and are thus located within vacuum chamber 24.

[0042] Movement of contact 18 between its open and closed states is achieved by an actuation device comprising an actuator 26 coupled to contact 18. In the illustrated embodiment, actuator 26 is an electromagnetic actuator, or other conventional forms, such as electromechanical or piezoelectric actuators, may be employed. In the illustrated embodiment, mechanical coupling 28 couples actuator 26 and contact 18 and is configured to convert movement of actuator 26 into a corresponding movement of contact 18. In this embodiment, coupling 28 converts linear movement of actuator 26 into linear movement of contact 18. In some embodiments, actuator 26 is operable to move contact 18 from a closed state to an open state or from an open state to a closed state. Alternatively, movement of contact 18 from an open state to a closed state can be achieved manually, in which case the actuation device may include a lever or other manual operating device for achieving this purpose. Movement of contact 18 from a closed state to an open state typically operates automatically in response to the detection of a fault condition. The movement of the contact from the open state to the closed state can be determined manually or automatically depending on the application.

[0043] At least a portion of the circuit breaker 10 is disposed within the housing 30. At least a portion, and preferably all of the housing 30, is constructed of an electrically insulating material, such as ceramic, rubber, plastic, or resin (e.g., epoxy or polyester). The housing 30 may include molded parts or other solid structures in which some or all components of the circuit breaker 10 are embedded, or in other words, some or all components of the circuit breaker are molded into or embedded within an insulating material. For example, the vacuum interrupter 22, the voltage sensor 40 (or at least a portion of the voltage sensor 40), the support 56, and the rods 12B and 14B may be embedded within the housing. Figure 1In this embodiment, both the coupling mechanism 28 and the current sensor 34 are embedded within the housing. Alternatively or additionally, all or part of the housing 30 may be hollow, defining one or more cavities to accommodate at least some components of the circuit breaker 10. When the housing 30 is hollow, its surface is covered with a non-conductive or electrically insulating material. Typically, at least contacts 16, 18 are disposed within the housing 30, and in the example of a vacuum circuit breaker (as shown), the vacuum interrupter 22 is enclosed within the housing 30. Terminals 12, 14 are also disposed within the housing 30, exposing corresponding connector portions 12A, 14A of terminals 12, 14 through the housing 30 to allow connection of the circuit breaker 10 to external circuits and devices where appropriate. Typically, each terminal 12, 14 includes a conductive rod 12B, 14B, or other conductive member extending between the corresponding contact 16, 18 and the corresponding connector portion 12A, 12B. The contacts 12A and 14B of the rods 12B and 14B and the terminals 12 and 14 can be conveniently formed integrally or separately and electrically connected. In a typical arrangement, the rods 12B and 14B extend non-parallel to each other, typically perpendicular or substantially perpendicular to each other. The rod 12A of the first terminal 12 typically extends along or parallel to the axis of motion of the movable contact 18.

[0044] In a preferred embodiment, the pickup assembly 20 is disposed within the housing 30. The coupling device 28 may also be disposed within the housing 30. The actuator 26 may be disposed within the housing 30, or may be mechanically fixed to or otherwise connected to the housing 30 as shown. For example, the actuator 26 may be disposed in the base unit 32 connected to the housing 30.

[0045] Circuit breaker 10 may include a current sensor 34 for detecting current at a second terminal 14. The current sensor 34 may include one or more coils 36 disposed around the conductive portion of terminal 14, conveniently around rod 14B. The coils 36 typically include electrically insulated wire. The current sensor 34 may be of any conventional type, including, for example, a Rogowski coil or a current transformer. In a preferred embodiment, the current sensor 34 is included in a housing 30. The current sensor 34 is connected to a controller 35 to send a signal characterizing the current level flowing in terminal 14. The controller 35 responds to the signal from the sensor 34 to control the operation of circuit breaker 10. The controller 35 may include or be connected to circuitry (not shown) for operating actuator 26 (in the illustrated embodiment, this may include circuitry for controlling the energization of the electromagnetic coil of actuator 26). In particular, the controller 35 may include means for determining whether a current or voltage level (where applicable) is above a threshold, and if so, the controller 35 actuates actuator 26 to open contacts 16, 18. In some embodiments, controller 35 may be configured to actuate actuator 26 to close contacts 16, 18 according to one or more criteria, such as determining that an electrical fault has been cleared or that a certain time has elapsed (e.g., in embodiments where device 10 is a recloser). Controller 35 may take any convenient form, such as including one or more suitably configured electrical circuits or suitably programmed microprocessors, microcontrollers, or other processors. At least part or optionally all of controller 35 may be included in circuit breaker 10, for example in housing 30, or preferably in base unit 32. Alternatively, controller 35 may be configured to be separate from circuit breaker 10 and may communicate with circuit breaker via any conventional optical, wired, or wireless transmission means to perform any or all of the operations described herein. More generally, current sensor 34 may be connected to controller 35 in any conventional manner, typically a wired connection. For this purpose, circuit breaker 10 may include conduit 38, preferably within housing 30, for carrying wires or other connectors from sensor 34 to controller. In the illustrated embodiment, conduit 38 carries wires from coil 36 to a controller assuming it is located in base unit 32. Conduit 38 may also carry wires from sensors 40, 60 to controller 35.

[0046] The circuit breaker 10 includes a voltage sensor 40 for detecting the voltage at the first terminal 12. The voltage sensor 40 includes a voltage divider, preferably a capacitive voltage divider. Figure 3A capacitive voltage divider suitable for a voltage sensor 40 is shown. The voltage sensor 40 has a first circuit section between a voltage input 41 and a voltage output 54, and a second circuit section between the voltage output 54 and a voltage reference Verf, which is conveniently electrically grounded or another reference voltage point. The voltage input 41 is connected to a first terminal 12. The first and second circuit sections include respective impedances such that the voltage at the output 54 depends on the voltage at terminal 12 and the associated impedances of the first and second circuit sections. In a preferred embodiment, the impedance of the first circuit is a capacitance C. HV Preferably, the impedance is provided by the first capacitor 42. The impedance of the second circuit section is the capacitance C. LV Preferably, a second capacitor 50 is used. A first capacitor 42 is connected between a voltage input 41 and a voltage output 54. A second capacitor 50 is connected between the voltage output 54 and ground. The capacitor 42 thus has a first terminal 44 electrically connected to the first terminal 12 of the circuit breaker 10, and a second terminal 46 electrically connected to the first terminal 48 of the second capacitor 50. The second terminal 52 of the second capacitor 50 is electrically connected to ground. The output 54 provides an output voltage that depends on the voltage at terminal 12 and the corresponding capacitance C of capacitors 42 and 50. HV C LV .

[0047] The output voltage at output 54 is lower than the input voltage at terminal 12. Output 54 is provided to controller 35, which is configured to measure or otherwise detect or evaluate the voltage at output 54. For this purpose, output 54 leads to controller 35. Controller 35 may include means for determining whether the voltage at output 54 exceeds a threshold, and / or whether one or more other characteristics of the voltage signal meet one or more other criteria, which may vary depending on the embodiment. Optionally, based on the measured current and / or voltage (if applicable), other electrical parameters of the network may also be calculated, such as power, energy, impedance, phase shift, etc. These parameters may be used for relay protection and substation automation. Power and energy measurements may be used for commercial and technical accounting of electricity. Controller 35 responds to a signal from sensor 40, or in other words, to a signal from output 54, to control the operation of circuit breaker 10. Controller 35 may be configured to actuate actuator 26 to open contacts 16, 18, typically when a voltage at output 54 is found to be higher than a threshold. In some embodiments, the controller 35 may be configured to operate the actuator 26 to close contacts 16, 18 according to one or more criteria, such as finding that the voltage at output 54 is below or at a threshold, or exceeds a certain time (e.g., in an embodiment where device 10 is a recloser).

[0048] In a preferred embodiment, the capacitance C of the second capacitor 50 LV The capacitance C is higher than that of the first capacitor 42. HV In a typical embodiment where terminal 12 is connected to the high-voltage (HV) line, capacitor C is selected. LV C HV The value is set so that the voltage at output 54 is at a level compatible with the voltage received by controller 35. For example, according to an embodiment, the typical voltage level at terminal 12 may be 10kV, 24kV, or 36kV, while at output 54, the typical voltage level may be in the range of millivolts or hundreds of volts.

[0049] In an alternative embodiment (not shown), the voltage sensor 40 may include an alternative form of voltage divider, particularly one with an alternative circuit topology. Figure 3 The voltage divider shown is an example. For instance, capacitor C... HV C LV One or two of the capacitors can be configured as one or more capacitors, such as a single capacitor or a network consisting of more than one capacitor. For example, one or two of capacitors 42 and 50 can be implemented as two or more capacitors in series, or two or more capacitors in parallel, or other arrangements of capacitors. Optionally, the second circuit section may include one or more capacitors in parallel and / or in series for thermal compensation of the voltage divider. Optionally, one or more resistors may be included in the voltage divider. For example, one or more resistors may be provided in the second circuit section to compensate for phase shift.

[0050] In a preferred embodiment, the first capacitor 42 is located within the housing 30. Advantageously, the first capacitor 42 is located between the first and second terminals 12, 14. In a preferred embodiment, the first capacitor 42 is disposed on and electrically connected to the conductive support 56. The conductive support 56 is electrically connected to the first terminal 12. Conveniently, the support 56 is mechanically connected to or integrally formed with the rod 12B, such that the support 56 and the rod 12B are electrically connected to each other. In a preferred embodiment, the support 56 extends laterally from the rod 12B, i.e., in a direction perpendicular to or inclined to the rod 12B. Preferably, the support 56 extends from the rod 12B in a direction toward the second terminal 14. The support 56 can extend from the rod 12B in a direction parallel to the second terminal 14. The support 56 includes an end 56A that preferably extends toward the rod 14B toward the second terminal 14. In a preferred embodiment, the support 56 includes a base portion 56B extending laterally from the rod 12B and an end portion 56A extending vertically or obliquely from the base portion 56B toward the rod 14B. The support 56 may be L-shaped. The support 56 may include any conductive structure, such as one or more rods and / or plates capable of supporting the capacitor 42, and is typically metallic, but may also be formed of any other convenient conductive material. In an alternative embodiment, alternative support devices (not shown) may be provided to support the capacitor 42 within the housing 30, for example, by supporting the capacitor 42 from the rod 14B. In this case, the capacitor 42 may be electrically connected to the terminal 12 via one or more wires. The support 56 or other support device is also advantageously disposed within the housing 30. In a preferred embodiment, the assembly of the support 56 or other support device and the first capacitor 42 is located in the region between the first and second terminals 12, 14 within the housing 30. It is recommended that the capacitor 42 be disposed between the first and second terminals 12, 14, as this effectively utilizes the space between the terminals 12, 14, thereby improving the compactness of the circuit breaker 10.

[0051] Advantageously, capacitor 42 is located adjacent to a surface within housing 30 whose potential is relatively lower than the operating voltage of device 10 (i.e., the standard operating voltage at terminals 12, 14), preferably at least an order of magnitude lower (i.e., a power of 10). Capacitor 42 is preferably located adjacent to a surface within housing that has zero potential (or near zero potential, preferably 10 volts or less, more preferably 1 volt or less) during operation. This can be achieved by attaching capacitor 42 to any structure having a surface with zero or near zero potential during operation, such as 10 volts or less, preferably 1 volt or less. Surfaces or structures with zero or low potential are typically formed of conductive material and may be electrically insulating. Preferred arrangements ensure that there is no large potential difference (e.g., zero potential difference, or at most 1 volt, or at most 10 volts) between the zero or low potential structure / surface and the capacitor (especially terminal 42B of capacitor 42 connected to sensor output 54). This arrangement ensures high accuracy of sensor 40 and provides it with good dielectric strength. If capacitor 42 is not adjacent to a zero or low potential surface, the relatively high potential at terminals 12, 14 will affect the accuracy of sensor 40 measurements. Capacitor 42 may be adjacent to any convenient zero or low potential structure within housing 30, or to a zero or low potential surface of any structure. In a typical embodiment, capacitor 42, particularly its terminals (42B), is located at a distance of at most 100 mm, preferably at most 50 mm, and more preferably at most 25 mm from a relatively zero or low potential surface.

[0052] In the preferred embodiment, the coil 36 of the current sensor 34 has a zero or low potential during use (the actual value may depend on the operating mode of the current sensor 34 and the current flowing through terminal 14). Therefore, in the preferred embodiment, the capacitor 42, particularly conductor 42B, is located near the coil 36 of the current sensor 34. Advantageously, the capacitor 42 is close enough to the coil 36 to create a low potential difference (e.g., 10 volts or less), zero potential difference, or essentially zero potential difference (e.g., less than 1 volt) between the capacitor 42 (or at least conductor 42B) and the surface of the coil 36. In use, the coil 36 typically has a zero potential, and conductor 42B of the capacitor 42 has a near-zero potential at output 54. This improves the dielectric strength and accuracy of the capacitor 42. In a typical embodiment, the capacitor 42, particularly the terminal (42B) of the capacitor 42, is located at a distance of at most 100 mm from the coil 36, preferably at most 50 mm, and more preferably at most 25 mm. In alternative embodiments (not shown), such as in embodiments without coil 36, other zero-potential or low-potential surfaces for positioning the nearby capacitor 42 are disposed within the housing 30, preferably between terminals 12 and 14. For example, an electrically insulating sleeve (not shown) of conductive material may be disposed around rod 14B and grounded (or connected to another voltage reference), and capacitor 42 may be located adjacent to the sleeve.

[0053] In a preferred embodiment, the first capacitor 42 is shaped like a ring cap for mounting around the end 57 of the support 56. The first capacitor 42 is preferably dome-shaped, but can also be described as bowl-shaped or bell-shaped. Preferably, the first capacitor 42 is symmetrical or substantially symmetrical about its central axis. In a preferred embodiment, the cross-section of the first capacitor 42 in any plane parallel to its central axis is U-shaped.

[0054] The first capacitor 42 includes first and second electrical conductors 42A and 42B separated by a dielectric 42C. Each conductor 42A and 42B preferably includes a conductive plate, which is preferably dome-shaped or other circular. The conductors 42A and 42B are dimensioned such that conductor 42A fits inside conductor 42B. Conductor 42B provides the outer surface of the dome capacitor 42, while conductor 42A provides the inner surface of the dome capacitor. Conductors 42A and 42B are typically metallic, but may also be formed of any other suitable conductive material. The dielectric 42C may include any suitable conventional dielectric material, such as glass, ceramic, or plastic.

[0055] The first conductor 42A is electrically connected to the support 56. Therefore, the first conductor 42A provides the first terminal 44 of the capacitor 42. The first conductor 42A is also mechanically connected to the support 56, preferably to end 56A. In a preferred embodiment, end 56A has a free end 57, where the first conductor 42A is located and mechanically and electrically connected to the free end 57. The first conductor 42A can be connected to the support using any convenient coupling device (not shown), such as a conductive sealing ring or welding. Optionally, the first conductor 42A and the support 56 have at least one corresponding complementary surface to facilitate their mutual engagement.

[0056] The second conductor 42B is electrically connected to the first terminal 48 of the second capacitor 50. Conveniently, the second conductor 42B serves as the second terminal 46 of the first capacitor 42. The second conductor 42B can be electrically connected to the first terminal 48 of the second capacitor 50 by any convenient means, such as via a wire, cable, or other electrical conductor. For example, the second conductor 42B and the first terminal 48 can be electrically connected together at the controller 35. In the illustrated embodiment, a wire 58 connects the second conductor 42B to an electrical point (not shown) at the controller 35, which serves as the output 54 of the voltage divider. The second capacitor 50 is not shown. Figure 1 The capacitor 50 can be placed in any convenient location, such as within housing 30, in base portion 32, or in controller 35, and its first terminal is connected to the same electrical point to which conductor 58 is connected at controller 35. The second terminal 52 of capacitor 50 can be grounded (or connected to another reference voltage Vref) in any convenient manner, such as by using a wire, cable, or other electrical conductor. Any suitable conventional capacitor can be used as the second capacitor 50.

[0057] In a preferred embodiment, the first capacitor 42 is shaped to define a circular closed end 43, the cross-section of which may be semi-circular, and an annular wall portion 45 providing an opening. Specifically, the shapes of the first and second conductors 42A, 42B and the intermediate dielectric layer 42C define portions 43, 45 such that each portion 43, 45 includes a corresponding portion of conductors 42A, 42B and dielectric 42C. Preferably, the shape of the first capacitor 42 is such that at least a portion of the wall portion 45 is parallel or substantially parallel to the central axis of the capacitor 42, and is preferably cylindrical, particularly such that the inner surface of the wall portion adjacent to the opening is cylindrical. In a preferred embodiment, the transverse cross-section of the first capacitor 42 or at least the wall portion 45 is circular. Providing a dome-shaped capacitor 42 helps to eliminate or reduce edge effects, thereby improving the consistency of capacitor characteristics. Furthermore, the preferred dome design of the capacitor 42 makes the electric field between plates 42A, 42B symmetrical or substantially symmetrical, which is beneficial for accurate measurement. Additionally, the preferred shape of the capacitor 42 allows the capacitor 42 to have sufficient dielectric strength with minimal or relatively low capacitance.

[0058] Advantageously, the wall portion 45 of the first capacitor 42, typically the inner surface of the wall portion 45, is mechanically and electrically connected to the support 56, preferably to the free end 57. In a preferred embodiment, the first capacitor 42 covers the end 57 with an annular wall portion 45 extending around the end 57. Preferably, the respective inner surfaces of the wall portions 45 and the exterior of the end 57 are formed in a complementary manner, each preferably cylindrical, to facilitate engagement.

[0059] Optionally, the circuit breaker 10 includes a voltage sensor 60 for detecting the voltage at the second terminal 14. The voltage sensor 60 may include a voltage divider, preferably a capacitive voltage divider, having a voltage distribution with... Figure 3 The same or similar topological circuit structures are shown. Figure 1 A first capacitor 62, similar to the first capacitor 42 of the voltage sensor 40, is shown. A second capacitor for the voltage sensor is not shown, but can be positioned in any convenient location. The first capacitor 62 may be sleeve-shaped and located around the rod 14B, optionally inside the coil 36.

[0060] As will be apparent from the foregoing, a preferred embodiment of the invention is a built-in voltage sensor 40, including a capacitive voltage divider, located within the circuit breaker 10 or other switching device such as a recloser, between the first and second terminals 12, 14. The preferred voltage sensor 40 includes a U-shaped capacitor 42, which, as part of the voltage divider circuit, allows the use of a capacitor with sufficient dielectric strength and minimal necessary capacitance. Compared to conventional alternatives, this voltage sensor is relatively inexpensive and reliable, and has little or no impact on the size of the circuit breaker / recloser. The built-in voltage sensor 40 for terminal 12 is advantageous for use in ring networks where the sensor is required to be positioned at both terminals of the circuit breaker / recloser.

[0061] The present invention is not limited to the embodiments described herein, but can be modified or altered without departing from the scope of the present invention.

Claims

1. An electrical switching device, comprising: Electrically insulating outer casing; The first electrical terminal is connected to the first electrical contact; The second electrical terminal is connected to the second electrical contact; A means for actuating the second electrical contact between an open state and a closed state; and A voltage sensor is used to detect the voltage at the first electrical terminal. The voltage sensor includes a voltage divider having a voltage input connected to the first electrical terminal, a voltage output between the voltage input and a voltage reference, and a first capacitor connected between the voltage input and the voltage output. Furthermore, at least the first and second electrical contacts and the first capacitor of the voltage sensor are disposed within the housing, wherein the first capacitor is located between the first and second electrical terminals within the housing.

2. The switching device according to claim 1, wherein the electrically insulating housing comprises an electrically insulating molded part.

3. The switching device of claim 2, wherein the first electrical terminal includes a conductive member located within the housing and extending between the first electrical contact and the exposed first terminal connector, and the second electrical terminal includes a conductive member located within the housing and extending between the second electrical contact and the exposed second terminal connector, wherein the first capacitor is located between the conductive members, and wherein the conductive members of the first electrical terminal and the conductive members of the second electrical terminal are perpendicular to each other or substantially perpendicular to each other.

4. The switching device according to claim 3, wherein the first capacitor is located closer to the conductive member of the second electrical terminal than the conductive member of the first electrical terminal.

5. The switching device according to claim 3 or 4, further comprising at least one current sensing coil located around the conductive member of the second electrical terminal, the first capacitor being located adjacent to the at least one current sensing coil.

6. The switching device according to any one of claims 2 to 4, wherein the first capacitor is disposed on and electrically connected to the conductive support, the support is located inside the housing and electrically connected to a first electrical terminal, and wherein the first capacitor is disposed at an end of the support.

7. The switching device of claim 6, wherein the first electrical terminal includes a conductive member located within the housing and extending between the first electrical contact and the exposed first terminal connector, the support being mechanically connected to the conductive member or integrally formed with the conductive member to electrically connect the support and the conductive member to each other.

8. The switching device according to claim 6, wherein the first capacitor includes a first electrical conductor and a second electrical conductor, the first electrical conductor and the second electrical conductor being separated by a dielectric, wherein the first electrical conductor is electrically connected and mechanically connected to the support.

9. The switching device according to claim 1, wherein the first capacitor is dome-shaped.

10. The switching device according to claim 9, wherein the first capacitor includes an annular wall portion.

11. The switching device according to claim 6, wherein the first capacitor has a central axis and is symmetrical about the central axis.

12. The switching device according to claim 9, wherein the first capacitor has a central axis and is U-shaped in a cross-section taken parallel to the central axis.

13. The switching device of claim 10, wherein the first capacitor is disposed on and electrically connected to the conductive support, the support being located within the housing and electrically connected to a first electrical terminal, wherein the first capacitor is disposed at an end of the support, and wherein the annular wall portion is mechanically connected and electrically connected to the support.

14. The switching device according to claim 9, wherein the first capacitor is disposed on and electrically connected to the conductive support, the support being located within the housing and electrically connected to a first electrical terminal, and wherein the first capacitor is disposed at an end of the support, the first capacitor comprising a first electrical conductor and a second electrical conductor, wherein the first electrical conductor is electrically connected and mechanically connected to the support.

15. The switching device of claim 1, wherein the voltage divider is a capacitive voltage divider comprising a second capacitor connected between the voltage output and the voltage reference.

16. The switching device of claim 1, further comprising a low-potential structure having zero potential or substantially zero potential in use, wherein the first capacitor is located adjacent to the low-potential structure.

17. The switching device according to claim 16, wherein the low potential structure is disposed within the housing.

18. The switching device according to claim 16, wherein the low potential is carried by the second electrical terminal.

19. The switching device of claim 16, wherein the second electrical terminal includes a conductive member located within the housing and extending between the second electrical contact and the exposed second terminal connector, and wherein a low potential structure is carried by the conductive member.

20. The switching device according to claim 18 or 19, wherein the low potential structure includes an electrically insulating sleeve or coil located around the second electrical terminal.

21. The switching device of claim 20, wherein the low potential structure includes a coil of a current sensor.

22. The switching device according to claim 1, wherein at least the first capacitor is embedded or encapsulated within the electrically insulating housing.

23. The switching device according to claim 1, wherein the first electrical contact and the second electrical contact are part of a vacuum interrupter.

24. The switching device according to claim 1, wherein the switching device is a circuit breaker.

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