CN111989839A - Electric leakage detection device and electric leakage circuit breaker - Google Patents
Electric leakage detection device and electric leakage circuit breaker Download PDFInfo
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- CN111989839A CN111989839A CN201880092022.1A CN201880092022A CN111989839A CN 111989839 A CN111989839 A CN 111989839A CN 201880092022 A CN201880092022 A CN 201880092022A CN 111989839 A CN111989839 A CN 111989839A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
- H02H3/33—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors using summation current transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
- H02H3/34—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors of a three-phase system
- H02H3/347—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors of a three-phase system using summation current transformers
Abstract
The leakage detection device is provided with a zero-phase-sequence converter (10), a clamping circuit (20), a voltage conversion circuit (30), a low-pass filter (40), and a leakage determination circuit (50). The clamp circuit (20) limits the voltage (Vz) between secondary side terminals (13, 14) of the zero-phase-sequence current transformer (10) to be less than or equal to a clamp voltage. A voltage conversion circuit (30) is connected in parallel to the clamp circuit (20) and converts the output current (IZ) of the zero-phase-sequence converter (10) into a voltage (Vch). The electric leakage determination circuit (50) determines electric leakage of the circuit (2) based on the voltage (Vin) output from the low-pass filter (40). The voltage conversion circuit (30) has a series circuit of a voltage conversion element (31) for converting the output current (IZ) of the zero-phase-sequence converter (10) into a voltage (Vch), and an impedance adjustment element (32) for adjusting the impedance of the voltage conversion circuit (30).
Description
Technical Field
The present invention relates to an electric leakage detection device and an electric leakage breaker for determining electric leakage occurring in an electric circuit.
Background
In the past, an earth leakage breaker has: a zero-phase-sequence current transformer that detects a zero-phase current of the circuit; a voltage conversion circuit that converts a secondary-side current of the zero-phase-sequence converter into a voltage; a low-pass filter for removing a high-frequency component of the converted voltage; and a leakage determination circuit that determines leakage of the circuit based on the voltage output from the low-pass filter.
In such a leakage breaker, patent document 1 discloses a technique of providing a clamp circuit that limits a voltage between secondary side terminals of a zero-phase-sequence converter to a voltage equal to or lower than a clamp voltage so that a withstand voltage of an electronic component disposed on the secondary side of the zero-phase-sequence converter is not exceeded when an overcurrent is generated for a short period of time at a single time due to a lightning surge or the like.
Patent document 1: japanese patent laid-open publication No. 2006-148990
Disclosure of Invention
However, in the above-described conventional technique, since the clamp circuit and the low-pass filter are connected in parallel, the maximum value of the voltage input to the leakage determination circuit via the low-pass filter is defined by the clamp voltage of the clamp circuit. Since the clamp voltage is defined by the forward voltage of the diode constituting the clamp circuit, the clamp voltage cannot be lowered to a value smaller than the forward voltage of the diode. Therefore, even when a schottky barrier diode having a low forward voltage is used, it is difficult to set the maximum value of the voltage input to the leakage determination circuit to, for example, 100[ mV ]. As described above, in the conventional technology, the maximum value of the voltage input to the leakage determination circuit cannot be adjusted independently of the clamp voltage, and thus there is a problem that it is difficult to reduce the maximum value of the voltage input to the leakage determination circuit.
The present invention has been made in view of the above circumstances, and an object thereof is to obtain a leakage detection device capable of adjusting the maximum value of a voltage input to a leakage determination circuit independently of a clamp voltage.
In order to solve the above problems and achieve the object, a leakage detecting device according to the present invention includes a zero-phase-sequence converter, a clamp circuit, a voltage converting circuit, a low-pass filter, and a leakage determining circuit. The zero-phase-sequence current transformer detects a zero-phase current flowing in the circuit. The clamp circuit limits a voltage between secondary side terminals of the zero-phase-sequence current transformer to be less than or equal to a clamp voltage. The voltage conversion circuit is connected in parallel with the clamping circuit and converts the output current of the zero phase sequence converter into voltage. The low-pass filter removes high-frequency components of the voltage converted by the voltage converting circuit, and outputs the voltage from which the high-frequency components are removed. The leakage determination circuit determines the leakage of the circuit based on the voltage output from the low-pass filter. The voltage conversion circuit includes a series circuit of a voltage conversion element for converting an output current of the zero-phase-sequence converter into a voltage and outputting the converted voltage to the low-pass filter, and an impedance adjustment element for adjusting an impedance of the voltage conversion circuit.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, the maximum value of the voltage input to the leakage determination circuit can be adjusted independently of the clamp voltage.
Drawings
Fig. 1 is a diagram showing a configuration example of an earth leakage breaker according to embodiment 1 of the present invention.
Fig. 2 is a diagram showing an example of the relationship among the clamp voltage, the leakage determination threshold value, the voltage between the secondary-side terminals, and the voltage converted by the voltage conversion circuit according to embodiment 1.
Fig. 3 is a diagram for explaining the operation of the leakage detecting unit according to embodiment 1.
Fig. 4 is a diagram showing a configuration example of the earth leakage breaker according to embodiment 2 of the present invention.
Detailed Description
Next, an earth leakage detection device and an earth leakage breaker according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the present embodiment.
Embodiment 1.
Fig. 1 is a diagram showing a configuration example of an earth leakage breaker according to embodiment 1 of the present invention. As shown in fig. 1, the electrical leakage breaker 1 according to embodiment 1 includes: an opening/closing unit 3 that opens and closes the circuit 2; a leakage detection unit 4 that detects a leakage current flowing through the circuit 2; and a trip device 5 that controls the opening/closing unit 3 when the leakage is detected by the leakage detecting unit 4. The leakage detecting unit 4 is an example of a leakage detecting device.
The opening/closing section 3 has an opening/closing contact 3 for opening/closing the circuit 21、32. Each opening and closing contact 31、32The contact device includes a fixed contact not shown and a movable contact not shown. At the opening and closing contact 31The fixed contact and the movable contact are brought into contact, whereby the power source side connection terminal 61And a load side connection terminal 71Via a conductor 81And (6) electrically connecting. In addition, the opening/closing contact 32The fixed contact and the movable contact are brought into contact, whereby the power source side connection terminal 62And a load side connection terminal 72Via a conductor 82And (6) electrically connecting. As a result, a current flows through the circuit 2, and the earth leakage breaker 1 is turned on.
In addition, each opening/closing contact 31、32The fixed contact and the movable contact are separated, thereby the contact 3 is opened and closed1、32Is separated from the power source side connection terminal 61、62And a load side connection terminal 71、72Is electrically disconnected. Thereby, the current of the circuit 2 is interrupted and the earth leakage breaker 1 is in an off state. In the example shown in fig. 1, among the 3 phases of the R phase, S phase, and T phase of the circuit 2, those not shown areThe phase 1 is grounded, but any of the phases R, S and T may be ungrounded. In this case, 3 opening/closing contacts are provided in the opening/closing section 3.
The leakage detecting unit 4 includes a zero-phase-sequence converter 10, a clamp circuit 20, a voltage converting circuit 30, a low-pass filter 40, and a leakage determining circuit 50.
The zero-phase-sequence current transformer 10 detects a zero-phase current flowing in the circuit 2. The zero-phase-sequence converter 10 includes: a ring-shaped iron core 11 for the conductor 81、82Penetrating or winding; and a secondary winding 12 wound around the annular core 11. Secondary side terminals 13 and 14 are provided at both ends of the secondary winding 12, and a current Iz indicating a detection result of the zero-phase current detected by the zero-phase-sequence current transformer 10 is output from the secondary side terminals 13 and 14. Hereinafter, the current Iz may be referred to as an output current Iz.
The clamp circuit 20 is connected between the secondary side terminals 13 and 14 of the zero-phase-sequence current transformer 10, and sets a voltage Vz between the secondary side terminals 13 and 14 to be equal to or less than a clamp voltage Vclamp. In the example shown in fig. 1, the clamp circuit 20 has 2 diodes 21, 22 connected in anti-parallel. Thereby, the voltage Vz between the secondary side terminals 13, 14 is suppressed to be less than or equal to the forward voltage of the diodes 21, 22. As described above, the clamp circuit 20 operates with the forward voltages of the diodes 21 and 22 as the clamp voltage Vclamp.
The voltage conversion circuit 30 includes: a voltage conversion element 31 for converting the output current Iz of the zero-phase-sequence converter 10 into a voltage Vch; and an impedance adjusting element 32 that adjusts the impedance Z of the voltage conversion circuit 30. The voltage conversion element 31 and the impedance adjusting element 32 are connected in series. A series circuit of the voltage conversion element 31 and the impedance adjusting element 32 is connected in parallel to the clamp circuit 20. The voltage conversion circuit 30 will be described in detail later.
The low-pass filter 40 removes a high-frequency component of the voltage Vch output from the voltage conversion circuit 30. The high frequency component of the voltage Vch is a frequency component higher than the frequency of the leakage current detected by the leakage detecting unit 4. The cutoff frequency of the low-pass filter 40 is set to a frequency higher than the frequency of the leakage current so that the frequency component of the leakage current is not removed.
The electric leakage determination circuit 50 determines electric leakage of the circuit 2 based on the voltage Vin output from the low-pass filter 40. Specifically, the leakage determination circuit 50 compares the instantaneous value of the voltage Vin output from the low-pass filter 40 with the leakage determination threshold Vleak at a predetermined period T1. When the instantaneous value of the voltage Vin continuously exceeds the leakage determination threshold value Vleak for a predetermined period T2, the leakage determination circuit 50 determines that leakage has occurred in the circuit 2, and outputs a leakage detection signal Sleak at an effective level to the trip device 5. The period T1 is, for example, 1[ ms ], and the period T2 is, for example, 3[ ms ].
The leakage determination circuit 50 outputs an active-level leakage detection signal Sleak to the trip device 5 if it determines that leakage has occurred in the circuit 2. The active-level leakage detection signal Sleak is, for example, a High-level signal.
When the leakage detection signal Sleak of an active level is output from the leakage detection unit 4, the trip device 5 opens the circuit 2 and sets the electrical leakage breaker 1 in an open state by separating the fixed contacts and the movable contacts that are in a contact state in the opening/closing unit 3. The opening/closing unit 3 has an unillustrated opening/closing mechanism for moving the movable contact, and the trip device 5 is configured to act on the opening/closing mechanism to separate the fixed contact and the movable contact in a contact state.
When the instantaneous value of the voltage Vin is not equal to or greater than the leakage determination threshold value Vleak for a predetermined period T2, the leakage determination circuit 50 determines that no leakage has occurred in the circuit 2 and does not output the leakage detection signal Sleak at an effective level to the trip device 5. In this case, the fixed contacts and the movable contacts are still in a contact state in the opening/closing unit 3, and the electrical leakage breaker 1 maintains the on state.
Next, the voltage conversion circuit 30 will be described in more detail. In addition, for convenience of explanation, an overcurrent generated in a short period of time at a single time due to a lightning surge or the like will be referred to as a lightning surge current hereinafter. As described above, the voltage conversion circuit 30 includes the voltage conversion element 31 for converting the output current Iz of the zero-phase-sequence converter 10 into the voltage Vch, and the impedance adjustment element 32 for adjusting the impedance Z of the voltage conversion circuit 30.
As the impedance Z of the voltage conversion circuit 30 decreases, the voltage generated between the secondary side terminals 13 and 14 due to the lightning surge current decreases, and thus the ratio of the clamping by the clamping circuit 20 decreases. If the ratio of the clamping by the clamping circuit 20 is small, the possibility of malfunction of the earth leakage breaker 1 due to lightning surge current becomes high.
Therefore, in the earth leakage breaker 1, the impedance Z of the voltage conversion circuit 30 is adjusted by the impedance adjusting element 32 so that the voltage generated between the secondary side terminals 13, 14 due to the lightning surge current is clamped by the clamping circuit 20.
Here, the impedance Z of the voltage conversion circuit 30 and the clamp voltage Vclamp of the clamp circuit 20 will be specifically described. The voltage conversion element 31 of the voltage conversion circuit 30 is a resistor having a resistance Rf, and the impedance adjustment element 32 is a resistor having a resistance Radj.
When the clamp circuit 20 and the impedance adjusting element 32 are not provided in the leakage detecting unit 4, the voltage Vz between the secondary side terminals 13 and 14 is expressed by the following equation (1).
Vz＝Iz×Rf···(1)
In the case where the leakage detecting unit 4 does not include the clamp circuit 20 but includes the impedance adjusting element 32, the voltage Vz between the secondary side terminals 13 and 14 is expressed by the following equation (2).
Vz＝Iz×(Rf+Radj)···(2)
The impedance of the secondary winding 12 of the zero-phase-sequence current transformer 10 is small and negligible compared to the impedance Z of the voltage conversion circuit 30. Therefore, the magnitude of the output current Iz of the zero-phase-sequence converter 10 does not substantially change even if the magnitude of the impedance Z of the voltage conversion circuit 30 changes.
Therefore, by providing the impedance adjusting element 32 in the voltage conversion circuit 30, a voltage (Rf + Radj)/Rf times can be generated between the secondary side terminals 13 and 14, as compared with the case where the impedance adjusting element 32 is not provided. This can increase the ratio of the component clamped by the clamp circuit 20 among the components generated on the secondary side of the zero-phase-sequence current transformer 10 by the lightning surge current component.
The impedance Z of the voltage conversion circuit 30 is expressed by the following expression (3), and the voltage Vch output from the voltage conversion circuit 30 to the low-pass filter 40 is expressed by the following expression (4).
Z＝Rf+Radj···(3)
Vch＝Rf/(Rf+Radj)×Vz···(4)
Therefore, by appropriately adjusting the resistance values Radj of the impedance adjusting element 32 and the resistance value Rf of the voltage conversion element 31, the voltage Vch output from the voltage conversion circuit 30 can be adjusted to an arbitrary value smaller than the clamp voltage Vclamp of the clamp circuit 20. For example, by setting the voltage Vch output to the low-pass filter 40 to be 100[ mV ] or less, the voltage Vin input to the leakage determination circuit 50 can be set to be 100[ mV ] or less. As described above, the leakage detecting unit 4 can adjust the maximum value of the voltage Vin input to the leakage determining circuit 50 independently of the clamp voltage Vclamp.
Further, if the impedance Z of the voltage conversion circuit 30 is too large, the voltage Vz between the secondary side terminals 13 and 14 generated by the minimum value of the leakage current detected by the leakage detection unit 4 becomes larger than the clamp voltage Vclamp, and therefore, the leakage determination circuit 50 cannot determine the leakage. Therefore, the upper limit value of the impedance Z of the voltage conversion circuit 30 is a condition that the voltage Vz between the secondary- side terminals 13 and 14 generated by the minimum value of the leakage current detected by the leakage detection unit 4 is equal to or less than the voltage of the clamp voltage Vclamp.
Here, when the peak value of the output current Iz of the secondary side terminals 13 and 14 generated by the minimum leakage current detected by the leakage detecting unit 4 is Iz _ trip, the clamp voltage Vclamp satisfies the following expression (5). The minimum value of the leakage current is the lower limit value of the leakage current detected by the leakage detecting unit 4, and when the leakage current flowing through the circuit 2 is equal to or greater than the minimum value of the leakage current, the leakage is detected by the leakage detecting unit 4.
Vclamp≥Iz＿trip×(Rf+Radj)···(5)
The leakage determination threshold Vleak of the leakage determination circuit 50 satisfies the following expression (6).
Vleak＝Rf×Iz＿trip···(6)
Therefore, the resistance value Radj of the impedance adjusting element 32 can be expressed by the following formula (7).
Radj≤(Vclamp－Vleak)/Iz＿trip···(7)
The electric leakage determination circuit 50 detects electric leakage by whether or not the instantaneous value of the voltage Vin is greater than or equal to the electric leakage determination threshold Vleak, and therefore, is independent of the voltage to which the instantaneous value of the voltage Vin exceeds the electric leakage determination threshold Vleak. Therefore, the maximum value Radjmax of the resistance value Radj can be expressed by the following equation (8).
Radjmax＝(Vclamp－Vleak)/Iz＿trip···(8)
Here, Vclamp is 1[ V ], Vleak is 100[ mV ], and Iz _ trip is 200[ μ a ]. In this case, Radjmax is 4.5[ k Ω ] according to the above equation (8). Further, according to formula (6), Rf becomes 0.5[ k Ω ].
Fig. 2 is a diagram showing an example of the relationship among the clamp voltage, the leakage determination threshold value, the voltage between the secondary-side terminals, and the voltage converted by the voltage conversion circuit according to embodiment 1, and shows an example of a case where the leakage current determined by the leakage determination circuit 50 to have the minimum value of leakage flows in the circuit 2.
In the example shown in fig. 2, the peak value of the voltage Vz between the secondary side terminals 13, 14 is the same as the clamp voltage Vclamp. The peak value of the voltage Vch output from the voltage conversion circuit 30 is the same as the leakage determination threshold value Vleak. Since the cutoff frequency of the low-pass filter 40 is set higher than the frequency of the leakage current, the peak value of the voltage Vin output from the low-pass filter 40 is the same as the peak value of the voltage Vch output from the voltage conversion circuit 30.
Therefore, while the peak value of the voltage Vz between the secondary side terminals 13 and 14 is higher than the clamp voltage Vclamp, the peak value of the voltage Vin output from the low-pass filter 40 is the same as the leakage determination threshold value Vleak. Therefore, the period during which the peak value of the voltage Vz between the secondary side terminals 13 and 14 is determined to be higher than the clamp voltage Vclamp is equal to or longer than the period T2, and the leakage determination circuit 50 determines that leakage has occurred in the circuit 2.
Even when a lightning surge is applied to the circuit 2, the peak value of the voltage Vz between the secondary side terminals 13 and 14 is the same as the clamp voltage Vclamp, and the peak value of the voltage Vch output from the voltage conversion circuit 30 is the same as the leakage determination threshold value Vleak. The voltage Vch output from the voltage conversion circuit 30 is input to the low-pass filter 40.
The low pass filter 40 has a cut-off frequency lower than the frequency of the lightning surge current, and thus the voltage component involved in the lightning surge current is reduced by the low pass filter 40. Therefore, the peak value of the voltage Vin output from the low-pass filter 40 is lower than the peak value of the voltage Vch output from the voltage conversion circuit 30, and it is not determined by the leakage determination circuit 50 that leakage has occurred in the circuit 2. As described above, the leakage detecting unit 4 can increase the S/N Ratio (Signal-to-Noise Ratio) which is the Ratio of the voltage component generated by the lightning surge current to the voltage Vin.
Fig. 3 is a diagram for explaining the operation of the leakage detecting unit according to embodiment 1, and shows an example when a lightning surge is applied to the circuit 2 in which a leakage current of a magnitude determined as leakage by the leakage determining circuit 50 does not flow.
As shown in fig. 3, when a lightning surge current is applied to the circuit 2 through which a leakage current flows, a current obtained by superimposing the leakage current and a component of the lightning surge current flows through the circuit 2. At this time, the zero-phase-sequence converter 10 outputs an output current Iz having a waveform shown in fig. 3.
A voltage is generated across the voltage conversion circuit 30 due to the output current Iz of the zero-phase-sequence converter 10, and a voltage exceeding the clamping voltage Vclamp of the clamping circuit 20 is clamped by the clamping circuit 20. Therefore, the voltage Vz between the secondary side terminals 13 and 14 has a waveform shown in fig. 3.
The voltage conversion circuit 30 outputs a voltage Vch, which is a voltage of the voltage conversion element 31 generated by the output current Iz, to the low-pass filter 40. Since the low-pass filter 40 removes a high-frequency component from the voltage Vch output from the voltage conversion circuit 30, the voltage Vin having a waveform shown in fig. 3 is input from the low-pass filter 40 to the leakage determination circuit 50.
In the example shown in fig. 3, the voltage Vin output from the low-pass filter 40 is smaller than the leakage determination threshold Vleak, and therefore the leakage determination circuit 50 does not determine that there is leakage. As described above, when the lightning surge current is applied to the circuit 2, the leakage current determination circuit 50 does not determine that there is leakage and does not cause malfunction due to the lightning surge current of the circuit 2.
As described above, the leakage detecting unit 4 of the residual current circuit breaker 1 according to embodiment 1 includes the zero-phase-sequence converter 10, the clamp circuit 20, the voltage converting circuit 30, the low-pass filter 40, and the leakage determining circuit 50. The zero-phase-sequence current transformer 10 detects a zero-phase current flowing in the circuit 2. The clamp circuit 20 limits the voltage Vz between the secondary side terminals 13, 14 of the zero-phase-sequence current transformer 10 to be less than or equal to the clamp voltage Vclamp. The voltage conversion circuit 30 is connected in parallel to the clamp circuit 20, and converts the output current Iz of the zero-phase-sequence converter 10 into a voltage Vch. The low-pass filter 40 removes a high-frequency component of the voltage Vch converted by the voltage converting circuit 30, and outputs the voltage Vin obtained by removing the high-frequency component from the voltage Vch. The electric leakage determination circuit 50 determines electric leakage of the circuit 2 based on the voltage Vin output from the low-pass filter 40. The voltage conversion circuit 30 includes a series circuit of a voltage conversion element 31 for converting the output current Iz of the zero-phase-sequence converter 10 into a voltage Vch and outputting the converted voltage Vch to the low-pass filter 40, and an impedance adjustment element 32 for adjusting the impedance of the voltage conversion circuit 30.
Thus, the voltage Vin input to the leakage determination circuit 50 can be adjusted independently of the clamp voltage Vclamp of the clamp circuit 20. Therefore, for example, even when the leakage determination threshold value Vleak of the leakage determination circuit 50 is lower than the clamp voltage Vclamp, it is possible to avoid the leakage determination circuit 50 from malfunctioning due to a one-time overcurrent such as a lightning surge current. For example, when the diodes 21 and 22 of the clamp circuit 20 are normal diodes, the clamp voltage Vclamp is 0.7 to 1[ V ]. In addition, if the diodes 21 and 22 are schottky barrier diodes, the clamp voltage Vclamp is, for example, 0.3[ V ]. Therefore, it is difficult to set the clamp voltage Vclamp to 100[ mV ], and the voltage Vin input to the leakage determination circuit 50 due to the lightning surge current exceeds 100[ mV ] without the impedance adjusting element 32. At this time, if the leakage determination threshold Vleak of the leakage determination circuit 50 is 100 mV, the leakage determination circuit 50 erroneously detects the lightning surge current as a leakage current. On the other hand, since the leakage detecting unit 4 of the leakage breaker 1 according to embodiment 1 includes the impedance adjusting element 32, the maximum value of the voltage Vin input to the leakage determination circuit 50 can be easily adjusted in accordance with the leakage determination threshold Vleak of the leakage determination circuit 50 without adjusting the clamp voltage Vclamp itself. Therefore, even if the leakage determination threshold Vleak is, for example, 100 mV, the leakage detecting unit 4 can prevent erroneous detection.
In addition, the impedance adjusting element 32 includes a resistor. This allows the voltage Vch output from the voltage conversion circuit 30 to be adjusted independently of the frequency. Therefore, the voltage conversion circuit 30 can be adjusted regardless of the frequency.
In addition, when the instantaneous value of the voltage Vin output from the low-pass filter 40 is equal to or greater than the leakage determination threshold value Vleak for a predetermined period T2 or longer, the leakage determination circuit 50 determines that there is leakage in the circuit 2. Thus, for example, as compared with a case where the leakage of the circuit 2 is detected when the voltage Vin output from the low-pass filter 40 exceeds both the positive threshold value and the negative threshold value, the leakage occurring in the circuit 2 can be detected at a high speed.
Embodiment 2.
Although the impedance adjusting element is configured by a resistor in embodiment 1, embodiment 2 is different from embodiment 1 in that the impedance adjusting element is configured by an inductor. Hereinafter, the same reference numerals are used to designate the components having the same functions as those of embodiment 1, and the description thereof will be omitted, and the differences from the residual current circuit breaker 1 of embodiment 1 will be mainly described.
Fig. 4 is a diagram showing a configuration example of the earth leakage breaker according to embodiment 2 of the present invention. As shown in fig. 4, the earth leakage breaker 1A according to embodiment 2 includes an opening/closing unit 3, an earth leakage detecting unit 4A, and a trip device 5. The leakage detecting unit 4A includes a zero-phase-sequence converter 10, a clamp circuit 20, a voltage converting circuit 30A, a low-pass filter 40, and a leakage determining circuit 50.
The voltage conversion circuit 30A includes a voltage conversion element 31 and an impedance adjustment element 32A. The voltage conversion element 31 is a resistor having a resistance Rf, and the impedance adjustment element 32A is an inductor having an inductance L.
The impedance Z of the voltage conversion circuit 30A is expressed by the following expression (10), and the voltage Vch output from the voltage conversion circuit 30A is expressed by the following expression (11) で.
Z＝√{Rf2+(ωL)2}···(10)
Vch＝Rf/√{Rf2+(ωL)2}×Vz···(11)
Therefore, by appropriately adjusting the inductance value L of the impedance adjusting element 32A and the resistance value Rf of the voltage conversion element 31, the voltage Vch output from the voltage conversion circuit 30A can be adjusted to an arbitrary value smaller than the clamp voltage Vclamp of the clamp circuit 20. For example, the voltage Vin input to the leakage determination circuit 50 may be set to a small value of 100mV or less.
When the peak value of the output current Iz of the secondary- side terminals 13 and 14, which is generated by the minimum leakage current detected by the leakage detecting unit 4A, is Iz _ trip, the clamp voltage Vclamp satisfies the following expression (12).
Vclamp≥Iz＿trip×√{Rf2+(ωL)2}···(12)
The leakage determination threshold Vleak of the leakage determination circuit 50 satisfies the following expression (13).
Vleak≥Rf×Iz＿trip···(13)
Therefore, the inductance value L of the impedance adjusting element 32A is expressed by the following formula (14).
L≤√(Vclamp2/Iz＿trip2－Rf2)/ω···(14)
The electric leakage determination circuit 50 detects electric leakage by whether or not the instantaneous value of the voltage Vin is greater than or equal to the electric leakage determination threshold Vleak, and therefore the value of the voltage exceeding the electric leakage determination threshold Vleak is not used for processing. Therefore, the maximum value Lmax of the inductance value L is expressed by the following formula (15).
Lmax＝√(Vclamp2/Iz＿trip2－Rf2)/ω···(15)
Here, Vclamp 1[ V ], Iz _ trip 200[ μ a ], ω 2 pi f, f 50[ Hz ], and Rf 500[ Ω ]. In this case, according to the above formula (15), Lmax is 15.8[ H ].
Since the frequency of the lightning surge current is higher than the frequency of the leakage current, "ω" in the above equation (15) can be set to a frequency higher than the frequency of the leakage current. For example, when the frequency of the lightning surge current is known, "ω" in the above equation (15) can be set as the frequency of the lightning surge current. For example, when the frequency of the lightning surge current is 100[ kHz ], by setting ω to 100[ kHz ] in the above equation (15), Lmax to 7.9[ mH ] can be set. Thus, for example, the voltage Vin input to the leakage determination circuit 50 can be limited in a frequency band of a high-frequency component of the output current Iz and a frequency band lower than the cutoff frequency of the low-pass filter 40.
In the leakage detecting unit 4A of the leakage breaker 1A according to embodiment 2, the impedance adjusting element 32A includes an inductor. Thus, the impedance of the impedance adjusting element 32A in the case where the lightning surge current flows in the circuit 2 is larger than the impedance of the impedance adjusting element 32A in the case where the leakage current flows in the circuit 2. Therefore, even when the lightning surge current flows through the circuit 2, the voltage Vin input to the electrical leakage determination circuit 50 can be significantly reduced as compared to the electrical leakage determination threshold value Vleak, and erroneous detection in the electrical leakage determination circuit 50 can be suppressed with high accuracy.
In the impedance adjusting elements 32 and 32A according to embodiments 1 and 2, the capacitance elements may be connected in parallel or in series. Thus, when a current having a high frequency such as a lightning surge current flows through the circuit 2, the voltage Vin input to the leakage determination circuit 50 can be made smaller than when a leakage current flows through the circuit 2. Further, although the voltage conversion element 31 of embodiment 1 is constituted by a resistor, the voltage conversion element 31 may be constituted by an element in which a resistor and an inductor are connected in series. The adjustment of the impedance adjusting elements 32 and 32A is an example, and the adjustment of the impedance adjusting elements 32 and 32A is not limited to the above example.
The configuration described in the above embodiment is an example of the content of the present invention, and may be combined with other known techniques, and a part of the configuration may be omitted or modified without departing from the scope of the present invention. The leakage detecting units 4 and 4A can be applied to apparatuses or devices other than the leakage breakers 1 and 1A. For example, the leakage detecting units 4 and 4A can be applied to a leakage monitoring device, a leakage relay, another measuring device, and the like.
Description of the reference numerals
1. The circuit breaker comprises a 1A leakage circuit breaker, a 2 circuit, a 3 switching part, 31, 32 switching contacts, 4A leakage detection parts, a 5 trip device, 61, 62 power supply side connecting terminals, 71, 72 load side connecting terminals, 81, 82 conductors, a 10 zero phase sequence current transformer, an 11 annular iron core, a 12 secondary winding, 13, 14 secondary side terminals, a 20 clamping circuit, 21, 22 diodes, a 30, 30A voltage conversion circuit, a 31 voltage conversion element, 32A impedance adjustment elements, a 40 low-pass filter, a 50 leakage judgment circuit, an Iz output current, Vch, Vin, Vz voltage, a Vleak leakage judgment threshold value and a T2 period.
Claims (5)
1. An electric leakage detection device is characterized by comprising:
a zero-phase-sequence current transformer that detects a zero-phase current flowing in the circuit;
a clamp circuit that limits a voltage between secondary-side terminals of the zero-phase-sequence current transformer to be less than or equal to a clamp voltage;
a voltage conversion circuit connected in parallel to the clamp circuit and converting an output current of the zero phase-sequence converter into a voltage;
a low-pass filter that removes a high-frequency component of the voltage converted by the voltage conversion circuit and outputs the voltage from which the high-frequency component is removed; and
An electric leakage determination circuit that determines electric leakage of the circuit based on the voltage output from the low-pass filter,
the voltage conversion circuit includes a series circuit of a voltage conversion element that converts the output current of the zero-phase-sequence converter into the voltage and outputs the converted voltage to the low-pass filter, and an impedance adjustment element that adjusts the impedance of the voltage conversion circuit.
2. An electric leakage detection apparatus according to claim 1,
the impedance adjustment element includes a resistor.
3. An electric leakage detection apparatus according to claim 1,
the impedance adjustment element includes an inductance.
4. A leakage detecting device according to any of claims 1 to 3,
the leakage determination circuit determines that there is leakage in the circuit when a state in which the instantaneous value of the voltage output from the low-pass filter is greater than or equal to a threshold value continues for a period greater than or equal to a predetermined period.
5. An earth leakage circuit breaker, comprising:
the electrical leakage detection device according to any one of claims 1 to 4;
an opening/closing unit that opens and closes the circuit; and
And a trip device that causes the opening/closing unit to open the circuit when the electric leakage determination circuit determines that the electric leakage is present in the circuit.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP2018/014691 WO2019193743A1 (en) | 2018-04-06 | 2018-04-06 | Electric leak detection device and electric leak circuit breaker |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111989839A true CN111989839A (en) | 2020-11-24 |
| CN111989839B CN111989839B (en) | 2022-12-06 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201880092022.1A Active CN111989839B (en) | 2018-04-06 | 2018-04-06 | Electric leakage detection device and electric leakage circuit breaker |
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| Country | Link |
|---|---|
| JP (1) | JP6896158B2 (en) |
| KR (1) | KR20200125671A (en) |
| CN (1) | CN111989839B (en) |
| TW (1) | TWI679434B (en) |
| WO (1) | WO2019193743A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114475255A (en) * | 2022-02-23 | 2022-05-13 | 中车青岛四方车辆研究所有限公司 | High-voltage on-load self-checking method and system for traction converter of railway vehicle |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102465612B1 (en) * | 2021-09-10 | 2022-11-11 | 태성전기산업주식회사 | Themal circuit breaker for instantaneous interruption and distribution board including it |
| WO2023176039A1 (en) * | 2022-03-17 | 2023-09-21 | 三菱電機株式会社 | Equipment diagnostic device and equipment diagnostic system |
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- 2018-04-06 WO PCT/JP2018/014691 patent/WO2019193743A1/en active Application Filing
- 2018-04-06 JP JP2020511569A patent/JP6896158B2/en active Active
- 2018-04-06 CN CN201880092022.1A patent/CN111989839B/en active Active
- 2018-04-06 KR KR1020207027738A patent/KR20200125671A/en active IP Right Grant
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Also Published As
| Publication number | Publication date |
|---|---|
| JPWO2019193743A1 (en) | 2020-10-08 |
| TW201944084A (en) | 2019-11-16 |
| CN111989839B (en) | 2022-12-06 |
| WO2019193743A1 (en) | 2019-10-10 |
| JP6896158B2 (en) | 2021-06-30 |
| KR20200125671A (en) | 2020-11-04 |
| TWI679434B (en) | 2019-12-11 |
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