JP5615958B1 - Earth leakage breaker - Google Patents

Abstract

The present invention provides an earth leakage circuit breaker that can easily and reliably determine whether a leakage current of a monitoring target circuit or a non-monitoring target circuit. The present invention relates to an earth leakage breaker 1 used in a facility configuration in which a plurality of transformers share a class B grounding wire 5 with an external zero-phase current transformer ZCT2 on the class B grounding wire 5. A detection circuit 6 is configured by connecting a secondary side of the internal zero-phase current transformer ZCT1 provided in the earth leakage circuit breaker 1 and a secondary side of the external zero-phase current transformer ZCT2 in series; Based on the secondary current flowing through the detection circuit 6 and the parameter based on the secondary side voltage of the internal zero-phase current transformer ZCT1, it is determined whether the leakage is a leakage of the monitoring target circuit or a non-monitoring leakage. [Selection] Figure 1

Description

  The present invention relates to an earth leakage circuit breaker that automatically shuts off when a zero-phase current exceeds a certain level.

  The general earth leakage breaker used in the low-voltage circuit is a system that automatically shuts off when the current flowing through the zero-phase current transformer built in the earth leakage breaker exceeds a certain level. For earth leakage circuit breakers used in important circuits, the zero-phase voltage and zero-phase current are taken into the circuit breaker control device so that they operate only when an accident occurs in the circuit breaker circuit. There are also facilities.

  When multiple transformers for in-station power supply or single-phase three-wire transformers are used in combination, Class B grounding is shared, so if a leakage occurs in the circuit to be protected by the leakage breaker, etc. There is a case in which a leakage current flows through the zero-phase current transformer of the earth leakage breaker (a ugly current), which causes an inconvenience that an unnecessary power failure of a normal circuit occurs. In addition, when a plurality of earth leakage breakers are simultaneously operated by a large current, there is a problem that it is difficult to identify a leakage point (leakage circuit).

  Therefore, in order to prevent the above-described malfunction of the earth leakage circuit breaker, conventionally, as disclosed in Patent Document 1 (Japanese translations of PCT publication No. 2008-546149), the total earth leakage detected by the zero-phase current transformer is known. The power supply from the power supply is automatically cut off by judging the leakage current from the total leakage voltage of the current, and the presence or absence of leakage is judged by the pure leakage voltage of the pure leakage current synchronously detected by the synchronous detector. There has been proposed a double shutoff method that automatically shuts off the power supply from the power supply.

  Moreover, as shown in Patent Document 2 (Japanese Patent Application Laid-Open No. 2011-249042), the transformer B type grounding phase and the D type or C type grounding pole of the non-monitoring circuit causing the scooping operation or the electricity connected thereto The circuit-to-ground voltage generated between the equipment grounding structure and the like is monitored, and the phase of the leakage current detected by the zero-phase current transformer is determined based on this voltage, and the leakage current is detected. If the current is from the load side of the transformer to the power supply side, that is, from the transformer side, and if the voltage between the circuit and the ground exceeds the set value of the operating sensitivity voltage, the leakage detection device There has also been proposed a configuration in which an unnecessary operation due to a large current is prevented without impeding the high-sensitivity operation region of the leakage detection device by adding an output control circuit for stopping the output operation.

JP 2008-546149 A JP 2011-249042 A

  However, in Patent Document 1, in order to detect a pure earth leakage voltage using a synchronous detector, it is necessary to provide a voltage divider that divides and detects the voltage in the electric circuit, and when a malfunction occurs in this voltage divider, the earth leakage occurs. There is a problem that this possibility arises.

  Moreover, in patent document 2, in addition to the leakage current from a conventional zero-phase current transformer, a transformer type B ground phase and a type D or type C ground electrode (or a grounding structure of an electrical facility connected to this) And the phase of the leakage current detected by the zero-phase current transformer is determined based on this voltage, and the leakage current is a large current. When the inter-voltage is greater than or equal to a predetermined value, it is necessary to add an output control circuit that stops the output of the leakage detection device.

  As mentioned above, in cases where multiple transformers for on-site power supply or single-phase three-wire transformers are used in combination, Class B grounding is shared. If this occurs, the leakage current also flows through the zero-phase current transformers of other earth leakage breakers, and there is a disadvantage that unnecessary power outages occur in a plurality of normal circuits. In the technical literature, the voltage between the electric circuits is monitored, or the voltage generated between the B-type ground and the other ground electrode is monitored, and there is a problem that the structure and processing are complicated. .

  In view of this, the present inventor noticed that a current flows in a class B grounding wire that is shared when a leak occurs in a certain circuit, and attached a current transformer to the class B grounding wire. Is connected to the zero-phase current detection current transformer in series (same polarity), and the leakage current of the monitoring circuit for the leakage breaker is determined from the secondary current of the zero-phase current transformer and the voltage of the leakage breaker current transformer. It was verified whether it was possible to determine whether the accident occurred in another circuit.

  As shown in FIG. 9A, a zero-phase current transformer verification circuit that assumes a case where a circuit to be monitored has a leakage current is a closed circuit (primary circuit) C1 that assumes a leakage current to which a constant power supply Vc is connected. Formed as. The closed circuit C1 includes a first zero-phase current transformer ZCT1 provided on the line L1 imitating the electric circuit and a second zero-phase current transformer ZCT2 provided on the line L2 imitating the type B ground line. Each of the secondary sides is connected in series to form a closed circuit (secondary circuit) C2 together with the resistor R. In a measuring instrument (not shown), the current I1 flowing through the circuit C1 is detected by the channel CH1, the voltage Vr generated in the resistor R is detected by the channel CH2, and the first zero-phase current transformer secondary voltage Vzct1 is detected by the channel CH3. The second zero-phase current transformer secondary side voltage Vzct2 is detected by the channel CH4. The resistor R is a current resistor that generates a voltage of 100 mV when a current of 0.1 A is passed through the primary circuit C1. The detection result by each channel is shown in FIG.

  With the above configuration, when the current I1 (= I2) flows (leakage) in the primary circuit C1, the current flowing in the first zero-phase current transformer ZCT1 and the current flowing in the second zero-phase current transformer ZCT2 are Since the direction is the same, the first zero-phase current transformer secondary side voltage Vzct1 and the second zero-phase current transformer secondary side voltage Vzct2 were verified to be substantially zero. As a result, it is possible to determine that this is an internal accident (monitored circuit fault).

  As shown in FIG. 10A, the zero-phase current transformer verification circuit that assumes a case where a circuit not to be monitored has a leak is a closed circuit (primary circuit) that assumes a leak to which a constant power supply Vc is connected. Formed as C1. In this case, the first zero-phase current transformer ZCT1 constituting the secondary circuit C2 is arranged in the circuit L3 where no leakage current flows. Thus, when a circuit that is not monitored is leaked, the current I1 flowing through the first zero-phase current transformer ZCT1 is zero, and the current I2 flowing through the second zero-phase current transformer ZCT2 is a predetermined value ( In this embodiment, 0.1A). As a result, when the detection result by each channel is seen, as shown in FIG. 10B, the voltage Vzct1 generated in the first zero-phase current transformer ZCT1 indicated by CH3 has a negative polarity. When Vzct1 has a negative polarity, it is possible to determine that the accident is an external accident (a circuit fault that is not monitored).

  Furthermore, in another zero-phase current transformer verification circuit that assumes a case in which a circuit to be monitored is leaked, current flows through a route L4 different from the B-type ground line L2, as shown in FIG. In this case, in particular, the circuit assumes a case of a leakage accident in which 50% of the leakage current does not pass through the second zero-phase current transformer ZCT2. In this circuit, I1 = I2 + I3.

  When the detection result by each channel in this case is seen, the voltage Vzct1 generated in the first zero-phase current transformer ZCT1 indicated by CH3 is positive as shown in FIG. It is possible to determine that this is a (monitored circuit fault).

  From the above verification results, the present invention is provided with a zero-phase current transformer on the shared class B ground wire, and the secondary side of this zero-phase current transformer and the secondary phase current transformer secondary side inside the earth leakage breaker Are connected in series, and the leakage current of the monitoring target circuit or the leakage current of the non-monitoring target circuit is determined from the zero-phase current transformer secondary current (zero-phase current) flowing in this way and the voltage of the current breaker current transformer. The main issue is to provide an earth leakage circuit breaker.

  In order to achieve the above-mentioned problem, the present invention provides an earth leakage breaker used in an equipment configuration in which a plurality of transformers share a B-type ground line, and the B-type ground line has an external zero-phase current transformer. The detection circuit is configured by connecting the secondary side of the internal zero-phase current transformer provided in the earth leakage breaker and the secondary side of the external zero-phase current transformer in series, and the detection Zero-phase current detection means for detecting current flowing in the circuit, secondary-side voltage detection means for detecting the secondary-side voltage of the internal zero-phase current transformer, and zero-phase current detected by the zero-phase current detection means When the parameter based on the secondary side voltage of the internal zero-phase current transformer detected by the secondary side voltage detecting means is within a predetermined range around zero, The secondary side voltage of the internal zero-phase current transformer detected by the secondary side voltage detection means An earth leakage processing means for judging that the circuit to be monitored of the earth leakage circuit breaker is an earth leakage when the parameter based on the second predetermined value is larger than a predetermined range around zero, and the zero phase When the zero-phase current detected by the current detection means is greater than or equal to the first predetermined value, the parameter based on the secondary-side voltage of the internal zero-phase current transformer detected by the secondary-side voltage detection means is around zero And an interruption preventing means for invalidating the interruption of the circuit by determining that the electric leakage of the circuit outside the monitoring target of the electric leakage breaker is an electric leakage when the electric leakage is not within the predetermined range and not more than the second predetermined value. Like to do.

  As described above, when the zero-phase current is equal to or greater than the predetermined value, it is determined that a leakage current has occurred in the monitoring target circuit or the non-monitoring target circuit. Here, when the parameter based on the secondary side voltage of the internal zero-phase current transformer is zero or within a predetermined range around zero, as can be seen from the verification result of the verification circuit shown in FIG. It can be determined that there is a leak. When the parameter based on the secondary side voltage is equal to or greater than a predetermined value, it can be determined that the monitoring target circuit is leaked, as can be seen from the verification result of the verification circuit shown in FIG. However, when the parameter based on the secondary side voltage is not within the predetermined range around zero and not more than the second predetermined value, in other words, when it is negative, and the second predetermined value is larger than the predetermined range. In the case of a positive value smaller than that, it can be determined that the leakage of the circuit not to be monitored is a leakage, and the interruption of the leakage breaker can be invalidated. For this reason, it becomes possible to interrupt | block only the earth-leakage circuit breaker in which the earth leakage occurred.

  Further, the parameter based on the secondary side voltage may be an integral value of the secondary side voltage within a predetermined time from the time when the polarity of the zero phase current detected by the zero phase current detecting means is reversed from minus to plus, or the zero phase It is desirable that the average value of the secondary side voltage within a predetermined time from the time when the polarity of the zero-phase current detected by the current detecting means is reversed from minus to plus. The average value is preferably calculated from the integral value, and the effective value may be calculated instead of the average value.

  As a result, it is possible to reliably detect whether the polarity of the secondary voltage is positive or negative with respect to the polarity of the zero-phase current, so that the above-described operation can be performed reliably. Furthermore, this makes it possible to prevent a transient phenomenon in which the voltage / current generated at the moment of the leakage accident changes suddenly, a malfunction due to a minute current caused by voltage imbalance, a malfunction due to noise, or the like.

  Furthermore, the predetermined time is preferably 4 ms. This is within the theoretical time when positive voltage is generated when leakage occurs in the monitored circuit (approx. 4.17 ms for 60 Hz and 5 ms for 50 Hz, so 4 ms satisfying both is adopted) It is possible to prevent malfunctions by integrating a voltage obtained by integrating the voltage or calculating an average value or an effective value by integration and comparing with a predetermined value.

  The detection circuit is preferably provided with a voltage suppression element so that the voltage does not exceed a predetermined value. As a result, it is possible to protect the control circuit, particularly the electronic component, from an abnormal voltage generated in the detection circuit due to an accident.

According to the earth leakage breaker of the present invention,
1. Even if it is an equipment configuration that shares Class B grounding with multiple transformers, a healthy circuit will not cause an unnecessary power failure due to a leakage accident outside the circuit to be protected (equipment reliability will be improved),
2. Since it is possible to prevent the operation of multiple earth leakage breakers with a single earth leakage accident, it is easy to identify the location of the earth leakage accident, and quick recovery from the accident.
3. Since it is not necessary to capture the zero-phase voltage, protection is possible at a low cost.
4). Since there is no need to increase the operation set value to avoid unnecessary operation of the earth leakage breaker, the risk of electric shock can be eliminated.
5. Since it is only necessary to attach a current transformer to the class B grounding wire, there are various effects such as installation of a leakage breaker without modifying or changing the existing electrical equipment.

It is a schematic block diagram of the earth-leakage circuit breaker which concerns on this invention. It is a flowchart figure of the control performed with the earth-leakage circuit breaker which concerns on this invention. It is explanatory drawing which shows the state which attached the earth-leakage circuit breaker which concerns on this invention to a single phase transformer. It is explanatory drawing which shows the state which attached the earth-leakage circuit breaker which concerns on this invention to a three-phase transformer. In the three-phase transformer shown in FIG. 4, it is explanatory drawing which shows the state of the 1st earth-leakage accident in a monitoring object circuit. In the three-phase transformer shown in FIG. 4, it is explanatory drawing which shows the state of the 2nd earth-leakage accident in a monitoring object circuit. It is explanatory drawing which shows the waveform of each parameter of the detection circuit when the 1st electric leakage accident shown in FIG. 5 occurs. It is explanatory drawing which shows the waveform of each parameter of the detection circuit at the time of the 2nd electric leakage accident shown in FIG. FIG. 9A is a zero-phase current transformer verification circuit that assumes a case where a circuit to be monitored is leaked, and FIG. 9B is a detection result of each parameter. FIG. 10A is a zero-phase current transformer verification circuit that assumes a case where a circuit that is not monitored is leaked, and FIG. 10B is a detection result of each parameter. FIG. 11A shows another zero-phase current transformer verification circuit that assumes a case where a circuit to be monitored is leaked. FIG. 11B shows detection results of each parameter.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the earth leakage circuit breaker 1 according to the present invention includes a pair of wirings 3 and 4 connected to a circuit to be protected, and a wiring breaker that opens and closes the wirings 3 and 4 according to an interruption command from the control circuit 2. A capacitor CB, an internal zero-phase current transformer ZCT1 provided in the wirings 3 and 4, and a secondary side connected in series (with the same polarity) to the secondary side of the internal zero-phase current transformer ZCT1, It is comprised by the external zero phase current transformer ZCT2 provided in the common B class grounding wire 5. FIG.

  The control circuit 2 includes a detection circuit 6 in which the secondary side of the internal zero-phase current transformer ZCT1 and the secondary side of the external zero-phase current transformer ZCT2 are connected in series. The A / D converter 21 that converts the flowing zero-phase current Io and the secondary side voltage Vzct1 of the internal zero-phase current transformer ZCT1 into a digital signal, and processes the signal based on the signal from the A / D converter 21. Microprocessor (MPU) 22, memory (Me) 23 for storing calculation results and processing programs of the microprocessor 22, and input / output port for transmitting a shut-off command to the circuit breaker CB according to a command from the microprocessor 22 (I / O) 24 at least. Furthermore, the detection circuit 6 is preferably provided with a voltage suppression element (not shown) made of a non-linear element such as a varistor in order to protect the electronic component from an abnormal voltage.

In FIG. 2, an example of a control operation executed by the microprocessor 22 of the control device 2 is shown as a flowchart.
In this control started from step 100, it is determined in step 110 whether or not the zero-phase current Io is equal to or greater than a predetermined value α (100 mA in this embodiment). In this determination, if the zero-phase current Io is equal to or greater than the predetermined value α, it is known that a leakage has occurred in the monitoring target circuit or the non-monitoring target circuit. When the zero-phase current Io is smaller than the predetermined value α, it is determined that there is no leakage, and thus the monitoring of the zero-phase current Io is continued.

  In step 120, the secondary-side voltage Vzct1 of the internal zero-phase current transformer ZCT1 is integrated for a predetermined time (4 ms) from the time when the zero-phase current Io is inverted from the negative electrode (minus) to the positive electrode (plus), and the integration result is obtained. From this, the average voltage Vave is calculated.

  In step 130, it is determined whether or not the average voltage Vave is within a predetermined range around zero (−β ≦ Vave ≦ + β). In this example, β is 0.1V. Thus, when the average voltage of the secondary-side voltage Vzct1 of the internal zero-phase current transformer ZCT1 is approximately 0 V, it can be determined that the monitoring target circuit is leaking. Then, the circuit breaker CB for wiring is opened to complete the disconnection of the wirings 3 and 4, and the control is completed in step 170.

  If it is determined in step 130 that the average voltage Vave is not within the range of ± β (± 0.1 V), the routine proceeds to step 140 where γ (this embodiment) where the average voltage Vave is larger than β. Then, it is determined whether or not it is 0.2V or more. In this determination, if the average voltage Vave is greater than or equal to the predetermined value γ, it is determined that the monitoring target circuit is leaking, as is clear from the verification shown in FIG. , 4 are automatically shut off.

  If it is determined in step 150 that the average voltage Vave is smaller than the predetermined value γ, whether the average voltage Vave is a value (negative electrode) smaller than −β, or is not less than + β and not more than + γ. It can be seen that it is. In particular, when the average voltage Vave is a negative electrode, it is clear from the verification shown in FIG. 10 that the leakage of the circuit not to be monitored is detected. . If the average voltage Vave is larger than + β and smaller than + γ, it is determined that the leakage target is in the range of the leakage fault that is a leakage current of the monitored circuit but does not cut off the accident. Proceed with blocking.

  FIG. 3 shows equipment having a single-phase transformer configuration equipped with the earth leakage circuit breaker 1 according to the present invention. In this facility, the wires 3A and 4A of the earth leakage breaker 1A are connected to the 210V bus connected to the two single-phase transformers 10 and 11, and the wires 3B and 3C of the earth leakage breaker 1B are two single-phases. Connected to 105 / 210V single-phase three-wire electric wire connected to transformers 10 and 11, external zero-phase current transformers ZCT2-2 and ZCT1-2 of each earth leakage breaker 1A and 1B are single-phase transformers. It is arranged on the common type B ground line 5 of the containers 10 and 11.

  FIG. 4 shows the equipment of the three-phase transformer configuration equipped with the earth leakage circuit breaker 1 according to the present invention. In this facility, the wires 3C and 4C of the earth leakage breaker 1C are connected to the 210V bus connected to the three-phase transformer 12, and the wires 3D and 4D of the earth leakage breaker 1D are connected to the three-phase transformer 12. The external zero-phase current transformers ZCT2-2 and ZCT1-2 of the respective earth leakage circuit breakers 1C and 1D are arranged on the common type B ground line 5 of the three-phase transformer 12.

  FIG. 5 shows an example of when a leakage occurs in the equipment having the three-phase transformer configuration shown in FIG. In this three-phase transformer configuration, when a leakage occurs in the 200V circuit (grounded by the ground fault resistance Rg), the line 3C of the leakage breaker (200V_ELB) 1C on the 200V side is connected via the resistor Rg. The ground fault current Io flows through the B-type grounding wire 5, and an electromotive force is generated in the internal zero-phase current transformer ZCT2-1 on the 200V side in the V2-1 direction, and the external zero-phase current transformer ZCT2-2. In this case, an electromotive force is generated in the V2-2 direction. In this case, since the direction of the electromotive force is the same direction, the detection circuit 6C of the 200V side earth leakage circuit breaker 1C has a low impedance circuit configuration, so the secondary voltage V2- of the internal zero-phase current transformer ZCT2-1. 1 becomes almost zero, and io2 flows through the detection circuit 6C in the direction of the arrow in the figure. As described above, the integration amount of the secondary voltage V2-1 during the predetermined time ti (4 ms in the present embodiment) from the time when the polarity of io2 changes from the negative pole to the positive pole (the integrated value of the predetermined time ti or there) As shown in FIG. 7A, the average value and the effective value calculated from the above are almost zero, and the average voltage Vave is also zero.

  On the other hand, in the earth leakage breaker (100V_ELB) 1D on the 100V side, since the current Io flows through the external zero-phase current transformer ZCT1-2, the external zero-phase current transformer ZCT1-2 starts in the V1-2 direction. Although electric power is generated, Io does not flow through the internal zero-phase current transformer ZCT1-1. Therefore, no electromotive force is generated in the internal zero-phase current transformer ZCT1-1, and a high impedance state is obtained. The electromotive force generated by the zero-phase current transformer ZCT1-2 causes the internal zero-phase current transformer ZCT1-1 to generate a voltage in the direction of the voltage V1-1. For this reason, the current io1 flows in the detection circuit 6D in the direction of the arrow in the figure. Here, looking at the relationship between the current io1 and the voltage V1-1, unlike the detection circuit 6C on the 200V side, the internal zero-phase current transition within a predetermined time ti from the time when the polarity of the current io1 changes from the negative pole to the positive pole. When looking at the integrated value of the voltage V1-1 of the device ZCT1-1 and the average voltage Vave (or effective value) calculated therefrom, as shown in FIG. It turns out that it is an accident (external accident).

  Thus, in the example shown in FIG.5 and FIG.7, 200V side earth leakage breaker (200V_ELB) 1C is an accident (internal accident) of a monitoring object circuit, and with respect to this earth leakage accident of 200V side earth leakage breaker 1C The 100V side earth leakage breaker (100V_ELB) 1D can be determined to be an accident (external accident) of a circuit that is not monitored.

  7A and 7B, the zero-phase currents flowing in the primary side of the internal zero-phase current transformer ZCT2-1 and the external zero-phase current transformer ZCT2-2 in the 200V side detection circuit 6C are values in the same direction. Therefore, the voltage generated on the secondary side of each zero-phase current transformer is zero. Furthermore, in the 100V side detection circuit 6D, the zero-phase current Io flows through the external zero-phase current transformer ZCT1-2, but does not flow through the internal zero-phase current transformer ZCT1-1. The voltage V1-1 is generated in the internal zero-phase current transformer ZCT1-1. The voltage ZCT1-1 and the voltage V1-2 generated in the external zero-phase current transformer ZCT1-2 have opposite polarities as shown in FIG.

  In the above, the case where the leakage accident has occurred in the 200V circuit has been described. However, the same action also works when the leakage accident has occurred in the 100V circuit, and an internal accident is determined in the 100V circuit and an external accident is determined in the 200V circuit. .

  FIG. 6 shows a case where, in a three-phase transformer configuration, a leakage occurs in the 200V circuit (grounded by the ground fault resistance Rg), and a part of the zero-phase current flows to another circuit. In this case, in the detection circuit 6C on the 200V side, a difference occurs in the flowing current (Io> Io2), so that the external zero generated by the electromotive force generated by the internal zero-phase current transformer ZCT2-1 generated by the zero-phase current Io and the shunt current Io2 The electromotive force generated by the phase current transformer ZCT2-2 is not the same, but the polarity is the same direction. Therefore, the difference between the electromotive forces is reversed to the internal zero-phase current transformer ZCT2-1 and the external zero-phase current transformer ZCT2-2. Polarity voltage will be generated. However, since the internal zero-phase current transformer ZCT2-1 has a larger electromotive force than the external zero-phase current transformer ZCT2-2, the secondary current io2 increases from negative polarity to positive as shown in FIG. When the polarity is reversed, the voltage of the internal zero-phase current transformer ZCT2-1, the voltage V2-1 (the integrated value of the predetermined time ti, the average value calculated from it, or the effective value) is positive, and is monitored. The wirings 3C and 4C are cut off based on a circuit leakage accident.

  Further, in the detection circuit 6D on the 100V side, a current flows in the reverse direction (negative direction) through the internal zero-phase current transformer ZCT1-1, and the external zero-phase current transformer ZCT1-2 provided in the class B grounding wire 5 Since current flows in the forward direction, each flows in the opposite direction. In the detection circuit 6D, the secondary current io1 of the internal zero-phase current transformer ZCT1-1 is converted into the external zero-phase current transformer ZCT1- by the zero-phase current Io2 that flows to the primary side of the external zero-phase current transformer ZCT1-2. 2 is higher than the voltage V1-1 generated on the secondary side, the secondary current io1 is a current flowing by the voltage V1-2. For this reason, when io1 is inverted from the negative pole to the positive pole, the secondary voltage VZCT1-1 of the internal zero-phase current transformer ZCT1-1 (the integrated value of the predetermined time ti or the average value and the effective value calculated therefrom). ) Is a negative electrode, it can be determined that this is a leakage of a circuit that is not monitored. For this reason, blocking is prevented.

  8A, since the current Io flowing through the internal zero-phase current transformer ZCT2-1 of the 200V detection circuit 6C is larger than the current Io2 flowing through the external zero-phase current transformer ZCT2-2, the detection circuit 6C The flowing secondary current io2 is in the same direction as the voltage V2-1. For this reason, the voltage polarity of the internal zero phase current transformer ZCT2-1 at the time when the secondary current io2 changes to a positive polarity is positive. Next, as the magnitude of the shunted Io1 flowing through the wiring 4D becomes smaller, the voltage V1-1 generated in the internal zero-phase current transformer ZCT1-1 of the 100V side leakage breaker 1D is shown in FIG. 8B. Thus, when it becomes small and does not divert, it will be in the state shown in FIG.5 and FIG.7.

  From the above, in the earth leakage circuit breaker 1 according to the present invention, the secondary side of the internal zero-phase current transformer ZCT1 and the secondary of the external zero-phase current transformer ZCT2 provided on the shared B-type grounding wire are used. Are connected in series, and the parameter based on the secondary current flowing through this and the voltage generated on the secondary side of the internal zero coarse current transformer ZCT1 (from the time when the secondary current changes from the minus pole to the plus pole) Based on the integration amount of the voltage within a predetermined time, or the average value, effective value, etc. calculated from this integration amount), the leakage is a leakage accident (internal accident) of the monitored circuit, or the leakage of the circuit that is not monitored It is possible to reliably determine whether the accident (external accident).

1, 1A, 1B, 1C, 1D Leakage breaker 2 Control circuit 3, 3A, 3B, 3C, 3D, 4, 4A, 4B, 4C, 4D Wiring 5 Type B ground line 6C, 6D Detection circuit 7 Voltage suppression element 10 , 11 Single-phase transformer 12 Three-phase transformer

Claims (5)

In the earth leakage circuit breaker used for the equipment configuration sharing the B class grounding wire with multiple transformers,
An external zero-phase current transformer is provided on the B-type ground wire,
The secondary side of the internal zero phase current transformer provided in the earth leakage circuit breaker and the secondary side of the external zero phase current transformer are connected in series to constitute a detection circuit,
Zero-phase current detection means for detecting a current flowing through the detection circuit;
Secondary side voltage detecting means for detecting a secondary side voltage of the internal zero phase current transformer;
A parameter based on the secondary side voltage of the internal zero phase current transformer detected by the secondary side voltage detection means when the zero phase current detected by the zero phase current detection means is greater than or equal to a first predetermined value. Is within a predetermined range around zero, or a second parameter whose parameter based on the secondary side voltage of the internal zero-phase current transformer detected by the secondary side voltage detecting means is larger than a predetermined range around zero. When it is equal to or greater than a predetermined value, a leakage processing means that determines that the leakage of the monitoring target circuit of the leakage breaker is a leakage and interrupts the circuit;
A parameter based on the secondary side voltage of the internal zero phase current transformer detected by the secondary side voltage detection means when the zero phase current detected by the zero phase current detection means is greater than or equal to a first predetermined value. Interruption preventing means for invalidating the interruption of the circuit by judging that the leakage of the circuit not monitored by the leakage breaker is a leakage when the current is not within a predetermined range around zero and not more than the second predetermined value An earth leakage circuit breaker comprising:   The parameter based on the secondary side voltage is an integral value of the secondary side voltage within a predetermined time from the time when the polarity of the zero phase current detected by the zero phase current detecting means is reversed from the minus pole to the plus pole. The earth leakage circuit breaker according to claim 1.   The parameter based on the secondary side voltage is an average value of the secondary side voltage within a predetermined time from the time when the polarity of the zero phase current detected by the zero phase current detecting means is reversed from the negative pole to the positive pole. The earth leakage circuit breaker according to claim 1.   3. The earth leakage circuit breaker according to claim 2, wherein the predetermined time is 4 ms.   The earth leakage circuit breaker according to any one of claims 1 to 4, wherein the detection circuit includes a voltage suppression element so that the voltage does not exceed a predetermined value.

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