Electric leakage detection device

Abstract

To provide a leakage detection device capable of improving maintainability.SOLUTION: An electric leakage detection device according to the present disclosure includes a housing, a first zero phase current transformer through which a first electric wire and a second electric wire pass, a relay for electric leakage detection output, a test switch that is provided so as to be operable from the outside of the housing and operates the relay by being operated from the outside of the housing, and a first electric leakage detection circuit that operates the relay based on a current output from the first zero phase current transformer due to an electric leakage current flowing through the first electric wire and operates the relay based on a current output from the first zero phase current transformer due to a test current flowing through the second electric wire.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an earth leakage detection device. [Background technology]

[0002] There is known a leakage current detection device that has a test switch to check whether the leakage current detection function and the trip function are operating normally. Patent Document 1 describes an earth leakage circuit breaker that has a test circuit that supplies a test current that simulates an earth leakage current to a zero-phase current transformer when the test switch is turned on. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-220382 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 leaves room for improvement in maintainability, as it is time-consuming to switch the sensitivity when passing the sensitivity standard and test current in the test circuit installed inside the earth leakage breaker, and it is necessary to disconnect the ground wiring when performing a test.

[0005] The present disclosure provides a leakage detection device that can improve maintainability. [Means for solving the problem]

[0006] The present disclosure provides a display device comprising: a housing; a first zero-phase current transformer through which the first electric wire and the second electric wire pass; A relay for outputting leakage current detection; a test switch that is operable from outside the housing and that operates the relay when operated from outside the housing; a first leakage detection circuit that operates the relay based on a current output from the first zero-phase-sequence current transformer due to a leakage current flowing through the first electric wire, and that operates the relay based on a current output from the first zero-phase-sequence current transformer due to a test current flowing through the second electric wire; The present invention provides a leakage current detection device comprising: [Effects of the Invention]

[0007] According to the electric leakage detection device according to the present disclosure, it is possible to improve maintainability. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of the configuration of an electric leakage detection device according to a first embodiment of the present disclosure. [Figure 2] 2 is a diagram for explaining a first signal path and a second signal path in the electric leakage detection device according to the first embodiment of the present disclosure. FIG. [Figure 3] 2 is a diagram illustrating an example of a circuit configuration of a test switch and an operation display unit of the electric leakage detection device according to the first embodiment of the present disclosure. FIG. [Figure 4] 2 is a diagram illustrating an example of the appearance of one surface of a housing of the electric leakage detection device according to the first embodiment of the present disclosure. FIG. [Figure 5] FIG. 10 is a diagram illustrating a configuration example of an electric leakage detection device according to a second embodiment of the present disclosure. [Figure 6] FIG. 10 is a diagram illustrating an example of a circuit configuration of a second sensitivity setting circuit of an electric leakage detection device according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configuration are designated by the same reference numerals, and redundant description will be omitted.

[0010] [First embodiment] 1 is a diagram showing an example of the configuration of a ground fault detection device 1 according to a first embodiment of the present disclosure. The ground fault detection device 1 is a device that detects a ground fault and, if a ground fault is detected, generates a ground fault detection output indicating that a ground fault has been detected. The ground fault detection device 1 is also called a ground fault relay. The ground fault detection device 1 includes a housing 2, a test switch 3, a sensitivity changeover switch 4, an operation display unit 5, an input terminal block 6, a power supply unit 10, and a control unit 20.

[0011] The housing 2 may be made of iron or plastic, but if the housing 2 is made of iron, the influence of external noise can be suppressed.

[0012] The test switch 3 is provided so as to be operable from outside the housing 2. The test switch 3 is a switch for detecting whether or not there is a malfunction in the earth leakage detection device 1 (particularly the relay 13). The test switch 3 may be, but is not limited to, a push button type. When operated from outside the housing 2, the test switch 3 operates the relay 13 for outputting the earth leakage detection signal. The operation of the relay when the test switch 3 is operated will be explained later using Figure 2. Note that, hereinafter, the act of turning on the test switch 3 will also be referred to as "turning on the test switch 3."

[0013] The sensitivity changeover switch 4 can set a plurality of rated sensitivity current values ​​in the first sensitivity setting circuit 23. The rated sensitivity current values ​​may be, for example, but are not limited to, 15 mA, 30 mA, 100 mA, and 500 mA. The sensitivity changeover switch 4 may also be configured to be able to switch the rated sensitivity current value by rotating it, like a rotary switch, but is not limited to this and may have any configuration that allows switching between a plurality of rated sensitivity current values.

[0014] The operation display unit 5 displays the operation of the relay 13 due to the detection of a ground fault or the execution of a test. The operation display unit 5 may be configured with an LED (Light Emitting Diode), but is not limited to this. The display by the operation display unit 5 may be a lit or flashing light.

[0015] The input terminal block 6 includes a first connection terminal 61a electrically connected to one end of the first electric wire 61, a second connection terminal 61b electrically connected to the other end of the first electric wire 61, a third connection terminal 62a electrically connected to one end of the second electric wire 62, and a fourth connection terminal 62b electrically connected to the other end of the second electric wire 62. The first connection terminal 61a, the second connection terminal 61b, the third connection terminal 62a, and the fourth connection terminal 62b are provided outside the housing 2.

[0016] The first connection terminal 61a and the second connection terminal 61b are electrically connected to an electric circuit to be detected for leakage current. For example, when the first connection terminal 61a is electrically connected to the electric circuit via a first ground wire and the second connection terminal 61b is grounded via a second ground wire, the leakage current detection device 1 can detect a ground fault current flowing in the ground wiring (the first ground wire, the first electric wire 61, and the second ground wire). A tester capable of passing a test current equivalent to the current when a leakage current occurs is connected to the third connection terminal 62a and the fourth connection terminal 62b. By passing the test current from the tester through the second electric wire 62, the characteristics of the leakage current detection device 1 can be evaluated.

[0017] Furthermore, with the above-described structure, a testing device can be connected to the third connection terminal 62a and the fourth connection terminal 62b while the electrical circuit to be detected for leakage current remains electrically connected to the first connection terminal 61a and the second connection terminal 61b.

[0018] The power supply unit 10 includes a relay drive circuit 11, a DC-DC converter 12, and a relay 13. The relay drive circuit 11 receives a relay drive signal accompanying the operation of the test switch 3, and operates the relay 13. The relay drive circuit 11 also receives a relay drive signal based on the result of the determination by the first determination circuit 24 as to the presence or absence of a leakage current or a test current, and operates the relay 13. When the relay 13 operates, the earth leakage detection device 1 generates an earth leakage detection output indicating that an earth leakage has been detected. When a circuit breaker (not shown) installed outside the earth leakage detection device 1 detects the earth leakage detection output, it instantaneously breaks the electrical path electrically connected to the first connection terminal 61a.

[0019] The DC-DC converter 12 converts the voltage from the external power supply into an internal power supply voltage for operating the control unit 20 and the relay drive circuit 11. The rated value of the internal power supply voltage can be various values, such as 24 V and 12 V. An output terminal block may be provided on the power supply unit 10 side of the housing 2.

[0020] Here, the first signal path and the second signal path in the earth leakage detection device 1 according to this embodiment will be described with reference to Fig. 2. In the figure, R1 indicates the first signal path, and R2 indicates the second signal path. Each component in the figure is the same as each component shown in Fig. 1.

[0021] The relay driving circuit 11 may include a transistor 14. The transistor 14 is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), but is not limited to this and may be another semiconductor switch such as a bipolar transistor. The relay 13 has a coil 15 and a switch 19.

[0022] The relay drive circuit 11 operates the relay 13 by passing a current that turns on the switch 19 through the coil 15 and the test switch 3 based on a relay drive signal generated by operation of the test switch 3. Alternatively, the relay drive circuit 11 operates the relay 13 by passing a current that turns on the switch 19 through the coil 15 and the transistor 14 based on a relay drive signal generated based on the result of determination by the first determination circuit 24 as to whether or not there is a leakage current.

[0023] The DC-DC converter 12 may include a power supply circuit 16, a diode 17, and a capacitor 18. The diode 17 is a backflow prevention diode that blocks current flowing in from the output side of the power supply circuit 16, and the capacitor 18 is used to smooth the output voltage of the power supply circuit 16.

[0024] The first signal path R1 is a path through which a signal flows via the test switch 3 when the test switch 3 is turned on, and which operates the relay 13. As shown in the figure, the test switch 3 is connected in parallel with the transistor 14. Furthermore, under normal circumstances when no leakage current is detected by the first determination circuit 24, the transistor 14 is in an off state. Therefore, when the test switch 3 is turned on under normal circumstances, the first signal path R1 is formed, which passes through the DC-DC converter 12, the coil 15, and the test switch 3, but does not pass through the transistor 14.

[0025] The second signal path R2 is a path through which a signal for operating the relay 13 is transmitted without passing through the test switch 3, based on a current output from the leakage detection winding of the first zero-phase-sequence current transformer 21 due to a leakage current in an electric circuit electrically connected to the third connection terminal 62a and the fourth connection terminal 62b. As shown in the figure, when a leakage current occurs in an electric circuit electrically connected to the first electric wire 61, a current is generated in the leakage current detection winding of the first zero-phase-sequence current transformer 21. Then, the second signal path R2 is formed by passing through the IV conversion circuit 22, the first sensitivity setting circuit 23, the first determination circuit 24, the transistor 14, the coil 15, and the DC-DC converter 12, without passing through the test switch 3.

[0026] That is, the test switch 3 is included in the first signal path R1 but not in the second signal path R2. Therefore, even if the electric circuit remains connected to the first electric wire 61 via the first connection terminal 61a and the second connection terminal 61b, it is possible to check whether or not the relay 13 is faulty by operating the test switch 3.

[0027] Next, the circuit configuration of the test switch 3 and the operation display unit 5 will be described with reference to Fig. 3. Fig. 3 is a diagram showing an example of the circuit configuration of the test switch 3 and the operation display unit 5 of the electric leakage detection device 1 according to this embodiment.

[0028] The test switch 3 is a switch circuit including a switch 51, a resistor 52, a resistor 53, a diode 54, a capacitor 55, and a Darlington transistor 56. The operation indicator 5 is a display circuit including an LED 57 and a resistor 58.

[0029] The switch 51 of the test switch 3 is connected between the power supply line V1 and a resistor 52. The power supply line V1 is a supply line for a first internal power supply voltage generated by the DC-DC converter 12. The switch 51 is turned on or off by a user. The resistor 53 is connected between one end of the resistor 52 and the base of a Darlington transistor 56. The diode 54 has a cathode connected between the resistors 52 and 53 and an anode connected to ground. The capacitor 55 has one end connected between the resistor 53 and the base of the Darlington transistor 56 and the other end connected to ground. The Darlington transistor 56 is connected between a node a and ground. The node a is connected to one end of the coil 15. Note that the node a shown in FIG. 2 and the node a shown in FIG. 3 are electrically the same location.

[0030] The operation indicator 5 is connected to the Darlington transistor 56 of the test switch 3 at node a. A resistor 58 and an LED 57 are connected in series between the power supply line V2 and node a. The power supply line V1 is a supply line for the second internal power supply voltage generated by the DC-DC converter 12.

[0031] When switch 51 of test switch 3 is turned on, a base current flows to the base of Darlington transistor 56 via resistors 52 and 53. When Darlington transistor 56 is turned on by the base current, current flows through coil 15, causing relay 13 to operate, and current flows through LED 57, causing LED 57 to emit light, causing operation indicator 5 to indicate the operation of relay 13.

[0032] To prevent malfunction of the relay 13, the test switch 3 operates the relay 13 with a predetermined delay from the time when the switch 51 of the test switch 3 is turned on. The predetermined delay may be, for example, about 0.5 seconds. For example, the combined resistance value of the resistors 52 and 53 may be 100 kΩ, and the capacitance of the capacitor 55 may be 4.7 μF. In this case, the time constant of the test switch 3 is 100 kΩ × 4.7 μF = 0.47 seconds, and the relay 13 operates with a delay of about 0.5 seconds from the time when the switch 51 of the test switch 3 is turned on.

[0033] When the relay 13 operates, a current flows through the LED 57 and resistor 58 of the operation indicator 5. At this time, the LED 57 lights up. Therefore, when the relay 13 operates, the operation indicator 5 lights up.

[0034] In FIG. 1, the control unit 20 includes an AC determination unit 30. The AC determination unit 30 is an example of a first leakage current detection circuit. The AC determination unit 30 includes a first zero-phase-sequence current transformer 21, an IV conversion circuit 22, a first sensitivity setting circuit 23, and a first determination circuit 24. The first zero-phase-sequence current transformer 21 is built into the housing 2 and detects leakage current in the electric circuit. A first electric wire 61 and a second electric wire 62 pass through the first zero-phase-sequence current transformer 21. The first zero-phase-sequence current transformer 21 includes a core and a leakage current detection winding. The leakage current detection winding is wound around the core. The AC determination unit 30 detects AC leakage current flowing in the first electric wire 61.

[0035] When a leakage current flows in the first electric wire 61 or when a test current flows in the second electric wire 62, a current is generated in the leakage detection winding of the first zero-phase-sequence current transformer 21, and the generated current flows to the IV conversion circuit 22. The first determination circuit 24 determines whether or not a leakage current flows in the first electric wire 61 and whether or not a test current flows in the second electric wire 62, based on the output current of the leakage detection winding of the first zero-phase-sequence current transformer 21. The first determination circuit 24 may also amplify the current from the first zero-phase-sequence current transformer 21. In this case, the first determination circuit 24 determines whether or not a leakage current and a test current exist, based on the amplified current value.

[0036] The IV conversion circuit 22 converts the value of the current detected by the first zero-phase-sequence current transformer 21 into a voltage value. The IV conversion circuit 22 may convert the value of the current output from the first zero-phase-sequence current transformer 21 into a voltage value using a load resistor selected by the first sensitivity setting circuit 23. The resistance value of the load resistor is switched according to the rated sensitivity current value set by the first sensitivity setting circuit 23 in response to operation of the sensitivity changeover switch 4.

[0037] The first sensitivity setting circuit 23 is connected to the first determination circuit 24 and can set a rated sensitivity current value that determines the sensitivity for detecting leakage current. The first sensitivity setting circuit 23 may have a load resistor corresponding to the set rated sensitivity current value. The first sensitivity setting circuit 23 may have a switch, and may select a load resistor having a resistance value corresponding to the set rated sensitivity current value by using the switch to connect to the IV conversion circuit 22.

[0038] The first determination circuit 24 may include a comparison circuit. The first determination circuit 24 may use the comparison circuit to compare a voltage threshold corresponding to a preset leakage current value with the voltage value supplied from the IV conversion circuit 22 via the first sensitivity setting circuit 23, and transmit a relay drive signal based on the determination result of the presence or absence of leakage current or test current to the relay drive circuit 11. For example, the first determination circuit 24 transmits the relay drive signal when a leakage current or test current is detected, and does not transmit the relay drive signal when a leakage current or test current is not detected.

[0039] 4 is a diagram showing an example of the appearance of one surface of the housing 2 of the earth leakage detection device 1 according to the first embodiment of the present disclosure. As shown in the figure, the test switch 3 is provided so as to be operable from outside the housing 2. In addition, a sensitivity changeover switch 4 and an operation display unit 5 are provided on one surface of the housing 2.

[0040] In the illustrated example, the rated sensitivity current values ​​are 15 mA, 30 mA, 100 mA, and 500 mA. Note that the arrangement of the test switch 3, sensitivity changeover switch 4, and operation display unit 5 is not limited to the illustrated example.

[0041] To prevent malfunction, the test switch 3 is preferably embedded in the housing 2. The test switch 3 may be a push button type, or may have a structure that allows it to be pressed with a thin rod-like pin.

[0042] The sensitivity selector switch 4 is preferably embedded in the housing 2 to prevent malfunction. The sensitivity selector switch 4 may be configured to be rotatable like a rotary switch. Alternatively, the sensitivity selector switch 4 may be configured to be rotatable by inserting a tool such as a flathead screwdriver. By operating the sensitivity selector switch 4, the rated sensitivity current value can be switched to, for example, any of 15 mA, 30 mA, 100 mA, and 500 mA.

[0043] The operation indicator 5 may be configured with, for example, a red LED, and may be lit while a leakage current is detected or while the test switch 3 is pressed. While an AC leakage current of a predetermined frequency or less is detected by the first determination circuit 24 of the AC determination unit 30, the operation indicator 5 flashes at the same cycle as the cycle in which the relay 13 is repeatedly turned on and off by the transistor 14 being turned on and off.

[0044] In conventional leakage current detection devices, the rated sensitivity current value of the sensitivity setting circuit installed inside the housing is often constant, and if you want to change the rated sensitivity current value, you have to use another leakage current detection device with a different standard.

[0045] In the leakage current detection device 1 of this embodiment, the rated sensitivity current value can be easily set using the sensitivity changeover switch 4 connected to the first sensitivity setting circuit 23, and the required detection sensitivity of the test current or the sensitivity for determining whether or not there is a leakage current can be switched.

[0046] In addition, in conventional earth leakage detection devices, a test current generating circuit is often connected to a test winding provided in the zero-phase current transformer separately from the earth leakage detection winding to determine whether the earth leakage detection device is faulty. In such cases, when conducting a test current, it is necessary to remove the wiring electrically connected to the electric wire passing through the zero-phase current transformer.

[0047] The earth leakage detection device 1 according to this embodiment includes a first connection terminal 61a electrically connected to one end of the first electric wire 61, a second connection terminal 61b electrically connected to the other end of the first electric wire 61, a third connection terminal 62a electrically connected to one end of the second electric wire 62, and a fourth connection terminal 62b electrically connected to the other end of the second electric wire 62. Therefore, a tester can be connected to the third connection terminal 62a and the fourth connection terminal 62b while the electric circuit to be detected for earth leakage remains connected to the first connection terminal 61a and the second connection terminal 61b.

[0048] The earth leakage detection device 1 also includes a first sensitivity setting circuit 23 that can set multiple rated sensitivity current values, and a sensitivity changeover switch 4. This eliminates the need to replace the product depending on the required earth leakage detection sensitivity. The earth leakage detection device 1 also includes a test switch 3 that can be operated from outside the housing 2. When the test switch 3 is turned on, the earth leakage detection device 1 includes a path (first signal path R1 that operates the relay 13) that is different from the second signal path R2, which is the earth leakage detection path of the electric circuit, and therefore, a test for the purpose of checking the operation of the relay 13 can be easily performed.

[0049] Therefore, according to the electric leakage detection device 1 according to this embodiment, it is possible to improve maintainability.

[0050] [Second embodiment] 5 is a diagram showing an example of the configuration of a ground fault detection device 1 according to a second embodiment of the present disclosure. In the second embodiment, the same configuration, actions, and effects as those of the first embodiment will not be described here, as the above description is incorporated. The ground fault detection device 1 according to the second embodiment includes a housing 2, a test switch 3, a sensitivity changeover switch 4, an operation display unit 5, an input terminal block 6, a power supply unit 10, and a control unit 20.

[0051] The input terminal block 6 includes a first connection terminal 61a electrically connected to one end of the first electric wire 61, a second connection terminal 61b electrically connected to the other end of the first electric wire 61, a third connection terminal 62a electrically connected to one end of the second electric wire 62, and a fourth connection terminal 62b electrically connected to the other end of the second electric wire 62. The power supply unit 10 also includes a relay drive circuit 11, a DC-DC converter 12, and a relay 13. Unlike the first embodiment, the earth leakage detection device 1 according to the second embodiment detects AC earth leakage current and DC earth leakage current.

[0052] The control unit 20 includes a first zero-phase-sequence current transformer 21, an IV conversion circuit 22, a first sensitivity setting circuit 23, and a first judgment circuit 24, and the component including these is referred to as the "AC judgment unit 30." The control unit 20 also includes a second zero-phase-sequence current transformer 25, an oscillation / detection circuit 26, a second sensitivity setting circuit 27, and a second judgment circuit 28, and the component including these is referred to as the "DC judgment unit 40." The AC judgment unit 30 is a component that determines the presence or absence of an AC leakage current and an AC test current, and the DC judgment unit 40 is a component that determines the presence or absence of a DC leakage current and a DC test current. The AC judgment unit 30 is an example of a first leakage detection circuit. The DC judgment unit 40 is an example of a second leakage detection circuit.

[0053] Furthermore, a first electric wire 61 and a second electric wire 62 pass through the first zero-phase-sequence current transformer 21 and the second zero-phase-sequence current transformer 25, respectively. The AC determination unit 30 operates the relay 13 based on the current output from the first zero-phase-sequence current transformer 21 due to an AC leakage current flowing in the first electric wire 61, and also operates the relay 13 based on the current output from the first zero-phase-sequence current transformer 21 due to an AC test current flowing in the second electric wire 62. The DC determination unit 40 operates the relay 13 based on the current output from the second zero-phase-sequence current transformer 25 due to a DC leakage current flowing in the first electric wire 61, and also operates the relay 13 based on the current output from the second zero-phase-sequence current transformer 25 due to the DC test current flowing in the second electric wire 62.

[0054] The first determination circuit 24 of the AC determination unit 30 is an AC determination circuit that determines the presence or absence of an AC leakage current and an AC test current based on the output current of the leakage detection winding of the first zero-phase-sequence current transformer 21, which is for AC. The second determination circuit 28 of the DC determination unit 40 is a DC determination circuit that determines the presence or absence of a DC leakage current and a DC test current based on the output current of the leakage detection winding of the second zero-phase-sequence current transformer 25, which is for DC.

[0055] The oscillation / detection circuit 26 included in the DC determination unit 40 may excite the core of the second zero-phase-sequence current transformer 25 by, for example, self-oscillation, and output a pulse whose duty ratio changes according to the magnitude of the leakage current. At this time, the second determination circuit 28 may determine the presence or absence of leakage based on the pulse output by the oscillation / detection circuit 26. Furthermore, the relay drive circuit 11 may perform control so that the relay 13 does not operate until the operation of the oscillation / detection circuit 26 stabilizes after power is turned on.

[0056] A relay drive signal based on the determination results of the first determination circuit 24 and the second determination circuit 28 as to whether or not there is a leakage current or a test current is transmitted to the relay drive circuit 11 via the OR circuit 29. The OR circuit 29 is a logical OR circuit that outputs a relay drive signal that is the logical OR of the relay drive signal based on the determination result of the first determination circuit 24 as to whether or not there is a leakage current or a test current, and the relay drive signal based on the determination result of the second determination circuit 28 as to whether or not there is a leakage current or a test current. The relay drive circuit 11 receives the relay drive signal from the OR circuit 29 and operates the relay 13. By using the OR circuit 29, the earth leakage detection device 1 can operate the relay 13 whether or not an AC leakage current or a test current is detected.

[0057] The sensitivity changeover switch 4 can set a plurality of rated sensitivity current values ​​to each of the first sensitivity setting circuit 23 of the AC judging section 30 and the second sensitivity setting circuit 27 of the DC judging section 40.

[0058] 6 is a diagram showing an example of the configuration of the second sensitivity setting circuit 27 of the earth leakage detection device 1 according to the second embodiment. The second sensitivity setting circuit 27 includes resistors 71, 72, 73, and 74, a switch 75, an operational amplifier 76, and a resistor 77.

[0059] In the second sensitivity setting circuit 27, four resistors 71, 72, 73, and 74 are connected in parallel to a switch 75. The second sensitivity setting circuit 27 has an inverting amplifier circuit configured by connecting one of the four resistors 71, 72, 73, and 74 selected by the switch 75 to an operational amplifier 76 and a resistor 77.

[0060] The gain of the inverting amplifier circuit is determined based on one of resistors 71, 72, 73, and 74 and resistor 77. Therefore, switch 75 selects the resistor to be connected to the inverting input terminal of operational amplifier 76 from resistors 71, 72, 73, and 74 in accordance with the rated sensitivity current value set by sensitivity selector switch 4.

[0061] For example, assume that the rated sensitivity current value is one of 15 mA, 30 mA, 100 mA, and 500 mA. If the rated sensitivity current value is 15 mA, switch 75 selects resistor 71. If the rated sensitivity current value is 30 mA, switch 75 selects resistor 72. If the rated sensitivity current value is 100 mA, switch 75 selects resistor 73. If the rated sensitivity current value is 500 mA, switch 75 selects resistor 74.

[0062] Here, the resistance value of resistor 77 is set to 220 kΩ. If the resistance value of resistor 71 selected by switch 75 is set to 5.26 kΩ when the rated sensitivity current value is 15 mA, the amplification factor of the inverting amplifier circuit is (220 kΩ / 5.26 kΩ) = 41.8 times.

[0063] Furthermore, if the resistance value of resistor 72 selected by switch 75 when the rated sensitivity current value is 30 mA is 10.39 kΩ, then the amplification factor of the inverting amplifier circuit is similarly (220 kΩ / 10.39 kΩ)=21.2 times.

[0064] Furthermore, if the resistance value of resistor 73 selected by switch 75 when the rated sensitivity current value is 100 mA is 36.9 kΩ, then the amplification factor of the inverting amplifier circuit is similarly (220 kΩ / 36.9 kΩ)=6.59 times.

[0065] Furthermore, if the resistance value of resistor 74 selected by switch 75 when the rated sensitivity current value is 500 mA is 134.0 kΩ, then the amplification factor of the inverting amplifier circuit is similarly (220 kΩ / 134.0 kΩ)=1.69 times.

[0066] In this way, the inverting amplifier circuit amplifies the voltage from the oscillation / detection circuit 26 in accordance with the set rated sensitivity current value. The voltage amplified by the inverting amplifier circuit is output to the second determination circuit 28.

[0067] The second determination circuit 28 may include a comparison circuit. Using the comparison circuit, the second determination circuit 28 compares a voltage threshold corresponding to a preset leakage current value with the voltage value supplied from the oscillation / detection circuit 26 via the second sensitivity setting circuit 27, and transmits a relay drive signal based on the determination result of the presence or absence of leakage current or test current to the OR circuit 29. For example, the second determination circuit 28 transmits the relay drive signal when a leakage current or test current is detected, and does not transmit the relay drive signal when neither a leakage current nor a test current is detected.

[0068] The earth leakage detection device 1 according to the second embodiment includes an AC determination unit 30 that is a component that determines an AC leakage current or a test current, and a DC determination unit 40 that is a component that determines a DC leakage current or a test current. Therefore, in addition to the effects of the earth leakage detection device 1 according to the first embodiment, the earth leakage detection device 1 according to the second embodiment can improve maintainability whether the current to be detected is AC or DC.

[0069] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims.

[0070] For example, the electric leakage detection device 1 according to the first embodiment includes an AC determination unit 30, and the electric leakage detection device 1 according to the second embodiment includes both the AC determination unit 30 and the DC determination unit 40. As a modification, the electric leakage detection device 1 according to the first embodiment may include a DC determination unit 40 instead of the AC determination unit 30. [Explanation of symbols]

[0071] 1. Electric leakage detection device 2. Case 3 Test Switch 4 Sensitivity switch 10 Power supply section 11 Relay drive circuit 13 Relay 20 Control Unit 21 1st zero phase current transformer 23 First sensitivity setting circuit 24 1st judgment circuit 25 2nd zero phase current transformer 27 Second sensitivity setting circuit 28 Second judgment circuit 61 First Electric Wire 61a First connection terminal 61b Second connection terminal 62 Second Electric Wire 62a Third connection terminal 62b 4th connection terminal

Claims

1. The housing and a first zero-phase current transformer through which the first electric wire and the second electric wire pass; A relay for outputting leakage current detection; a test switch that is operable from outside the housing and that operates the relay when operated from outside the housing; a first leakage detection circuit that operates the relay based on a current output from the first zero-phase-sequence current transformer in response to a leakage current flowing through the first electric wire, and that operates the relay based on a current output from the first zero-phase-sequence current transformer in response to a test current flowing through the second electric wire; A leakage current detection device comprising:

2. a first sensitivity setting circuit that sets a leakage detection sensitivity in the first leakage detection circuit; a sensitivity changeover switch that is operable from outside the housing and that changes the leakage detection sensitivity set for the first sensitivity setting circuit by being operated from outside the housing; The earth leakage detection device according to claim 1 .

3. a second zero-phase current transformer through which the first electric wire and the second electric wire pass; a second leakage detection circuit that operates the relay based on a current output from the second zero-phase-sequence current transformer due to a leakage current flowing through the first electric wire, and that operates the relay based on a current output from the second zero-phase-sequence current transformer due to a test current flowing through the second electric wire, One of the first leakage current detection circuit and the second leakage current detection circuit detects an AC current flowing through the first electric wire or the second electric wire, and the other detection circuit detects a DC current flowing through the first electric wire or the second electric wire. The earth leakage detection device according to claim 1 .

4. a second sensitivity setting circuit that sets a leakage detection sensitivity in the second leakage detection circuit; a sensitivity changeover switch for changing the leakage detection sensitivity set in the second sensitivity setting circuit, The earth leakage detection device according to claim 3.

5. a first connection terminal provided outside the housing and electrically connected to one end of the first electric wire; a second connection terminal provided outside the housing and electrically connected to the other end of the first electric wire; a third connection terminal provided outside the housing and electrically connected to one end of the second electric wire; a fourth connection terminal provided outside the housing and electrically connected to the other end of the second electric wire, The earth leakage detection device according to any one of claims 1 to 4.

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