JP2001258149A - Transmission and distribution apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission and distribution apparatus capable of reducing an influence caused by a wraparound of high-frequency leakage current, ground current, constant leakage current or the like, and operating a ground leakage breaker positively. SOLUTION: Ground potential suppressors 1A, 1B are provided between a ground terminal on the low-voltage side of single- and three-phase high/low voltage transformers and a ground pole Eb (for example, class B ground). The ground leakage breakers are mounted on respective low-voltage side electric wires of the high/low voltage transformer. One terminal of ground capacitors C1-C3 is connected between a low-voltage side winding Tr2S of the three-phase three-line high/low voltage transformer Tr2 and the earth leakage breaker. The other terminal of the ground capacitors C1-C3 is connected in common, and a switch 3 serving as an electric wire switching means is provided between a common connection and the ground pole Eb (for example, class D ground). A ground leakage breaker controller 4 on/off-controls the switch 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission and distribution device capable of reducing the influence of a ground fault current, a high-frequency current, and the like.

[0002]

2. Description of the Related Art Conventionally, power transmission and distribution devices for supplying power include:
A three-phase three-wire high-low voltage transformer, a single-phase three-wire high-low voltage transformer, and the like are used. Grounding work may be performed on the neutral point of the low-voltage side winding of the high-low voltage transformer or one of the low-voltage side winding terminals. FIG. 9 shows a single-phase three-wire high / low voltage transformer T
The ground terminal N of the low-voltage winding of r1 and the ground terminal TE of the low-voltage winding of the three-phase three-wire high-low voltage transformer Tr2 are connected to the ground electrode E.
FIG. 4 is a schematic diagram showing that the connection is made to a terminal b (for example, a class B ground). A load 5 is connected to the low-voltage side electric circuit of the three-phase three-wire high / low voltage transformer Tr2, and a ground terminal of the load 5 is connected to a ground electrode Ed (for example, a D-class ground).

[0003]

According to such a grounding method, there are the following problems. In recent years, the cables of the low-voltage side electric circuit of the single-phase three-wire high-low voltage transformer Tr1 and the three-phase three-wire high-low voltage transformer Tr2 have become longer. Also, an electronic device having a built-in line filter or the like having a capacitor as a constituent element is often connected as a load. Therefore, generally, as shown in FIG. 5, the ground capacitance (stray capacitance) 10 of the low-voltage side electric circuit is large. In such a power transmission and distribution facility, when an inverter or the like is connected as the load 5, the high-frequency leakage current 12 as shown in FIG.
Ground capacitance (floating capacitance) 10, earth leakage breaker ELCB
1, flows into a closed circuit formed by the low-voltage side electric circuit of the single-phase three-wire high-low voltage transformer Tr1, the ground line 31, and the low-voltage side electric circuit of the three-phase three-wire high-low voltage transformer Tr2. Therefore, the high-frequency leakage current 12 causes an electronic device connected to the low-voltage side electric circuit of the single-phase three-wire high-low voltage transformer Tr1 to malfunction or the leakage breaker ELCB1 to trip unnecessarily. In addition, there is a possibility that devices installed in the vicinity are affected by the electromagnetic waves of the high-frequency leakage current 12. As shown in FIG. 6, a three-phase three-wire high-low voltage transformer Tr2
When the cable of the low voltage side electric circuit, for example, the cable 13 is grounded to a conduit (not shown) grounded to the ground electrode Ed, for example, a ground fault current 14 flows through a ground fault point. As shown by a broken line, the ground fault current 14 includes a ground fault point having a ground fault resistance 15, a ground wire 30 connected to a conduit, a ground capacitance (floating capacitance) 10, a ground leakage breaker ELCB1, a single phase. The low-voltage side electric circuit of the three-wire high-low voltage transformer Tr1, the ground line 31,
It flows to a closed circuit formed by the low-voltage side electric circuit of the three-phase three-wire high / low voltage transformer Tr2. In this case, when the ground capacitance 10 is large, the earth leakage breaker ELCB1 provided on the low voltage side electric circuit of the sound single-phase three-wire high-low voltage transformer Tr1 irrespective of the ground fault unnecessarily trips. there is a possibility. As shown in FIG. 7, a single-phase three-wire high-low voltage transformer Tr1
The leakage current 16 always flows through the ground capacitance 10 of the low-voltage side electric circuit. If the ground capacitance (stray capacitance) 10 of the low-voltage side electric circuit is large, the leakage current 16 always increases,
There is a possibility that the earth leakage breaker ELCB1 provided on the low voltage side electric circuit of the single-phase three-wire type high / low voltage transformer Tr1 may unnecessarily trip. Further, in such a grounding method, since the zero-sequence impedance is small, the ground fault current becomes large, which may adversely affect the electric equipment of the load.

As described above, a single-phase three-wire high / low voltage transformer Tr
Since the low-voltage side electric circuit of the one- and three-phase three-wire high-low voltage transformer Tr2 is always connected to the ground electrode Eb, the above-described problem occurs. Therefore, an object of the present invention is to provide a power transmission and distribution facility that can reduce the influence of the sneak of a high-frequency leakage current and the like.

[0005]

For this reason, the invention according to claim 1 provides at least one power transmission / distribution circuit provided with an earth leakage breaker and a power supply side of the at least one power transmission / distribution circuit with respect to the earth leakage breaker. A ground potential suppressing device provided between the ground terminal of the power supply side electric circuit and the first grounding electrode, and a power supply side electric circuit on the power supply side of the earth leakage breaker and at least one of the at least one transmission and distribution electric circuit. And an opening / closing means provided between the control circuit and the control means for controlling the opening / closing means.The ground potential suppressing device is configured to control the power transmission / distribution circuit when the voltage of at least one power transmission / distribution circuit is equal to or higher than a set value. When the ground terminal is connected to the first ground electrode, the control means controls the opening / closing means when detecting that at least one power transmission / distribution circuit has a ground fault, and controls the impedance circuit to connect the power transmission / distribution circuit to the second ground electrode. Connect between It is transmission and distribution apparatus and said. According to the power transmission and distribution device of the first aspect, it is possible to reduce the influence of the sneak path of the high-frequency leakage current and the like, and to reliably operate the leakage breaker.
Thereby, safety is improved.

[0006] The invention described in claim 2 is the invention according to claim 1.
Wherein the at least one power transmission / distribution circuit is provided with a high / low voltage transformer on the power supply side. According to the power transmission and distribution device of the second aspect, the safety when the low-voltage side electric circuit of the high / low voltage transformer is grounded is improved.

According to a third aspect of the present invention, there is provided at least one power transmission / distribution circuit provided with an earth leakage breaker, a high / low voltage transformer provided on a power supply side of at least one power transmission / distribution circuit, An impedance circuit provided between a power supply side electric circuit on a power supply side of an earth leakage breaker and a second ground electrode of at least one transmission / distribution electric circuit, which is grounded to a ground electrode of the high / low voltage transformer. And control means for controlling the switching means, wherein the control means controls the switching means when detecting that at least one power transmission / distribution circuit is grounded, and causes the impedance circuit to be connected to the power transmission / distribution circuit. The power transmission and distribution device is connected between the power transmission and distribution grounds. According to the power transmission and distribution device of the third aspect, it is possible to reduce the influence of the sneak of the high-frequency leakage current and the like, and it is possible to reliably operate the leakage breaker. Thereby, safety is improved.

According to a fourth aspect of the present invention, there is provided a power transmission / distribution circuit provided with an earth leakage breaker, a high / low voltage transformer provided on a power supply side of the at least one power transmission / distribution circuit, A transformer provided between the low-voltage side electric circuit of the transformer and the earth leakage breaker, an impedance circuit and switching means provided between the secondary side electric circuit of the transformer and the second ground electrode, and switching means A ground terminal of an electric circuit between the low-voltage side of the high-low voltage transformer and the transformer is connected to the first ground electrode, and the control means includes a circuit for connecting at least one transmission / distribution electric circuit to a ground fault. The power transmission and distribution device is characterized in that the switching circuit is controlled to detect the occurrence of the failure and to connect the impedance circuit between the secondary circuit of the transformer and the second grounding electrode. According to the power transmission and distribution device of the fourth aspect, it is possible to reduce the influence of the sneak path of the high-frequency leakage current and the like, and to reliably operate the leakage breaker.
Thereby, safety is improved.

The invention described in claim 5 is the first invention.
5. The power transmission and distribution device according to any one of items 1 to 4, wherein the impedance circuit is configured by at least one of a capacitor, a resistor, and a reactor, and the switching unit is connected between the impedance circuit and the second ground electrode. The power transmission and distribution device is characterized in that: According to the power transmission and distribution device of the fifth aspect, the configuration of the impedance circuit is simplified.

The invention described in claim 6 is the first invention.
5. The power transmission and distribution device according to any one of claims 1 to 4, wherein the impedance circuit has a transformer, and the switching means includes a transformer.
A power transmission and distribution device is provided between a secondary winding and a second ground pole. According to the power transmission and distribution device described in claim 6, the configuration of the impedance circuit is simplified.

[0011] The invention described in claim 7 is the first invention.
7. The power transmission and distribution device according to any one of claims 6 to 6, wherein the first ground electrode and the second ground electrode are the same ground electrode. According to the power transmission and distribution device described in claim 7, grounding work is easy.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a first embodiment in which the power transmission and distribution device of the present invention is applied to a low-voltage distribution and grounding device. In the low-voltage distribution and grounding apparatus shown in FIG. 1, for example, a single-phase three-wire high-low-voltage transformer Tr for private electrical equipment in a building
One and three-phase three-wire high / low voltage transformers Tr2 are installed. The single-phase three-wire high / low voltage transformer Tr1 is, for example, a high / low voltage transformer of 6.6 kv on the high voltage side and 200v-100v on the low voltage side. Also, the three-phase three-wire high-low voltage transformer Tr2 is:
For example, a high-low voltage transformer is 6.6 kv on the high voltage side and 200 v on the low voltage side. A load 5 is connected to the low-voltage side electric circuit of the three-phase three-wire high-low voltage transformer. The load 5 has a ground terminal connected to the ground electrode Ed. The low-voltage ground terminal N of the single-phase three-wire high-low voltage transformer Tr1 and the low-voltage ground terminal TE of the three-phase three-wire high-low voltage transformer Tr2 are connected to the ground electrode Eb.
(For example, class B grounding), ground potential suppressing devices 1A and 1B are provided, respectively. An earth leakage breaker ELCB1 is provided on the low voltage side electric circuit of the single-phase three-wire high-low voltage transformer Tr1. An earth leakage breaker ELCB2 is provided on the low voltage side electric circuit of the three-phase three-wire high / low voltage transformer Tr2.
Earth leakage breaker ELCB2 and three-phase three-wire high / low voltage transformer Tr2
Are connected to one terminal of each of the grounding capacitors C1 to C3. The other terminals of the grounding capacitors C1 to C3 are commonly connected, and a switch 3 serving as an electric circuit opening / closing means is provided between the common connection point and a grounding pole Ed (for example, D-class grounding). The switch 3 is on / off controlled by the earth leakage breaker control device 4.

The ground potential suppressing devices 1A and 1B are, for example,
Arrester Zn, Triac T, Varistor Znt
And a capacitor Co. Arrester Z
n is a component having a characteristic of exhibiting a short circuit phenomenon when an overvoltage is applied and recovering insulation when the overvoltage disappears. The triac T is a bidirectional thyristor, and is an AC switching element that can maintain a bidirectional on or off stable state by gate control. An arrester Zn and a capacitor are provided between the low-voltage side ground terminal N of the single-phase three-wire high-low voltage transformer Tr1 or the low-voltage side ground terminal TE of the three-phase three-wire high-low voltage transformer Tr2 and the ground electrode Eb. Co is connected in series. A triac T is connected in parallel to a series circuit of the arrester Zn and the capacitor Co. A varistor Znt is connected between the gate terminal of the triac T and the capacitor Co.

Next, the operation of the ground potential suppressing devices 1A and 1B will be described. First, the operation of the ground potential suppressing device 1B will be described. In the normal state, the arrester Zn
Of the arrester Zn is lower than the operating voltage of the arrester Zn. Therefore, the gate voltage of the triac T is lower than the trigger voltage, and the triac T is also off. Therefore, in the normal state, the ground potential suppressing device 1B
Does not operate, the connection between the ground terminal N on the low voltage side of the single-phase three-wire type high-low voltage transformer Tr1 and the ground electrode Eb remains disconnected.

Even if a ground fault occurs in the low-voltage side electric circuit of the single-phase three-wire high-low voltage transformer Tr1, the ground potential at the point (a) does not exceed the potential for operating the arrester Zn. For this reason, the arrester Zn remains in the off state,
The triac T is also off. Therefore, single phase 3
The connection between the ground terminal N on the low voltage side of the wire type high / low voltage transformer Tr1 and the ground electrode Eb remains disconnected.

As described above, in the normal state and at the time of the ground fault of the low-voltage side electric circuit of the single-phase three-wire high / low voltage transformer Tr1, the low voltage side ground terminal N and the ground electrode of the single-phase three-wire high / low voltage transformer Tr1 are used. E
b is in a cutoff state (non-conduction state). Similarly, the ground potential suppressing device 1A connected between the ground terminal TE on the low voltage side of the three-phase three-wire high-low voltage transformer Tr2 and the ground electrode Eb also has the normal state and the three-phase three-wire high-low voltage. Transformer Tr2
Of the low-voltage side electric circuit at the time of ground fault, the three-phase three-wire high-low voltage transformer T
The state between the ground terminal TE on the low voltage side of r2 and the ground electrode Eb is in a cutoff state. Therefore, the three-phase three-wire high-low voltage transformer Tr2
Ground fault current (Fig. 6) when a ground fault occurs in the low-voltage side electric circuit of
Alternatively, a high-frequency leakage current (FIG. 5) from a load 5 such as an inverter connected to the low-voltage side electric circuit of the three-phase three-wire high-low voltage transformer Tr2 wraps around the low-voltage side electric circuit of the single-phase three-wire high-low voltage transformer Tr1. , Single-phase three-wire high-low voltage transformer Tr1
Unnecessary trips of an electric device or the like (not shown) connected to the low-voltage-side electric circuit, and malfunction of the electronic device can be prevented. Further, devices installed in the vicinity are not affected by the electromagnetic waves due to the high-frequency leakage current. Furthermore, there is no adverse effect of the constant leakage current (FIG. 7).

Next, the low-voltage side winding Tr1S and the high-voltage side winding Tr1M of the single-phase three-wire high / low voltage transformer Tr1 contact each other due to insulation breakdown or the like, and the high voltage on the high voltage side is directly applied to the low voltage side. The operation of the ground potential suppressing device 1B in the case of the above will be described. Low-voltage side winding Tr1 of single-phase three-wire high-low voltage transformer Tr1
When S and the high-voltage side winding Tr1M come into contact with each other due to dielectric breakdown or the like and a high voltage on the high voltage side is applied to the low voltage side, the ground potential at the point (A) increases. As a result, the voltage applied to the arrester Zn exceeds the operating voltage and the arrester Zn is turned on, so that a charging current flows through the capacitor Co and the potential at the point (a) rises. The potential at point (a) is varistor Z
When the potential rises to operate nt, the varistor Znt
Turns on. As a result, the discharge current of the capacitor Co flows to the gate of the triac T.
Turns on. Therefore, the single-phase three-wire high-low voltage transformer Tr
1 is connected to the ground electrode Eb, and the high voltage applied to the low voltage side of the transformer Tr1 is grounded to the ground electrode Eb. An increase in the ground potential of the side electric circuit is prevented. The above-described ground potential suppressing action by the ground potential suppressing device 1B is repeated every half cycle of the commercial power supply frequency until the circuit breaker provided on the high-voltage side electric circuit of the single-phase three-wire high / low voltage transformer Tr1 trips.

The ground potential suppressing device 1A connected between the ground terminal TE on the low voltage side of the three-phase three-wire high / low voltage transformer Tr2 and the ground electrode Eb has a ground potential suppressing effect. It is the same as suppression device 1B. That is, the ground potential suppressing device 1A does not operate in the normal state and at the time of the ground fault of the low-voltage side electric circuit of the three-phase three-wire high-low voltage transformer Tr2. Also, 3
When the low voltage side winding Tr2S and the high voltage side winding Tr2M of the phase three-wire type high / low voltage transformer Tr2 are in contact with each other due to dielectric breakdown or the like and a high voltage is applied to the low voltage side, the ground potential suppressing device 1A
Operates, and the ground terminal TE of the low-voltage side winding of the three-phase three-wire high-low voltage transformer Tr2 is connected to the ground electrode Eb. As a result, the high voltage applied to the low voltage side of the transformer Tr2 is grounded to the ground electrode Eb, so that the ground potential of the low voltage side winding and the low voltage side electric circuit of the transformer Tr2 does not increase.

As described above, the ground potential suppressing devices 1A, 1
B indicates whether the high-low voltage transformers Tr1 and Tr2 are in the normal state and the low-voltage side electric circuit has a ground fault.
Since the connection between the ground terminal on the low voltage side of Tr2 and the ground electrode Eb is interrupted, a high frequency leakage current or a ground fault current from an inverter or the like is reduced from the low voltage side electric circuit of one transformer to the low voltage side of the other transformer. It can be prevented from going around the electric circuit. As a result, the electronic device connected to the normal low-voltage side electric circuit malfunctions, the leakage breaker ELCB1 is unnecessarily tripped, and the devices installed in the vicinity are affected by the electromagnetic wave of the high-frequency leakage current. Can be prevented. Further, it is possible to prevent the influence of the leakage current at all times. When the low voltage side winding and the high voltage side winding of each of the transformers Tr1 and Tr2 contact each other due to dielectric breakdown or the like and a high voltage is applied to the low voltage side, the low voltage side ground terminal N or TE is grounded. Since it is connected to the pole Eb, it is possible to prevent the ground potential of the low-voltage side electric circuit from abnormally rising.

When the ground potential suppressing devices 1A and 1B are provided, the ground terminals N and TE are in a non-ground state during normal operation. In this case, for example, the earth leakage breaker ELCB
When one line of the load-side circuit 41 of the second circuit is grounded, the earth leakage breaker E
The current for operating the LCB2 cannot flow. For this reason, for example, as shown in FIG.
2 is connected to the power supply side electric circuit 40 on the power supply side by the earth leakage breaker ELCB.
2 for grounding capacitors C1-
It is necessary to connect to ground electrode Ed via C3. In this case, the following problem occurs. For example, when a load 5 such as an inverter is connected to the load side electric circuit 41 on the load side of the earth leakage breaker ELCB2, the high frequency leakage current 1
7 flows to the power supply side electric circuit 40 via the ground line 30, the ground capacitors C1 to C3, and the earth leakage breaker ELCB2.
Therefore, there is a possibility that the electronic device 6 connected in parallel with the load 5 or a device installed in the vicinity may cause noise interference.

Therefore, in the present embodiment, as shown in FIG. 1, a switch 3 serving as an electric circuit opening / closing means is provided between the grounding capacitors C1 to C3 and the ground electrode Ed, and the on / off of the switch 3 is controlled. An earth leakage breaker control device 4 is provided. That is, each phase electric wire R of the power supply side electric circuit 40,
S and T are connected to one terminals of ground capacitors C1, C2 and C3. Grounding capacitors C1, C
The other terminals of C2 and C3 are commonly connected, and the common connection portion is connected to one terminal (C) of the switch 3. The other terminal (d) of the switch 3 is connected to the ground line 5.
0 is connected to the ground pole Ed. When one line of the load side electric circuit 41 is grounded, the earth leakage breaker control device 4 turns on the switch 3 to connect the grounding capacitors C1 to C3 to the grounding pole Ed.

The earth leakage breaker control device 4 includes a switch control circuit 7 and a zero-phase voltage detection circuit 8. When detecting the zero-phase voltage generated between the terminals of the switch 3 when the switch 3 is turned off, the zero-phase voltage detection circuit 8 outputs a control signal for turning on the switch 3 to the switch control circuit 7. The zero-phase voltage is a voltage generated when the three-phase voltage is out of balance due to insulation breakdown of one wire. When detecting that a zero-phase voltage is generated between the terminals of the switch 3, the zero-phase voltage detection circuit 8 outputs a control signal for turning on the switch 3 to the switch control circuit 7.

Next, the operation of the earth leakage breaker control device 4 will be described. Wires R, S, T of ungrounded load-side circuit 41
When no ground fault has occurred, the switch 3 is off because no zero-phase voltage is generated between the terminals of the switch 3. When the switch 3 is off, the ground capacitors C1 to C3 are cut off from the ground electrode Ed. When the grounding capacitors C1 to C3 and the ground electrode Ed are cut off, the high-frequency leakage current 17 (FIG. 8) generated from the load 5 such as an inverter connected to the load-side electric circuit 41 Does not flow to As described above, when no ground fault has occurred in each of the phase wires R, S, and T of the ungrounded load-side circuit 41, the high-frequency leakage current 17 is
Since the current does not flow to 0, for example, the electronic device 6 and the like connected in parallel with the load 5 rarely cause noise disturbance. On the other hand, if one wire of the ungrounded load-side electric circuit 41 is broken down and grounded in a conduit grounded to the ground electrode Ed, the three-phase voltage is out of balance and a zero-phase voltage is applied between the terminals of the switch 3. Voltage is generated. When detecting the zero-phase voltage generated between the terminals of the switch 3, the zero-phase voltage detection circuit 8 outputs a control signal to the switch control circuit 7. When the control signal is input, the switch control circuit 7 turns on the switch 3 and connects the common connection part of the ground capacitors C1 to C3 to the ground electrode Ed. That is, the grounding capacitor C is connected between the electric wires R, S, T of each phase of the ungrounded power supply side electric circuit 40 and the grounding pole Ed.
1 to C3 are input. Thereby, the earth leakage breaker ELC
The current required to operate B2 flows, and the earth leakage breaker E
LCB2 performs a shutoff operation.

The switch control circuit 7 turns on the switch 3 for a predetermined time T and then turns off. This time T is
For example, it is set to 0.2 seconds when the earth leakage breaker ELCB2 is a high-speed earth leakage breaker, 3 seconds when it is a time-delayed earth leakage breaker, and 0.5 seconds when it is an anti-timed earth leakage breaker. This time T can be changed as appropriate.

In the first embodiment described above, the impedance circuit constituted by the grounding capacitors C1 to C3 is used as the operating current compensating circuit of the earth leakage breaker ELCB2, but is constituted by a resistor, a reactor and the like. An impedance circuit can also be used.

Next, a second embodiment of the present invention is shown in FIG. In the second embodiment, the impedance circuit in the first embodiment is configured by a transformer GPT and a resistor R2. As shown in FIG. 2, one terminal of the primary windings W1r, W1s, W1t of the grounding transformer GPT is connected to the electric wires R, S, T of each phase of the ungrounded power supply side electric circuit 40. ing. The other terminals of the primary windings W1r, W1s, W1t of the grounding transformer GPT are commonly connected and star-connected, and the neutral point N1 is grounded to the ground pole Ed. The secondary windings W2r, W2s, W2t of the grounding transformer GPT are connected in series, and
A resistor R2 and a switch 9 are connected in series between the open terminal of the secondary winding W2r and the open terminal of W2t.

The switch 9 is turned on and off by the earth leakage breaker control device 4 having the same configuration as that of the first embodiment. The zero-phase voltage detection circuit in the earth leakage breaker control device 4 is configured to detect a voltage generated between both terminals of the switch 9 when the switch 9 is turned off, that is, any one of the wires R, S, and T of the ungrounded load-side electric circuit 41. When a zero-phase voltage generated between both terminals of the switch 9 is detected when a crab ground fault occurs,
A control signal for turning on the switch 9 is output to the switch control circuit 7.

Next, the operation of the earth leakage breaker control device 4 according to the second embodiment will be described. Load side electric circuit 41
If no ground fault has occurred on the electric wires R, S, T
Switch 9 is off. When switch 9 is off,
Primary windings W1r, W1s, W1 of grounding transformer GPT
The impedance of t is higher than when switch 9 is on. Therefore, the high-frequency leakage current generated from the load 5 such as an inverter connected to the load-side electric circuit 41 does not easily flow through the power-supply-side electric circuit 40. Therefore, an electronic device or the like connected in parallel with the load 5 does not cause noise interference. on the other hand,
When the electric wire T of the load-side electric circuit 41 is broken down and grounded to the electric wire tube grounded to the ground electrode Ed, the electric wire T, the electric wire tube,
A ground fault current flows to the neutral point N1 of the primary windings W1r, W1s, W1t of the grounding transformer GPT via a ground wire and a ground pole Ed connected to the conduit tube. At this time, since the switch 9 is off, the primary winding W1 of the ground transformer GPT is turned off.
The impedances of r, W1s, and W1t are high. Therefore, the primary winding W of the ground transformer GPT
No current that operates the earth leakage breaker ELCB2 flows from 1r, W1s, W1t to the power supply side electric circuit 40. Further, when the three-phase voltage is out of balance due to the insulation breakdown of the wire T, a zero-phase voltage is generated at both ends of the switch 9 connected to the secondary winding of the ground transformer GPT.

When detecting the zero-phase voltage generated between both terminals of the switch 9, the zero-phase voltage detection circuit 8 outputs a control signal to the switch control circuit 7 to turn on the switch 9. When the switch 9 is turned on, the grounding transformer GPT 1
The impedance of the secondary windings W1r, W1s, W1t decreases, and the primary windings W1r, W1 of the grounding transformer GPT are reduced.
A current for operating the earth leakage breaker ELCB2 flows through s and W1t. Thereby, the earth leakage breaker ELCB2 performs a breaking operation. The resistance value of the grounding resistor R2 is set to a value at which a current that can reliably operate the earth leakage breaker ELCB1 via the primary windings W1r, W1s, W1t of the grounding transformer GPT flows. . Also, a grounding resistor R2
Instead, a capacitor, a reactor, or the like may be used.

Next, a third embodiment of the present invention is shown in FIG. Low-voltage side winding Tr of three-phase three-wire high-low voltage transformer Tr2
In order to prevent the 2S and the high-voltage side winding Tr2M from touching each other due to dielectric breakdown or the like and applying a high voltage to the low-voltage side,
In the third embodiment, the contact prevention plate 21 is provided between the low-voltage side winding Tr2S and the high-voltage side winding Tr2M. In the present embodiment, the contact prevention plate 21 is connected to the ground electrode Eb. The ground terminal of the load 5 is connected to the ground pole Ed. Also, in order to prevent the low-voltage side winding Tr1S and the high-voltage side winding Tr1M of the single-phase three-wire high-low voltage transformer Tr1 from touching each other due to dielectric breakdown or the like and applying a high voltage to the low-voltage side, In the third embodiment, the contact prevention plate 22 is provided between the low-voltage side winding Tr1S and the high-voltage side winding Tr1M.
In the present embodiment, the contact prevention plate 22 is connected to the ground electrode Eb.

As described above, when the touch prevention plate 21 is provided in the three-phase three-wire high-low voltage transformer Tr2, the low-voltage side electric circuit is in the non-ground state as in the first embodiment. Therefore,
In order to compensate the operating current of the earth leakage breaker ELCB2, it is necessary to connect the power supply side electric circuit 40 of the earth leakage breaker ELCB2 to the ground pole Ed via the grounding capacitors C1 to C3. Also in this case, there is a possibility that a problem may occur due to the sneak of the high-frequency leakage current 17 as in the first embodiment. Therefore, also in the present embodiment, as shown in FIG. 3, the switch 3 which is an electric circuit opening / closing means is provided between the grounding capacitors C1 to C3 and the grounding electrode Ed, and the earth leakage cutoff for controlling ON / OFF of the switch 3 is provided. The device controller 4 is provided. The configuration and operation of the earth leakage breaker control device 4 are as follows.
Since it is the same as the embodiment, the description is omitted. Further, the grounding impedance circuit may be the grounding transformer GPT shown in FIG.

Next, a fourth embodiment of the present invention is shown in FIG. In the fourth embodiment, the low-voltage-side ground terminal N of the single-phase three-wire high-low voltage transformer Tr1 and the low-voltage ground terminal TE of the three-phase three-wire high-low voltage transformer Tr2 are connected to the ground electrode Eb (for example, (Class B ground). A transformer Tr3 is provided on the low-voltage side electric circuit of the three-phase three-wire high-low voltage transformer Tr2.

If the low-voltage ground terminal N of the single-phase three-wire high-low voltage transformer Tr1 and the low-voltage ground terminal TE of the three-phase three-wire high-low voltage transformer Tr2 are always grounded, the above-described high-frequency leakage will occur. There is a possibility that a problem may occur due to the current 12 (FIG. 5), the ground fault current 14 (FIG. 6), and the constant leakage current 16 (FIG. 7). Therefore, in order to prevent these problems, in the fourth embodiment, a transformer Tr3 is provided on the low-voltage side electric circuit of the three-phase three-wire high-low voltage transformer Tr2. Since the electric circuit is insulated by the transformer Tr3, the above problem can be prevented. When the transformer Tr3 is provided, as in the first embodiment, the low-voltage side electric circuit is in a non-ground state. Therefore, in order to compensate for the operating current of the earth leakage breaker ELCB2, it is necessary to connect the power supply side electric circuit 40 of the earth leakage breaker ELCB2 to the ground pole Ed via the grounding capacitors C1 to C3. Also in this case, there is a possibility that a problem may occur due to the sneak of the high-frequency leakage current 17 as in the first embodiment. Therefore, also in the present embodiment, as shown in FIG.
A switch 3 which is an electric circuit opening / closing means is provided between the switch 3 and the switch d, and an earth leakage breaker control device 4 for controlling ON / OFF of the switch 3 is provided. The configuration and operation of the earth leakage breaker control device 4 are the same as those of the first embodiment, and therefore the description is omitted. Also,
The grounding impedance circuit may be the grounding transformer GPT shown in FIG.

In the first to fourth embodiments, the single grounding method in which the ground electrode Eb and the ground electrode Ed are separately provided is used. However, a common grounding method in which a common ground electrode is provided may be used. If a common grounding method is used, even if there is a lightning strike in the building, a potential difference between the grounding poles does not occur due to the lightning current, so that it is possible to prevent dielectric breakdown of the electronic device due to the lightning current. Also, since there is one grounding pole, the work of grounding work is also easy.

In the first and second embodiments, the ground terminal N of the low-voltage side electric circuit of the high-low voltage transformer is used as the grounding method.
And TE are grounded to the ground electrode Eb via the ground potential suppression devices 1A and 1B. In the fourth embodiment, the ground terminals N and TE are directly grounded to the ground electrode Eb. Third Embodiment In the above, a method in which the contact prevention plates 21 and 22 are grounded to the ground electrode Eb is used, but various grounding methods can be used. Further, various grounding methods can be combined. Further, the present invention can be used for at least one power transmission and distribution circuit requiring grounding.

In the first and second embodiments, the ground potential suppressing devices 1A and 1B are composed of the arrester Zn, the triac T, the varistor Znt, and the capacitor Co. It is not limited, and can be configured by various constituent elements. Further, in the first to fourth embodiments, the impedance circuit and the circuit
Although provided on the electric circuit on the side of the phase three-wire high-low voltage transformer Tr2, it may be provided on the electric circuit on the side of the single-phase three-wire high-low voltage transformer Tr1 or on both sides. Further, the high voltage side of the high / low voltage transformer connected to the power supply side may be an extra high voltage of 7000V or more. Also, the low voltage distribution grounding device has been described,
The present invention can be applied to various grounding type power transmission and distribution devices.

[0037]

As described above, the use of the power transmission / distribution device according to any one of claims 1 to 7 can reduce the influence of the sneak path of the high-frequency leakage current and ensure that the leakage breaker operates. Now you can do it. Thereby, safety was improved.

[0038]

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an embodiment of a power transmission and distribution device of the present invention.

FIG. 2 is a schematic diagram of an embodiment of the power transmission and distribution device of the present invention.

FIG. 3 is a schematic diagram of an embodiment of the power transmission and distribution device of the present invention.

FIG. 4 is a schematic diagram of an embodiment of a power transmission and distribution device of the present invention.

FIG. 5 is an explanatory diagram showing a problem.

FIG. 6 is an explanatory diagram showing a problem.

FIG. 7 is an explanatory diagram showing a problem.

FIG. 8 is an explanatory diagram showing an example of a countermeasure for a problem.

FIG. 9 is an explanatory diagram showing a conventional wiring diagram.

[Explanation of symbols]

 Reference Signs List 1A, 1B Ground potential suppression device 3 Switch 4 Earth leakage breaker control device 5 Load 6 Electronic device Tr1 Single-phase three-wire high-low voltage transformer Tr2 Three-phase three-wire high-low voltage transformer Tr3 Transformer ELCB1,2 Earth leakage breaker C1 To C3 Grounding capacitor Eb Grounding pole Ed Grounding pole GPT Grounding transformer 21, 22 Contact prevention plate 40 Power supply circuit of earth leakage breaker 41 Load circuit of earth leakage breaker

Claims (7)

[Claims] At least one power transmission / distribution circuit provided with an earth leakage breaker, and at least one power transmission / distribution circuit between a ground terminal and a first ground electrode of a power supply side electric circuit on a power supply side of the earth leakage breaker. A ground potential suppressing device, an impedance circuit and switching means provided between a power supply side of the at least one power transmission / distribution circuit and a power supply side of the leakage breaker and a second grounding pole, and switching means And control means for controlling the ground potential of the power transmission and distribution line when the voltage of at least one of the power transmission and distribution lines is equal to or higher than a set value.
The control means controls the switching means when detecting that at least one power transmission / distribution circuit is grounded, and connects the impedance circuit between the power transmission / distribution path and the second ground electrode. Power transmission and distribution equipment. 2. The power transmission and distribution device according to claim 1, wherein the at least one power transmission and distribution line includes a high / low voltage transformer on a power supply side. 3. At least one transmission / distribution circuit provided with an earth leakage breaker, a high / low voltage transformer provided on a power supply side of at least one transmission / distribution circuit, and a high / low voltage grounded to a first ground electrode. A contact prevention plate of a transformer, a power supply side power supply side of at least one power transmission and distribution line, a power supply side of the power supply side from the earth leakage breaker,
An impedance circuit and an opening / closing means provided between the grounding electrode and a control means for controlling the opening / closing means, wherein the control means switches the opening / closing means when detecting that at least one power transmission / distribution circuit has a ground fault. A power transmission / distribution device, wherein the impedance circuit is controlled to be connected between the power transmission / distribution circuit and the second ground electrode. 4. An earth leakage breaker for at least one transmission / distribution circuit provided with an earth leakage breaker, a high / low voltage transformer provided on a power supply side of the at least one transmission / distribution circuit, and a low voltage side electric circuit of the high / low voltage transformer. A transformer provided between the transformer, an impedance circuit and switching means provided between the secondary side electric circuit of the transformer and the second ground electrode, and control means for controlling the switching means, The ground terminal of the circuit between the low-voltage side of the high-low voltage transformer and the transformer is connected to the first ground electrode, and the control means switches the switching means when detecting that at least one power transmission and distribution circuit has a ground fault. A power transmission and distribution device, wherein the impedance circuit is controlled to be connected between a secondary circuit of a transformer and a second ground electrode. 5. The power transmission and distribution device according to claim 1, wherein the impedance circuit includes a capacitor,
Constituted by at least one of a resistor or a reactor,
The power transmission and distribution device, wherein the switching means is connected between the impedance circuit and the second ground electrode. 6. The power transmission and distribution device according to claim 1, wherein the impedance circuit has a transformer, and the switching means includes a secondary winding of the transformer and a second ground. A power transmission / distribution device provided between the poles. 7. The power transmission and distribution device according to claim 1, wherein the first ground electrode and the second ground electrode are the same ground electrode.