JPH07236226A - Ground protector - Google Patents

Abstract

PURPOSE:To detect ground fault positively by winding the detection windings of first and second ground fault detectors in same direction, connecting the windings in series with a switch, connecting the series circuit in parallel with a ground relay. CONSTITUTION:Upon occurrence of a ground fault at point A on the first bus side of a bus tie line 9, a ground fault current flows through a circuit of the neutral of a transformer 2 - a connecting line 11 - a ground fault detector 19 - the earth 12 - a ground fault point A - a bus tie line 9 - a first bus 1 and through a circuit of the neutral of transformer 6 for the second bus 5 - the connecting line 11 - a ground fault detector 20 - the earth line 12 - the ground fault point A - the bus tie line 9 - the second bus 5. A ground fault voltage is induced in the ground fault detectors 19, 20 and applied to a load 22. Consequently, a ground relay 21 functions to open a bus tie circuit breaker 10 based on an open command signal at an output terminal 21a thus operating the first and second buses independently. This constitution detects a ground fault positively through simple circuitry and minimizes the power interruption range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention connects an AC power source and a load via one of a plurality of busbars connected to each other via a busbar breaker so that one of the busbars has a ground fault. The present invention relates to a ground fault protective equipment suitable for protecting the other bus bar when it occurs.

[0002]

2. Description of the Related Art In a power system, a plurality of busbars are connected via a busbar breaker so that power is supplied from one busbar to another busbar, and even if the power supply of one busbar fails, Power can be supplied from the power source of the bus bar to the load of each bus bar. When a ground fault or the like occurs in each bus bar, the circuit breaker arranged for each bus bar is tripped to protect the system. However, if each busbar is connected with a busbar breaker, if a ground fault occurs on one busbar, a ground fault current will flow through each busbar, and the circuit breaker on each busbar will trip and power to the load on a healthy busbar. Is no longer supplied,
There was a problem that the power outage range was wide. For this reason,
In the conventional ground fault protection device, as shown in FIG. 3, a first busbar 1 connecting a transformer 2, a circuit breaker 3 and a load 4 and a second busbar 5 connecting a transformer 6, a circuit breaker 7 and a load 8 are provided. It is provided. A busbar communication circuit breaker 10 is inserted in a busbar communication line 9 connecting the output side of the circuit breaker of the first busbar and the output side of the circuit breaker of the second busbar. First Bus Transformer 2 and Second Bus Transformer 6
Are connected by Δ-Y, the secondary side neutral points of the respective transformers are connected by a connecting line 11, and the middle thereof is grounded via a grounding line 12. Grounds 13 and 14 are provided between the connection point where the ground wire 12 is connected to the connection line 11 and the neutral point of the transformer 2 of the first busbar and between the neutral point of the transformer 6 of the second busbar. A ground fault detector, 15 is a ground fault detector attached to the ground wire 12,
Reference numerals 17 and 18 denote ground fault relays connected to the respective ground fault detectors. In the ground fault protection device configured in this way,
To detect a ground fault, the ground fault relay 18 connected to the ground fault detector 15 provided on the ground line 12 opens the bus bar communication breaker 10 and then the ground fault detector provided on the connection line 11 on the first bus line 1 side. 1
3 of ground fault relay 16 and ground fault detector 1 provided on ground wire 12
AND condition with the ground fault relay 18 connected to 5 or the ground fault detector 17 of the ground fault detector 14 provided on the connection line 11 on the second bus 5 side and the ground fault detector 15 provided on the ground line 11 The AND condition with the ground fault relay 18 was used to determine whether the ground fault occurred on the first bus or the ground fault on the second bus.

[0003]

However, in the prior art, the neutral point of the transformer 2 of the first busbar 1 passes through the connecting line 11, the ground fault detector 13 passes through the connecting line, and the ground fault detector 14 passes. Passing through the neutral point of the transformer 6 of the second bus bar 5, the circuit breaker 7, the bus bar communication line 9, the bus bar communication circuit breaker 10, and the circuit breaker 3 of the first bus bar 1.
A circulating current flows through the circuit passing through the neutral point of the transformer 2 through the ground and acts as a zero-phase current on the ground fault detectors 13 and 14, which has the drawback of increasing the setting of the ground fault relay. There is a drawback that the number of fault detectors and ground fault relays increases. An object of the present invention is to simplify the circuit configuration to reliably detect a ground fault and to minimize the power outage range due to the fault.

[0004]

In order to solve the above problems, the present invention provides a plurality of busbars for connecting an AC power source and a load via a circuit breaker, and supplies electric power from one busbar to the other busbar. A ground fault protection device that connects bus lines to each other through a bus line breaker so that they can be supplied, detects a ground fault current flowing through the bus line, and disconnects a bus line in which a ground fault has occurred from other bus lines. A first circuit breaker inserted in a first bus connecting the AC power supply and the first load; a second circuit breaker inserted in a second bus connecting the second AC power supply and the second load; First
The busbar connecting circuit breaker inserted in the busbar connecting line connecting the output side of the circuit breaker and the output side of the second circuit breaker, the first busbar and the second busbar were connected, and the intermediate portion was connected to the ground line. Between the connection line and the intermediate portion of the connection line connecting the ground line and the first busbar, and the second
The winding directions of the first ground fault detector and the second ground fault detector provided on the connecting line of the bus and the detection windings of the first ground fault detector and the second ground fault detector are set to the same direction. A ground fault detection circuit is provided, which is wound and connected in series to the switch, and those connected in parallel, and the connected both ends are connected to both ends of the load of the ground fault relay.

[0005]

By means of the above means, when a ground fault occurs during parallel operation, the bus line breaker of the bus line is opened, each bus line is switched to independent operation, and the ground fault detector connected to the connecting line is detected. The switch connected in series with the winding is opened and closed to detect whether the ground fault detector operates or does not operate, and the ground fault accident of the first bus or the ground fault of the second bus is detected. The circuit breaker for the bus that is being generated is opened.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a ground fault protection device. The same parts as those in FIG. 2 are designated by the same reference numerals and detailed description thereof will be omitted. Reference numerals 19 and 20 denote zeros provided between the connection point where the ground line 12 is connected to the connection line 11 and the neutral point of the transformer 2 of the first busbar, and between the neutral point of the transformer 6 of the second busbar. It is a ground fault detector such as a phase current transformer. The detection windings of the ground fault detector are wound so that the windings are in the same direction, and switches in which the switches 23 and 24 are connected in series are connected in parallel.
A ground fault detection circuit 25 is configured by connecting the connecting ends to both ends of the load 22 of the ground fault relay 21. 21a, 21b,
Reference numeral 21c is an output terminal provided on the ground fault relay, which is a ground fault detector 1
When 9 and 20 detect a ground fault, the ground fault relay operates to output an open circuit command signal to the busbar breaker 10 from the output terminal 21a. When the ground fault detector 19 detects a ground fault, the ground fault relay operates. Operates and outputs an open circuit command signal to breaker 3 Terminal 2
1a, and when the ground fault detector 20 detects a ground fault accident, the ground fault relay operates to output an open circuit command signal to the circuit breaker 7 from the output terminal 21b. In the ground fault protection device thus configured, the circuit breakers 3, 7, 10 for the first busbar 1, the second busbar 5 and the busbar connecting line 9 are closed from the state shown in FIG. Electric power is supplied from the two buses 5 to the loads 4 and 8 in parallel operation.
In this case, the circuit of the first busbar 1 passes from the transformer neutral point of the first busbar 1 through the connecting line 11 and the transformer neutral point of the second busbar 5 to the second busbar 5 through the busbar connecting line 9. Even if a circulating current flows through the circuit, the detection winding of the ground fault detector 19 and the detection winding of the ground fault detector 20 have the same winding direction, so the circulating current flowing through the load is in the opposite direction. The voltage generated across the load 22 is canceled and the ground fault relay 21 does not operate. Now, when a ground fault occurs at point A on the first busbar side of the busbar connecting line 9, a ground fault is detected by passing through the connecting line 11 from the neutral point of the transformer 2 of the first busbar 1 as shown in FIG. Circuit 19 through the grounding line 12 through the grounding line 12 to the first busbar 1 from the busbar connecting line 9 and the neutral point of the transformer 6 of the second busbar 5 through the connecting line 11 to the grounding fault. A ground fault current flows from the detector 20 through the ground line 12 to the circuit flowing from the ground fault point A to the second bus 5 from the bus connecting line 9 to induce a ground fault voltage in the ground fault detectors 19 and 20. It is applied to the load 22, the ground fault relay 21 operates, and the busbar connection breaker 10 is opened by the open circuit command signal of the output terminal 21a of the ground fault relay. When the busbar connecting circuit breaker is opened, the first busbar and the second busbar are each operated independently. In this state, when the switch 23 is opened and the switch 24 is closed, the detection winding of the ground fault detector 19 is opened and the first
The grounding fault of the busbar 1 is not detected, and the detection winding of the grounding fault detector 20 is closed. Therefore, in order to detect the grounding fault of the second busbar 5, the connection connected to the neutral point of the transformer 6 is made. Since the ground fault current does not flow through the circuit of the ground line through the line 11, the ground fault detector 20 provided in this circuit does not operate and outputs the open circuit command signal of the breaker 7 from the output terminal 21c of the ground fault relay 21. No output is made and it is detected that no ground fault has occurred on the second bus bar 5. Next, when the switch 23 is closed and the switch 24 is opened, the detection winding of the ground fault detector 20 does not detect the ground fault accident of the second bus bar 5, and the detection winding of the ground fault detector 19 is closed. Therefore, the ground fault current is flowing in the circuit of the ground line through the connection line 11 connected to the neutral point of the transformer 2, and the ground fault detector 19 provided in this circuit operates to operate the ground fault relay 21. Output terminal 21b
Outputs an open circuit command signal for the circuit breaker 3 to open the circuit breaker 3 of the first busbar where the ground fault has occurred. Although the transformers are connected to the first busbar and the second busbar in the embodiment shown in FIG. 1, a generator may be used, and switches 23 and 24 are provided in series with the detection windings of the ground fault detectors 19 and 20, respectively. , Ground fault detector 1
It may be provided on either one of the detection windings 9 and 20.

[0007]

As described above, according to the present invention, it is possible to simplify the circuit structure, reliably detect a ground fault, and minimize the power failure range due to the fault.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a ground fault protection device of the present invention.

FIG. 2 is a flowchart of the ground fault protection device of the present invention.

FIG. 3 is a circuit diagram of a conventional ground fault detection device.

[Explanation of symbols]

1 1st Bus 2 Transformer 3 Circuit Breaker 4 Load 5 2nd Bus 6 Transformer 7 Circuit Breaker 8 Load 9 Bus Bar Connecting Line 10 Bus Bar Connecting Circuit Breaker 11 Connection Line 12 Ground Line 19, 20 Ground Fault Detector 21 Ground Fault Relay 22
Burden 23, 24 Switch 25 Ground fault detection circuit

Claims (1)

[Claims] 1. A plurality of busbars for connecting an AC power source and a load via a breaker are provided, and the busbars are connected via a busbar breaker so that power can be supplied from one busbar to the other busbar. In a ground fault protection device that detects a ground fault current flowing in a bus and disconnects the bus in which a ground fault has occurred from another bus, it is inserted in a first bus connecting a first AC power supply and a first load. A first circuit breaker, a second circuit breaker inserted in a second busbar connecting the second AC power supply and the second load, an output side of the first circuit breaker and an output side of the second circuit breaker A busbar connecting circuit breaker inserted in the busbar connecting line connecting the first busbar and the second busbar;
A first ground-fault detector and a first ground-fault detector provided between the connecting line connecting the bus bar and the middle part to the ground line, and between the first bus bar and the middle part of the connecting line connecting the ground line and the second bus line. The ground fault detector of No. 2 and the detection windings of the first ground fault detector and the second ground fault detector are wound in the same direction and connected in series to the switch, and those connected in parallel. And a ground fault detection circuit having both connected ends connected to both ends of the load of the ground fault relay.