JPH05284636A - Grounding detector for distribution facility - Google Patents

Abstract

PURPOSE:To detect the grounding accident by the trouble of a surge absorber for absorbing switching surge of a feeder breaker separately for each feeder. CONSTITUTION:A cable 8, which supplies power from a feeder breaker 5 to load, and the earth 7 of a surge absorber 6 are put together and are passed through a zero-phase current transformer 9 for grounding current detection. Hereby, the grounding accident of each surge absorber of a feeder can be detected, so the early discovery of an accident and the stable power supply can be materialized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground fault detection device for power distribution equipment for detecting ground faults such as main transformer busbars and feeders in power distribution equipment.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional ground fault detecting device for power distribution equipment. In the figure, 1 is a distribution line communicating with a power source, 2 is a main transformer arranged on the distribution line 1, and 3 is a main transformer. Is a main transformer secondary circuit breaker, 4 is a secondary voltage bus of the main transformer 2, 5
Is a feeder breaker connected to the load, 6 is a surge absorber that absorbs the switching surge of the feeder breaker 5, 7 is the ground wire of the surge absorber 6, and 8 is power from the feeder breaker 5 to the load. An electric wire to be supplied, 9 is a zero-phase current transformer as a current transformer for detecting a ground fault current.

Numeral 10 is a grounding transformer in which three single-phase transformers are generally used, the primary side of which is connected in a star shape and the neutral point is grounded,
Reference numeral 11 is a ground wire of the ground transformer 10, and 12 is a ground transformer 10.
The ground fault direction relay which operates by the ground fault voltage generated in 1 and the detection of the zero phase current in the zero phase current transformer 9, 13 is the ground transformer 1
It is a ground fault overvoltage relay that operates with a ground fault voltage generated at zero.

Next, the operation will be described. When the surge absorber 6 fails and a ground fault occurs via the ground wire 7 of the surge absorber 6, a ground fault current flows as indicated by I ₀ . This ground fault current I ₀ flows to the primary side of the grounding transformer 10 via the grounding wire 11 at the neutral point of the grounding transformer 10.
Further, since the secondary side is connected in an open triangle, a ground fault voltage V ₀ is generated by the secondary side I ₀ . By detecting this V ₀ and operating the ground fault overvoltage relay 13, the failure display indicates that a ground fault has occurred at any point on the load side of the main transformer secondary breaker 3. Ground fault overvoltage relay 13
As described above, the ground fault detection by the operation of (1) operates also at any point on the load side of the main transformer secondary side circuit breaker 3, that is, at the ground fault accident due to the failure of the surge absorbing device 6.

When it takes a long time to find and remove a faulty part, the main transformer secondary breaker 3 is disconnected to disconnect the ground fault point from the distribution system to protect the distribution equipment and the power supply. In some cases. Therefore, the ground fault of the feeder may disconnect the entire distribution system from the power source, resulting in a total power failure.

[0006]

Since the conventional ground fault detection device for power distribution equipment is constructed as described above, the ground fault detection device provided on the load side of the feeder breaker 5 causes a ground fault. It is not possible to select and detect a faulty accident for each feeder circuit breaker 5, and the main transformer secondary circuit breaker 3 that connects to the power supply side is disconnected due to an accident of each feeder cable, which impairs stable power supply. There was a problem that

The present invention has been made in order to solve the above-mentioned problems, and it is possible to selectively detect a ground fault accident due to a failure of a surge absorber for each feeder.
An object of the present invention is to obtain a ground fault detection device for power distribution equipment, which can disconnect the feeder breaker corresponding to the surge absorber in this ground fault accident.

[0008]

A ground fault detection device for power distribution equipment according to the present invention provides a ground wire of a surge absorber that absorbs a surge due to opening and closing of a feeder breaker, and supplies a power from the feeder breaker to a load. The grounding current detection current transformer is passed along with the electric wire to be grounded.

[0009]

The ground fault detecting device for power distribution equipment according to the present invention is
A ground fault occurs due to a failure of the surge absorber because the ground wire of the surge absorber is combined with the wire that supplies power from the feeder breaker to the load and passed through the current transformer for ground fault current detection. In this case, the ground fault current detecting current transformer detects the ground fault current passing through the ground line of the surge absorber.

[0010]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as those in FIG. In the first embodiment, as shown in FIG. 1, the ground wire 7 of the surge absorber 6 is combined with the electric wire 8 that supplies electric power from the feeder breaker 5 to the load, and a zero-phase current change for ground fault detection. The ground wire 7 is grounded by passing through the container 9.

Next, the operation will be described. When the surge absorber 6 breaks down and a ground fault occurs via the ground line 7 of the surge absorber 6, a ground fault current flows through the ground line 7 through a route indicated by I ₀₁ . Therefore, since the ground fault current passes through the zero-phase current transformer 9, the zero-phase current transformer 9 can detect the ground fault current of the ground line 7. Further, this ground fault current I ₀₁ flows to the primary side of the ground transformer 10 via the ground wire 11 at the neutral point of the ground transformer 10, so that the ground fault voltage V _{01 is} applied to the secondary side connected in an open triangle. Occurs. This V ₀₁ and I ₀₁
Is detected by the ground fault direction relay 12, it is possible to make a limited judgment on the fault range when the ground side fault occurs on the load side of the feeder cable breaker 5 when the load side is seen from the power source.

According to the above, the ground fault 7 caused by the failure of the surge absorbing device 6 due to the opening / closing of the feeder breaker 5 is passed through the ground wire 7 through the zero-phase current transformer 9 as described above. It becomes possible to selectively detect each electric wire and disconnect it from the distribution system in units of the feeder. Therefore, the main transformer secondary breaker 3 does not need to separate the ground fault point from the distribution system, and the main power source is alive, so that stable power supply can be achieved.

Embodiment 2. Although the zero-phase current transformer 9 is shown as the ground-fault detecting current transformer in the first embodiment, the first embodiment is shown in FIG. Similar effects can be obtained by changing as shown. In FIG. 2, 1 to 8, 10 and 11 are the same devices as those in FIGS. 9a is a current transformer that detects the current flowing through the feeder breaker 5, 14 is an overcurrent relay, and 15 is a ground fault overcurrent relay.
It is connected to a.

FIG. 3 shows a case where FIG. 2 is simply made into a three-line diagram. In FIG. 3, for example, if the R-phase surge absorber 6 fails and a ground fault occurs, 3I ₀ is connected to the R-phase ground wire 7.
The ground-fault current of (3) flows, the R-phase current transformer 9a detects this ground-fault current, and a current of 3I ₀ flows to the ground-fault overcurrent relay 15, so that a ground-fault accident can be detected. The same applies to failures in the S and T phases.

In the first and second embodiments, the case where the power source side is the main transformer 2 is shown. However, it may be a generator, and the same effect as in the first and second embodiments is obtained. Also, the case where the grounding transformer 10 is provided on the bus bar 4 on the secondary side of the main transformer is shown, but even when the secondary winding of the main transformer is star-connected and its neutral point is grounded. Good. Further, although the ground fault direction relay 12 is shown as the ground fault detection relay, a ground fault overcurrent relay may be used depending on the neutral point grounding method, and even in that case, the same effect as in the above-described first and second embodiments. Play.

[0016]

As described above, according to the present invention, the grounding wire of the surge absorber and the wire from the feeder breaker are combined so that they pass through the ground fault current detecting current transformer. , A ground fault accident due to a failure of the surge absorbing device provided to absorb the surge due to the opening and closing of the feeder breaker can also be detected by the ground fault direction relay that detects the ground fault of the feeder wire. By this, there is an effect that the failure of the surge absorber can be selectively detected for each feeder.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a ground fault detection device for power distribution equipment according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the same device.

FIG. 3 is a configuration diagram showing a case where the apparatus according to another embodiment is a three-wire system.

FIG. 4 is a configuration diagram showing a conventional ground fault detection device for power distribution equipment.

[Explanation of symbols]

 4 Bus bar 5 Feeder breaker 6 Surge absorber 7 Ground wire 8 Wire 9 Zero-phase current transformer (current transformer for ground fault current detection) 9a Current transformer (current transformer for ground fault current detection)

Claims (1)

[Claims] 1. A feeder breaker connected to a bus bar, an electric wire for supplying electric power from the feeder breaker to a load, a surge absorber for absorbing switching surge of the feeder breaker, and the surge absorber. A ground fault detection device for power distribution equipment, comprising: a ground line of a device; and a current transformer for detecting a ground fault current that passes the electric wire and the ground line together.