JPS584415B2 - How to get started - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum defect detection method for early detection of vacuum defects in a vacuum switchgear.

Vacuum switchgears are often used on high-voltage distribution lines for purposes such as limiting power outage sections, supplying from other routes in the event of an accident, and maintaining and inspecting each section of the distribution circuit.This vacuum switchgear is housed in equipment. The power distribution circuit is connected and disconnected using the contacts of the vacuum valve.

When the vacuum switchgear is open, the power supply side pole of the vacuum valve contact carries the distribution voltage, and the load side pole usually has a capacitance to ground, which is greater than the capacitance of the vacuum valve contact gap. Since it is also large, it has a ground potential.

Note that the power supply side is usually called the live line side, and the load side is called the dead line side.

Therefore, the ground voltage of the distribution voltage is applied to the contact gap of the vacuum valve.

If there is a defect in the airtightness of the vacuum valve and the pressure inside the vacuum valve increases, the insulation at the contact gap will deteriorate and the voltage to the ground voltage of the distribution voltage will be discharged and the voltage will be applied to the dead line side line which should be dead. This poses a risk of electric shock to workers performing maintenance and inspection in the power outage section.

In order to prevent such accidents, it is necessary to detect defects in the vacuum valve of the switchgear, and one method for this detection is as follows.

In this method, a pulse generator applies a pulse to one phase on the dead line side of the switchgear, and if a discharge occurs, the meter of the pulse generator detects it.

However, even if a pulse is applied to any one phase and a discharge is detected, if other devices such as arresters or insulators are connected to this distribution line, it is impossible to determine if there is a defect in these devices and a discharge occurs. .

Also, if a transformer is connected, the pulses will circulate from one applied phase to the other phases through the windings, so if there is a discharge point somewhere in each phase, the discharge will be detected, making it difficult to detect a defective switch. There is a point.

Other methods for detecting grounding faults on distribution lines include applying a pulse to one phase of the distribution line and placing an antenna between the common ground wire and the distribution line to detect the fault point, or There is a method of detecting the grounding fault point by connecting a split current transformer to the common grounding wire.

However, these methods detect grounding failures of connected equipment such as arresters or insulators, and because the discharge of the vacuum valve of the switch does not have a current path to the ground, these methods detect defects in the vacuum pulp. Not suitable for detection.

Furthermore, in the case of a vacuum defect in a vacuum valve of a vacuum switchgear, there is a phenomenon in which the vacuum level of the defective valve temporarily improves as the number of discharges and current due to the applied pulse increases. This is called the up effect.

Because of this clean-up effect, if a discharge occurs during the first application and this discharge is not detected, there is a possibility that the insulation of the vacuum pulp will recover and no discharge will occur even if the pulse is applied again. , it is difficult to hope for complete discharge detection.

In this way, if a pulse is applied to one phase of the distribution line on the dead line side of the switchgear, it is as if the pulse was applied to all three phases at once through the winding of the transformer connected to the line, as described above, and if a discharge is detected. However, there are some defects that make it unclear whether it is a vacuum valve, other arrester, or insulator.

An object of the present invention is to apply a test voltage higher than the standard working voltage to a vacuum valve housed in a vacuum switchgear mounted on a column, for example, to detect a defective vacuum valve in the early stage of vacuum deterioration. An object of the present invention is to provide a vacuum defect detection method.

The present invention will be described below with reference to embodiments shown in FIGS. 1 to 4.

As shown in Fig. 1, the high voltage distribution line is connected to a vacuum switchgear 101.
and 102, and when both are open, section B is a dead line, and sections A and C are live lines.

In the actual distribution line, equipment such as an arrester 31 with a built-in gap, an insulator 32, and a pole transformer 33 are installed in this section.

The opening/closing device 101 includes vacuum valves 11, 12, and 13, and the opening/closing device 102 includes vacuum valves 21, 22, and 23.

In Figure 2, a zero-phase current transformer 36 is inserted into each of the R, S, and T phases in Figure 1, an ammeter 37 is connected, and the current transformer 3
Reference numeral 6 has a structure in which the iron core at one end can be opened and the electric wires of the R, S, and T phases can be passed through.

A pulse generator 401 shown in FIG. 3 is connected to the power distribution line by a terminal 40a through a switch 40, and the pulse generator 401 has the ability to repeatedly generate pulses at selected intervals, such as every 5 seconds. ing.

Regarding this generator 401, 41a, 4lb and 42a
, 42b is a wave front adjustment capacitor and resistor, 43 is a wave tail adjustment resistor, 44 is a power supply capacitor, 45 is a control switch or control gap, 46 is a protection resistor for the power supply capacitor 44 and the rectifier 47, and the rectifier 47
can change the polarity of the charging voltage of the power supply capacitor 44, 48 is a high voltage transformer, 49 is a voltage regulator, 50
numeral 51 is a mobile power source such as an automobile generator, numeral 51 is a discharge current detection circuit consisting of a resistor and an ammeter, and numeral 52 is a power supply circuit.

In Figure 1, positions 1, 2, 3, 4 indicated by two-dot chain lines
As shown in FIG. 2, indicates the position where a zero-phase current transformer (hereinafter abbreviated as ZCT) is inserted in each of the three phases.

The procedure of the method for detecting a defective valve according to the present invention will be explained below.

(1) ZCT at position 4 near section B side of switchgear 102
and connect the connection terminal 40 of the pulse generator 401 in Fig. 3.
A is connected to one of the RST phases, for example, the R phase as shown in FIG. 1, and a pulse is applied.

In this case, a pulse is applied to one phase, but as described above, the pulse wraps around to other phases by the winding of the transformer 33, so it is the same as when a pulse is applied to three phases at once.

Further, pulses may be applied in three phases sequentially, or pulses may be applied in three phases simultaneously.

If the ammeter A of the ZCT swings, it means that there is a defective valve in the switching device 102.

That is, if a defective valve exists in the switch 102, as shown in FIG. Current flows.

This current flows through the ZCT installed near the switchgear 102 in section B.
is detected, and the pointer of the ammeter 37 swings.

Since these defective valves are housed in the same case, the device must be removed even if there is a defective valve in any phase, and at that time the entire device is replaced.

ii If the ZCT ammeter does not swing, switchgear 1
The 02 three-phase vacuum valve is normal.

1 [If ZCT is inserted at both ends of the IB section, that is, at positions 1 and 4, and a pulse is applied, the switchgear 101,
102 defects can be detected simultaneously, and a defective valve can be detected by the first application.

(2) By inserting a ZCT at position 1 and applying a pulse, it is possible to determine whether the opening/closing device 101 is good or not.

That is, if there is a defective valve, current will flow as shown by the arrow in FIG. 6, so if the ZCT ammeter 37 swings, the switching device 101 should be replaced, and if it does not swing, it is normal.

(3) When the ZCT is inserted at position 2 and a pulse is applied, if the ammeter swings, it means that the arrester 31 has discharged, but it is unclear which phase.

However, if it is detected with ZCT inserted for each phase. The discharged phase can be determined.

Also, if the ammeter does not swing, the arrester 31 is normal.

(4) When the ZCT is inserted at position 3 and a pulse is applied, if the ammeter swings, there is a defect between positions 2 and 3, that is, insulator 32.

Also, if the ammeter does not swing, the paddle 32 has no selection.

In this way, defects including the vacuum switchgear 101, 102 and the equipment therebetween can be detected.

Figure 4 shows a three-phase zero-phase current transformer 38 connected to an ammeter 37. This current transformer may be of a split type, or it may have a structure in which a part of the iron core is opened and the current transformer is inserted into the distribution line. However, the second
It has the same effect as the ZCT shown in the figure.

As described above, according to the present invention, 3 on the dead line side of the distribution line of the vacuum switchgear
By inserting a zero-phase current transformer for all phases, it is possible to detect a discharge even if a vacuum failure occurs in the vacuum valve of any phase and a discharge is caused by the first pulse application.

Therefore, it is possible to provide a vacuum defect detection method for a vacuum switchgear that is not affected by the clean amplifier effect described above and does not cause failure in detection of defective valves.

[Brief explanation of drawings]

Figure 1 is a circuit diagram for explaining the principle of the method for detecting vacuum failures in vacuum switchgear according to the present invention, and Figure 2 is the configuration of a three-phase zero-phase current transformer for detecting vacuum failures according to the present invention. 3 is an electric circuit configuration diagram of a pulse generator used in the present invention, FIG. 4 is a configuration diagram showing another embodiment of a three-phase collective zero-phase current transformer used in the present invention, and FIG. and FIG. 6 is a partial circuit diagram illustrating the flow of current through a defective valve. 101, 102... Vacuum switchgear, 36, 38...
Zero-phase current transformer, 401...pulse generator.

Claims (1)

[Claims] 1 One side of the vacuum switchgear is a live line, the other side is a dead line, and a zero-phase current transformer equipped with an ammeter is inserted for all three phases near the vacuum switchgear on the dead line side. A method for detecting a vacuum defect in a vacuum switchgear, characterized in that a pulse is applied to each phase on the dead line side, and a discharge current of the vacuum switchgear is detected by an ammeter of the zero-phase current transformer.