JP3346780B2 - Vacuum switch abnormality detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum switch abnormality detecting device , and more particularly, to a vacuum switch used in a gas insulated transformer or a load tap changer of a non-combustible transformer using non-combustible liquid. The present invention relates to a simple abnormality detection device .

[0002]

2. Description of the Related Art In recent years, substation facilities installed in places where the population is dense, such as underground shopping malls and high-rise buildings, have been considered in consideration of disaster prevention.
SF ₆ has come to equipment using (sulfur hexafluoride S) gas or the like is employed, this is no exception in the transformer, SF ₆ gas-insulated transformers and using SF ₆ gas, Non-combustible transformers using non-combustible liquids have begun to be adopted.

[0003] Accordingly, there is a demand for a device that can be used in such SF ₆ gas or non-combustible liquid as a load tap changer for voltage adjustment used in such a transformer built in. As such a device, there is a vacuum switch-type on-load tap changer using a vacuum switch in a current switching part. The vacuum switch used in this tap changer has a contact portion housed in a container and cuts off current while keeping the atmosphere in a vacuum state, and the cutoff performance is extremely good.

[0004] The prior art of the vacuum switch type load tap changer, its switching sequence, and a method of detecting an abnormality of the vacuum switch will be described with reference to FIGS. 7 to 9. First, in FIG. 7, W is a tap winding of a transformer, T is a tap, and TS1 and TS2 are tap windings W.
Is a tap selector for selecting a tap. Next, VS1 and VR1 are vacuum switches. Among them, the vacuum switch VS1 is connected in series with the tap selector TS1, and connected in parallel with the resistor R1.
It is connected in series with R1.

Similarly, VS2 and VR2 are vacuum switches, of which the vacuum switch VS2 is a tap selector T
It is connected in series with S2, connected in parallel with resistor R2, and further connected in series with vacuum switch VR2. The vacuum switch VR1 and the vacuum switch VR2 are connected in series, and their connection point is a neutral point or a line end N.

Next, the tap switching operation will be described.
First, in FIG. 7, the vacuum switch VS1 and the vacuum switch VR1 are closed, and the current flows from the tap winding W through the tap selector TS1, and passes through the vacuum switch VS1 and the vacuum switch VR1 to the neutral point or the line. It flows to the end N.

Next, the operation when the current moves to the tap selector TS2 will be described. The operation at this time is shown in FIG.
When the vacuum switch VS1 is opened in the first step as shown in the figure, current flows from the tap winding W through the tap selector TS1 and the resistor R1. And flows to the neutral point or the line end N.

Next, in a second step, a vacuum switch VR2
, The current flow is doubled as follows. That is, one is from the tap winding W to the neutral point or the line end N via the tap selector TS1, the resistor R1 and the vacuum switch VR1, and the other is the tap winding W from the tap selector TS2, the resistor R2 and The current flows to the neutral point or the line end N via the vacuum switch VR2. Further, in this case, the taps are short-circuited via the resistors R1 and R2, and a circulating current flows through the resistor R1, the vacuum switches VR1, VR2, and the resistor R2 due to the potential difference of one tap.

Next, when the vacuum switch VR1 is opened in the third step, the current flows from the tap winding W to the tap selector TS2,
The current flows to the neutral point or the line end N through the resistor R2 and the vacuum switch VR2.

When the vacuum switch VS2 is closed in the fourth step of the final stage, current flows from the tap winding W to the neutral point or the line end N via the tap selector TS2, the vacuum switches VS2 and VR2, and the tap selection is performed. The operation of transferring the current from the device TS1 to the device TS2 is completed. In the case of the operation of transferring the current from the tap selector TS2 to the TS1, the operation may be performed in the order from the fourth step to the first step, contrary to the above.

As a problem of such a vacuum switch type tap changer at the time of load, there is a decrease in withstand voltage and a decrease in cutoff performance due to a decrease in the degree of vacuum (also called vacuum leakage) of the vacuum switch used therein. . If this phenomenon occurs, a short circuit may occur directly between taps due to a failure to shut off the vacuum switch, which may cause a serious accident that causes fatal damage to the transformer.

This problem will be described with reference to FIGS. In order to explain the above phenomenon, the vacuum switch VS1 is now opened in the first step, but the withstand voltage of the vacuum switch VS1 is reduced due to a decrease in the degree of vacuum inside the vacuum switch, and the arc is continued due to failure to cut off. Assume the case. Then, the current still flows from the tap winding W to the neutral point or the line end N via the tap selector TS1, the vacuum switches VS1 and VR1.

By the way, in such a circuit, the probability is extremely low (the probability that two vacuum switches cannot be cut off at the same time is extremely low), and this phenomenon is hardly possible. Even if the arc of the vacuum switch VS1 is not extinguished in the step but still continues and the arc continues due to the inability to cut off the vacuum switch VR1, the vacuum switch VS1 is finally set in the fourth step.
2 is closed, a circulating current flows from the tap selector TS1 to the tap selector TS2 via the vacuum switches VS1, VR1, VR2, VS2, and a direct short circuit between the taps occurs.
This creates a risk of developing into a major accident.

The same can be said for the reverse switching direction, and any combination of the vacuum switches VS1 and VR1 or VS2 and VR2 causes a decrease in the degree of vacuum.
If the withstand voltage is reduced, a short circuit may occur directly between taps.

To cope with this, conventionally, FIG.
, The vacuum switch VS1 is completely removed from the on-load tap changer (not shown), and its contacts 10a,
10b is opened at a designated interval, and a high voltage is applied to this portion by the impulse voltage generator 21 so that the contacts 10a, 10b
A method of confirming the presence or absence of dielectric breakdown between the electrodes b has been adopted. If the dielectric breakdown occurs, the degree of vacuum is reduced, and if there is no dielectric breakdown, it is determined that the vacuum is maintained.

Incidentally, this type of technology is disclosed in
Japanese Patent Application Publication No. -2061414 and Japanese Patent Publication No. 42574/1994.

[0017]

In the above prior art, no consideration is given to application to a vacuum switch or the like that is mounted on a load tap changer, and the processing required for abnormality detection becomes complicated, There are problems such as difficulty in improving the accuracy of abnormality detection.

That is, in the prior art, when the abnormality detection processing is performed while the vacuum switch is still mounted on the tap changer under load, the test voltage is high. Insulation coordination becomes a problem, and there is an inconvenience that the possibility of dielectric breakdown increases between a vacuum switch mounting part other than the vacuum switch and a nearby metal part.

In particular, such a vacuum switch cannot confirm a decrease in the degree of vacuum during operation. For confirmation, the vacuum switch is used immediately before sending the product to the site or for a limited time during the on-site inspection. The test will be performed. Therefore, the atmosphere must be in the air with a low dielectric strength, and the possibility of dielectric breakdown in parts other than the vacuum switch further increases, and the inspection time on site is limited. In some cases, the vacuum switch cannot be removed, and it may not be possible to confirm whether or not the vacuum degree of the vacuum switch has dropped during the on-site inspection.

The present invention has been made in view of the above points, and it is possible to easily detect a decrease in withstand voltage due to a decrease in the degree of vacuum of a vacuum switch in a mounted state, and to cause an accident in a vacuum switch type tap changer under load. It is an object of the present invention to provide a vacuum switch abnormality detection device capable of preventing the occurrence of the abnormality.

[0021]

The above object is achieved by a power supply means for applying a voltage between terminals of a vacuum switch via a resistor,
Voltage measuring means for monitoring a voltage appearing between the terminals of the vacuum switch, and switching the vacuum switch from a closed state to an open state while applying a voltage to the vacuum switch by the power supply means. The voltage waveform observed by the voltage measuring means is a distortion waveform caused by glow discharge.
This is achieved by detecting an abnormality of the vacuum switch when detected.

[0022]

When a vacuum switch is closed, current flows between the contacts when the vacuum switch is closed by a power supply of several tens of volts connected between the vacuum switches. At this time, if the degree of vacuum of the vacuum switch is sufficiently maintained,
When the contacts open, the recovery voltage between the contacts is sufficiently higher than the glow discharge voltage, so the voltage waveform becomes an undistorted rectangular wave, and on the contrary, it is distorted if the degree of vacuum is reduced or broken It becomes a waveform. Therefore, it is possible to determine the abnormality of the vacuum switch.

Such a determination process can be performed without removing the vacuum switch from the load tap changer, and if a decrease in the vacuum degree of the vacuum switch is recognized, it is determined that a short circuit has occurred, and the vacuum switch is replaced. Thus, the possibility of occurrence of an accident can be easily known before a major accident occurs, and the accident can be prevented from occurring.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. 1 to 6 show one embodiment of the present invention. Note that the same reference numerals are given to the same portions as those in the prior art described in FIG. 7 and FIG.

First, in the embodiment of FIG. 1, reference numeral 1 denotes a number 1 for applying a voltage in parallel between the electrode terminals of the vacuum switch VS1.
0 V DC power supply, 2 voltage measuring means for measuring the voltage waveform appearing between the contacts of the vacuum switch VS1, 3
Reference numerals a and 3b denote clip-shaped terminals for connecting the terminals of the DC power supply 1 to both ends of the vacuum switch VS1, and the shape of these clip-shaped terminals 3a and 3b can be easily changed as shown in FIG. It is made in a structure that can be connected to terminals and conductor parts connected to it. Reference numeral 4 denotes a resistor which functions to enable the voltage measurement means 2 to measure a voltage waveform between contacts. Needless to say, the whole of FIG. 1 forms the main part of the tap changer under load of the transformer.

Next, the vacuum switch VS according to this embodiment
An abnormality detection process for determining whether or not the degree of vacuum is reduced will be described. First, in the detection process, the transformer having the tap changer is disconnected from the electric circuit. Then, this figure 1
As is clear from FIG. 2, one of the wirings is disconnected in advance only for the resistor R1, and the clip-shaped terminals 3a and 3b are connected to the terminals of the vacuum switch VS1. At this time, it is assumed that the open / closed state of each vacuum switch is in the illustrated state. Then, the vacuum switch V
In S1, a current of a predetermined current value flows from the DC power supply 1 via the resistor 4; however, at this time, since the contact of the vacuum switch VS1 is closed, Voltage measurements indicate zero voltage.

Therefore, in this state, the tap changer is operated while monitoring the voltage between the contacts by the voltage measuring means 2, and the vacuum switch VS1 and the vacuum switch VS2 are mechanically operated from the closed state of the vacuum switch VS1. Is operated to switch from the tap TS1 to the tap TS2. Then, when the vacuum switch VS1 is opened, the current from the DC power supply 1 is cut off.

In this case, if the degree of vacuum of the vacuum switch VS1 is sufficiently maintained, the recovery voltage between the contacts when the contacts are opened is sufficiently higher than the glow discharge voltage. The resulting voltage waveform is a short wave without distortion as shown in FIG.

However, if the vacuum of the vacuum switch VS1 is broken and air is leaking into the inside, glow discharge between the contacts occurs at the start of the opening of the contacts due to the air existing inside the switch. The observation result of the voltage waveform by the voltage measuring means 2 is a distorted waveform as shown in FIG.

Therefore, according to this embodiment, it is possible to reliably check whether or not the vacuum of the vacuum switch VS1 has been broken only by judging the observation result of the voltage waveform by the voltage measuring means 2. At the time of production or on-site inspection,
Without removing the vacuum switch completely to a single item,
Abnormality of the vacuum switch can be easily detected while being attached to the load tap changer.

Next, in order to check the other vacuum switches VR1, VR2 and VS2, a circuit consisting of a DC power supply 1 of several tens of volts, a voltage measuring means 2, and a resistor 4 is provided at both ends of the vacuum switch to be tested. Clip-shaped terminal 3a,
By connecting at 3b, it can be implemented similarly. At this time, in order to check the vacuum switches VS1 and VS2, it is necessary to disconnect one of the resistors R1 and R2 only at the time of the test, as described in the case of the vacuum switch VS1. Vacuum switch VR
1, In the case of VR2, without disconnecting any connection at all,
Testing is possible with the device mounted.

The above concept of the present invention is basically based on the fact that a current is first applied between the contacts of a vacuum switch, and then the recovery voltage between the contacts when the contacts are opened is observed. Therefore, the present invention can be applied to not only the circuit shown in FIG. 1 but also any type of vacuum switch type on-load tap changer.

FIG. 5 shows another embodiment of the present invention. The same reference numerals as those in the embodiment of FIG. 1 denote the same parts. In the embodiment of FIG. 5, the present invention is applied to a vacuum-switch-type on-load tap changer in which the vacuum switch VR2 and the resistor R2 in the embodiment of FIG. 1 are omitted, and the circuit is simplified.
In this case, since there is no vacuum switch connected in series in FIG. 1 and only one of the vacuum switches VS1 or VS2 causes a short circuit between the taps when the degree of vacuum is reduced, the effect of the application of the present invention is more significant. It is even better. The operation required for the abnormality detection is the same as that in the embodiment of FIG.

FIG. 6 shows still another embodiment of the present invention. The same reference numerals as those in the embodiment of FIG. 1 denote the same parts. In FIG. 6, reference numeral 11 denotes an input circuit for inputting a voltage detection value between the vacuum switches VS1, and 12 denotes a comparison determination circuit. Reference numeral 10 denotes a vacuum switch abnormality determination device including the portable DC power supply 1, the insertion resistor 4, the input circuit 11, and the comparison determination circuit 12.

Next, the operation of this embodiment will be described. When the illustrated vacuum switch VS1 is closed, the vacuum switch VS1 is mechanically opened, and a tap switching operation to the vacuum switch VS2 is performed. Then, the vacuum switch V
When S1 opens, a recovery voltage having a waveform shown in either FIG. 3 or FIG. 4 is generated between its contacts. On the other hand, the comparison determination circuit 12 has a recovery voltage waveform in a normal state where the vacuum degree of the vacuum switch does not decrease in advance (a waveform in FIG. 3) and a recovery voltage waveform in an abnormal case where the degree of vacuum decreases. (The waveform of FIG. 4) and store them, and the input circuit 11
And makes a comparison judgment with the voltage detection value input to the comparison judgment circuit 12. Then, when the recovery voltage waveform pattern matches the waveform of FIG. 4, it is determined that there is an abnormality such as a decrease in the degree of vacuum. Note that when the recovery voltage waveform pattern deviates from the waveform of FIG. 3 by a certain degree or more, it may be determined that there is an abnormality.

Therefore, according to this embodiment, since the judgment result is clearly divided into "normal" and "abnormal" from the comparison / judgment circuit 12, abnormality detection is easy.
Even better effects can be expected.

In each of the above embodiments, the DC power supply 1 is used. Therefore, for this power supply,
A portable DC power source such as a battery is required. Alternatively, a DC voltage may be obtained from an AC power source by a rectifier circuit or the like. According to such an embodiment, a commercial power source is used. Therefore, there is an effect that it becomes simple.

According to the detection principle of the present invention, an AC power supply can be used as it is instead of a DC power supply, and according to such an embodiment, the apparatus can be further simplified.

[0039]

According to the present invention, an abnormality such as a withstand voltage drop due to a vacuum break of a vacuum switch can be easily and reliably detected in a state of being mounted on a tap changer under load. Therefore, it is possible to prevent accidents by applying to vacuum switch type tap changers under load, detecting the possibility of short circuit between taps in advance, and taking appropriate measures to prevent accidents. Can be prevented beforehand, and the reliability can be sufficiently improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a case where an embodiment of a vacuum switch abnormality detecting apparatus according to the present invention is applied to a tap changer under load.

FIG. 2 is an explanatory view of a clip-shaped terminal according to one embodiment of the present invention.

FIG. 3 is a waveform diagram in a normal state according to the present invention.

FIG. 4 is a waveform chart showing an abnormal state in the present invention.

FIG. 5 is a block diagram showing another embodiment of the present invention.

FIG. 6 is a block diagram showing still another embodiment of the present invention.

FIG. 7 is a block diagram showing an example of a vacuum switch-type on-load tap changer.

FIG. 8 is an explanatory diagram of a switching sequence in an example of a vacuum switch type on-load tap changer.

FIG. 9 is an explanatory view showing a conventional example of a vacuum switch abnormality detection method.

[Explanation of symbols]

 W tap winding TS1, TS2 Tap selector VS1, VS2, VR1, VR2 Vacuum switch R1, R2 Resistor N Neutral point or line end 1 DC power supply 2 Voltage measuring means 3a, 3b Clip-shaped terminal 4 Resistance 10 Abnormality judgment circuit 11 input circuit 12 comparison judgment circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01F 29/04 502 G01M 3/40 H01H 33/66

Claims (5)

(57) [Claims] 1. A power supply means for applying a voltage between terminals of a vacuum switch via a resistor, and voltage measuring means for monitoring a voltage appearing between the terminals of the vacuum switch, wherein the power supply means applies a voltage to the vacuum switch. The vacuum switch is switched from the closed state to the open state while the voltage is being applied, and at this time, the voltage waveform observed by the voltage measuring means is glowed.
A vacuum switch abnormality detecting device configured to detect abnormality of the vacuum switch when the waveform is detected as a distortion waveform due to discharge ; 2. The vacuum switch abnormality detecting device according to claim 1, wherein a connection portion to said vacuum switch is constituted by a clip-shaped terminal. 3. The invention according to claim 1, wherein said voltage measuring means compares an input circuit for inputting a voltage between contacts of a vacuum switch with a predetermined pattern from a waveform pattern of the voltage between contacts input from the input circuit. An abnormality detection device for a vacuum switch, comprising: a comparison determination circuit for performing an abnormality determination by performing an abnormality determination. 4. The vacuum switch abnormality detecting device according to claim 1, wherein the voltage applied to the vacuum switch by the power supply means is an AC voltage. 5. The vacuum switch abnormality detecting device according to claim 1, wherein the vacuum switch is a vacuum switch mounted on a vacuum switch type load tap changer.