JPS6030186B2 - voltage suppressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects dielectric breakdown or partial discharge of a discharge charge amount exceeding a set value in a specimen (for example, a capacitor, a resistor, a cable, etc.) connected to a high-voltage side terminal on the secondary side of a transformer. Insulation that suppresses competitive current or eliminates partial discharge by holding the specimen at a low potential to reduce the standard deviation of the dielectric breakdown voltage value or partial discharge voltage value of the specimen. Regarding destructive testing equipment.

If insulation breakdown occurs in power equipment,
A discharge current flows through the power system, but in order to protect equipment, etc., it is common to operate a disconnector to disconnect the power from the power system.

However, during the time (hereinafter referred to as "operation time") from when the specimen undergoes dielectric breakdown until the mustard circuit breaker operates, a follow-on current flows into the specimen from the power supply side. This competitive current causes more damage to the electrode surface and more damage to the deterioration traces of the insulator under test. Additionally, when the breaker operates, overvoltage may be induced on the secondary side through the transformer due to electromagnetic induction, and this overvoltage may further damage the electrode surface and cause damage to the deterioration of the insulator under test. This caused the problem of affecting the next dielectric breakdown voltage value and partial discharge voltage value. In addition, such a long-time follow-on current causes irregularities in the electrode surface and produces discharge deterioration products, which is extremely inconvenient for investigating discharge characteristics under certain conditions.

As an improved method of the above-mentioned primary side insulation failure method, when dielectric breakdown occurs in the specimen on the secondary side of the transformer, the discharge current is used to connect the specimen in parallel to the primary side of the transformer. There is a method of operating the semiconductor device and then turning off the power.

There is also a method that improves this method and operates a semiconductor element connected in series to the primary side of a test transformer to quickly cut off the power supply. Since these methods involve cutting off the primary side of the test transformer, overvoltage may be induced on the secondary side of the test transformer in the same way as described above. Therefore, there is a need for a method to directly suppress the competitive flow after the breaker operates.

As a method for suppressing such follow-on current, a method is known in which an air gap connected in parallel with the specimen is controlled using, for example, a thyratron. However, even in this method, since an air gap is used, discharge degradation products are formed due to the spark voltage of the gap, and the specimen cannot be controlled under constant conditions. Therefore, it has been considered to further replace the thyratron and the like with semiconductor elements.

As such a semiconductor element, a controlled rectifying element (hereinafter referred to as SCR) such as a thyristor is suitable, but at present the withstand voltage of SCR is about 1800 volts, so
In order to prevent a voltage higher than this withstand voltage from being applied to one SCR, it is necessary to use a plurality of SCRs connected in series.
When using multiple SCRs connected in series in this way,
A particular problem concerns the ignition means for turning on all of the SCRs at once.

In other words, for multiple SCRs connected in series, if each SCR is not fired at the same time, a voltage higher than the withstand voltage will be applied to the SCR that is not fired, resulting in the inconvenience of destroying this SCR. This is because there were some problems. Therefore, in this type of device in which a plurality of SCRs are connected in series, various ignition means have been developed and provided.Firstly, there is a means for igniting a large number of SCRs connected in series or in parallel at once. The point is that the same number of pulse transformers as the SCR are provided, each secondary winding is arranged between the gate and cathode of the SCR, and the primary winding is commonly connected to a pulse current generator. Arc means are provided.

Ignition means with this configuration, especially when connected in series, are often used at high voltages, making it difficult to insulate the pulse transformer, resulting in high insulation costs and additional costs. However, there was a problem in that it was not possible to obtain an efficient pulse transformer.

Secondly, a follow-up ignition method may be considered in which the ignition of one SCR is performed and the next SCR is ignited in sequence, such that when one SCR is ignited and turned on, the next SCR is ignited. According to this method, when the number of SCRs connected in series is small, there is no problem because the firing delay time is small, but if the number of SCRs increases, the firing will be delayed sequentially from the firing of the first SCR, so the firing of the first SCR will be delayed. The ignition of the SCR is now considerably delayed from the first one. Therefore, there is a problem in that a voltage higher than the withstand voltage is instantaneously applied to the SCR, resulting in decreased reliability or destruction. For this reason, thirdly, a plurality of SCRs are connected in series, and the control electrode (hereinafter referred to as "gate J") of each SCR is connected in series.

) A resistor and a photoelectric element that converts an optical signal into an electrical signal are arranged in series between the cathode (hereinafter referred to as "cathode"), and an ignition is carried out between the cathode and the connection point of the low resistance photoelectric element. It is also possible to control the ignition by providing a power source for the ignition and inputting the ignition optical signal to this photoelectric element using a sacrificial light pipe, but it is said that a movable light pipe is extremely expensive. This is inconvenient and requires a light source with sufficiently high brightness because the optical signal is attenuated when the flexible light pipe is lengthened. Furthermore, fourthly, as an ignition means for simultaneous ignition, multiple SCRs are connected in series and radio waves are used, the ignition signal generator is used as a wireless transmitter, and the ignition circuit includes a wireless receiver. A method of configuring it as a circuit and firing all at once is considered, but if the modulation method is amplitude modulation, it will be susceptible to noise and there will be dust that may cause malfunctions, and if it is frequency modulation, the whole device will be complicated. This has the disadvantage that the cost is high.

Further, both the overlapping and offset ignition means are for direct current high voltage and cannot be used with alternating current high voltage, which is an extremely inconvenient problem.

The present invention has been made in view of the above-mentioned points, and is caused by the traverse current or partial discharge that flows through the specimen during the time from when the specimen undergoes dielectric breakdown until the primary side circuit breaker operates. It is possible to completely suppress current, reduce damage to the electrode surface of the specimen, and minimize changes in dielectric breakdown voltage or partial discharge voltage over time, making economical design easier in the insulation design of power equipment. It is an object of the present invention to provide a voltage suppression device for reducing the formation of discharge degradation products. In order to achieve the above object, the present invention has a means for detecting the discharge current generated in the specimen and operating a disconnector provided on the primary side of the transformer, and a means provided in parallel with the aforementioned specimen. , a first circuit formed by connecting a resistor in series to a circuit in which a plurality of controlled rectifying elements are connected in series in the forward direction, and this first circuit is connected in parallel in the opposite direction and has the same circuit configuration as the first circuit. a resistor provided in parallel with each control rectifier of the first and second circuits, and a voltage source that applies an ignition voltage to each control electrode of each control rectifier; , a photoelectric element for controlling the coupling between the voltage source and the control electrode, an ignition signal forming circuit for detecting and amplifying the discharge current from the specimen to generate an ignition signal; This dielectric breakdown test device includes a light emitting element that controls the photoelectric element according to an ignition signal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to illustrated embodiments.

In FIG. 1, reference numeral 1 is a light current exposure source device, 2 is a wire cutter, 3 is a voltage regulator, 4 is a current detector, and 5 is a test transformer. detects excessive current on the primary side of
The application can be stopped. The transformer 5 is
A power supply voltage Vo is derived from the secondary side, and a current limiting resistor RD is connected to one voltage line (also referred to as a voltage terminal). The following circuit is interposed between this voltage line and the other voltage line L. That is,
S.R. , S.R. 2,...,SR,n are SCRs connected in series with their polarities in the negative direction, and each SC
R(SR,.,SR.2,...,SR,n) has each S
A resistor R, . which averages the shared voltage of CR, . ,R,2,...
, R, n are connected in parallel.

This SCR (SR,.,SR,2,...,SR,n)
The first circuit is configured by further connecting a resistor R^ in series to a series-parallel circuit of resistors (R,.,R,2,...,R,n). The characteristics are connected from the voltage terminal to the terminal L. And each SC
Each gate of R (SR, ., SR, 2,..., SR, n) is connected to an ignition power source, . , E, 2, . . . , E, n are connected, and each cathode is connected to a resistor Ra.
, , Ra2 . . . , Ran are connected at one end.

One end of each of the resistors Ra, Ra2, . . . , Ran is connected to each other. This resistance Ra,, Ra2,..., R
At each other end of an, a photoelectric element LS, . , is, 2,..., LS, n
Power supply E, . , E,2, . , is, 2,...,LS
, n becomes conductive, so that an ignition voltage is applied to the gate. Then the second circuit
The circuit configuration is the same as that of the circuit shown in FIG.
This is something that has been established for several days.

That is, SCR(SR2,,SR22,...,SR
2n) are connected in series in the forward direction, and these SC rules are as follows:
A resistor R2.R equalizes the shared voltage of R. ,R22,...
, R2n are connected in parallel.

These resistors R2,, R22,..., R2n) and SCR(
SR2, SR22, . In addition, each SCR (SR2,,SR22,...,SR
2n) and between each gate and each cathode, an ignition power source E2,, E22,..., E2n, and a photoelectric element LS2, which is for ignition control and connects and controls the ignition power source. ．． L
S22,..., LS2n and resistors Rq, RQ..., Rbn
A series circuit is constructed for each subscript of each code consisting of, that is, a series circuit with E2, - hare - Rb as a set, E2
2-LS prisoner-Rb2 as a set, and these series circuits are arranged between the gate and cathode of each SCR corresponding to the regular letter of the code of each SCR.

Next, these SCRs (SR,.,SR,2,...S
As a light source for igniting each of the forward connected photoelectric elements LD, .
,LD,2,...,LD,n and photoelectric element LD milk, LD2
2,... Consisting of a combination with LD2n, the photoelectric element L
D. At the intersection of and LD2, there is a reset switch RS.
The output terminal h of the ignition signal generation circuit PG which performs an amplification function is connected through T, and the reference potential terminal 1 of the ignition signal generation circuit PO is connected to the intersection of the light emitting elements LD,n and LD2n. There is.

Here, the reset switch RST is a switch for resetting each SCR, and is temporarily opened after all SCRs are fired at once.

Further, an ignition control device CTL is connected to the input terminal of the ignition signal generation circuit PG, which detects a discharge current, etc., and controls and outputs an output signal of the ignition signal generation circuit PG.

Therefore, this ignition signal generating circuit PG is configured to control each of the light emitting elements LD, . ,LD,2,...,
The signal polarity is such that LD,n emits light, and conversely, when the voltage terminal side is negative, each light emitting element LD2,,LD2
2, . . . , the signal polarity is such that the LD2n emits light. The ignition control device CTL inputs and amplifies the discharge current and outputs the ignition signal generation circuit PG at the next stage.
The configuration is such that it can supply its output to the circuit PG and control the input signal of the circuit PG.

Further, the ignition signal generation circuit PG is connected to the ignition control device CT.
The ignition current of the light emitting element LD is controlled by controlling the amplified ignition signal from L again. An input terminal for detecting discharge, etc. is provided at the end of the control device CTL for ignition control, and one end is connected to the voltage terminal L through a coupling capacitor CK, and the other end is connected to the voltage terminal L. There is.

Further, a test object Cx such as a capacitor or a cable is connected between the voltage terminals H and L. Furthermore, in this embodiment, photoelectric elements LSn, LS, 2, . . .
, LSm and light emitting element LD, . ,LD,2,...;LD
For each pair with m, and the photoelectric element is 2,, is 22,...
・Melon 2n and light emitting element LD2, LD shoes..., LD2n
The device is constructed by being housed in a pressurized container filled with an insulating gas, or the entire device is housed in an insulating pressurized gas. As a result, insulation can be improved and the distance to the light emitting element can be shortened, making it possible to obtain a compact and efficient ignition means. In addition, the ignition power source (E,.,E,2,...,E,n,E2,,E22,...
, E2n) are constructed of solar cells or the like, and are obtained by constantly inputting light from a light source (not shown).

The operation of the embodiment of the present invention having the above configuration will be explained.

If the specimen Cx starts to discharge (partially) due to some reason, a discharge current will flow from the coupling capacitor CK to the specimen Cx.

This current is led to the next-stage ignition signal generation circuit PG as an ignition control signal via the ignition control device CTL. The ignition control signal detected by this ignition control device CTL is
Since the current is very small, it is amplified by the ignition control device CTL.

Then, a controlled ignition signal is output from the ignition signal generation circuit PG, and the light emitting elements LD, . ,LD,2,...,L
D, n series circuit and light emitting elements LD2,, LD22, .
..., each ignition signal is applied to the series circuit of LD2n. This ignition signal is a pulse-like signal having positive and negative polarities, and its period is synchronized with the frequency of the power supply No., and the light emitting elements LD, . ,L
D,2,...,LD,n emits light, and at the moment when the voltage terminal becomes negative polarity, LD illusion, LD22,...,LD2
n is applied so as to emit light. As described above, each light emitting element LDI·, LD12, . ．． ．． ,LD・n,1''D2
1,LD already',. -LD2n emits light. And photoelectric elements LS, . ,LS,2,...,LS,n,mountain 2,
, is 22,...,LS2n conducts at each instant, and each SCR
(SRI・,SR12,.,.,SR]n,SR21,
The ignition power supply E, . ,E,2,...,E,n,E2,,E2
Current is supplied from 2, . . . , E2n, respectively.

In this case, each SCR (SR,.,SR,2,...,SR,
n, SR2,, SR22,...SR2n) gate'
In order to hasten the turn-on time, a current to the extent that the cathode does not turn on is applied to the resistors Ra,, Ran, Rb, ~
It is set by Rbn. As mentioned above, the gate of that SCR.

When a current is supplied between the cathodes, SCR (SR, .,
SR,2,...,SR,n,SR2,,SR22,...,S
R2n) is instantaneous (on the order of microseconds). ), they will turn off all at once in each cycle. As a result, the voltage terminal H - now the resistance value of the first rectifier circuit [each SCR (S
R,. , SR, 2, ..., SR, n)] or the resistance value of the second rectifier circuit [each SCR (SR2,, SR22, ..., SR2n) )
The resistance value is the sum of the forward direction resistance of the resistor RB and the resistor RB.

Therefore, the voltage between the voltage terminals H and L decreases due to the conduction of the resistor Ro and each SCR of this voltage control device, and the voltage across the specimen Cx becomes below the discharge starting voltage value, so the discharge must be stopped. I can do it.

Furthermore, the resistance R.

The voltage Vx between the voltage terminals HL of the high voltage suppression circuit can be set to a desired value by allocating the resistance values of the resistors R^ and RB. On the other hand, when each SCR becomes short-circuited, the current on the primary side of the transformer 5 changes, so the detector 4 detects this change and drives the sheath breaker 2.

Therefore, the shield breaker 2 disconnects the AC power supply 1 and the secondary side of the transformer 5, and the current Vo is no longer applied to the specimen Cx. Therefore, the safety when removing the specimen Cx that has caused dielectric breakdown from the apparatus is improved, and the induced overvoltage generated on the secondary side of the transformer 5 when the insulation breaker 2 is operated can be suppressed. Furthermore, when the circuit breaker 2 is restored, by temporarily opening the reset switch RST, each of the SCRs that have been made conductive can be turned off, thereby preparing for the next discharge. In FIG. 2, the horizontal axis represents time t, and the vertical axis represents voltage V.

In FIG. 2A, the waveform marked 1 represents an example of the voltage waveform of the power supply Vo, and the waveform marked 0 indicates that the secondary side circuit of the present invention operates and the voltage between the voltage terminals H and L is suppressed. It shows.

In Figure 2, the waveform example 1 indicates the voltage across the resistor RA, and the waveform example 0 indicates the voltage across the resistor RB.

When the first circuit is operating, the voltage appears on the resistor RA, and a sine wave part appears as shown in (1), and when the second circuit is operating, the voltage appears as shown in (1). The sine wave part appears.

In addition, the t-operation display device can be easily installed by using the ignition control device CTL, and the resistors RA and R
By adding an operation display device to B, the operation status can be easily confirmed.

In this way, when a discharge occurs in the specimen Cx, the discharge pulse current can be instantly suppressed or extinguished, and the generation of discharge deterioration products on the electrode surface of the specimen Cx can be extremely reduced. , it is possible to prevent pressure changes in the voids of the donor body Cx.

For this reason, the test specimen Cx can be used to measure small variations in dielectric breakdown voltage or partial discharge inception voltage, with less discharge deterioration. ``If power equipment is designed using this voltage value as a guideline, it will lead to savings in insulating materials.'' This results in resource saving and reliable insulation design.In addition, in the specimen whose discharge current is suppressed by the present invention, discharge deterioration products are formed in spots corresponding to the number of discharges, and , concentrated in one small area.

Therefore, it is possible to know the influence of discharge deterioration products generated by multiple discharges on the dielectric breakdown voltage value or partial discharge inception voltage. As a result of this,
It was found that the discharge currents were similar despite differences in the electrode surface conditions. As described above, according to the present invention, the high voltage applied to the specimen is short-circuited at high speed based on the discharge current at the start of discharge of the specimen, so that the current is reduced at the moment when the discharge occurs. This has the effect of reducing damage to the surface of the specimen and suppressing changes in the dielectric breakdown voltage value over time, thereby realizing the insulation design of power equipment reliably at low cost.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing an embodiment of the present invention, Figure 2 A is a diagram showing the relationship between the power supply and voltage terminals, and Figure 2 shows the resistor R.
It is a diagram showing voltage waveforms across A and RB. 1...AC power supply device, 2...〇Shiya disconnector, 3
...Voltage regulator, 4...Current detector,
5... Test transformer, SR, . ,SR,2,・
..., SR, n, SR2,, SR2,..., SR2n...
...Control rectifier, Melon,,,LSI2,...B,n,
LS2. , B22,..., B2n... photoelectric element,
LD,. ,LD,2,...,LD,n,LD2. ,L
D2,...LD2n...Light emitting element, E,... ,E,2,
..., E, n, E2,, E22,..., E2n...
...Ignition power supply, Cx...Coupling capacitor. Zu Shigeru Figure 2

Claims (1)

[Claims] 1. If dielectric breakdown or a partial discharge with a discharge current exceeding a set value occurs in a specimen connected to the high-voltage terminal on the secondary side of a transformer, the high-voltage part of the specimen is A device that maintains a low potential and suppresses follow-on current or extinguishes partial discharge, and detects changes in current on the secondary side of the transformer and activates a circuit breaker installed on the primary side of the transformer. means for operating,
A first circuit that is provided in parallel with the specimen and is formed by connecting a resistor in series to a circuit in which a plurality of controlled rectifying elements are connected in series in the forward direction.
a second circuit connected in parallel in the opposite direction to the first circuit and having the same circuit configuration as the first circuit;
a resistor provided in parallel with each controlled rectifying element of the first and second circuits; a voltage source that applies an ignition voltage to each control electrode of each controlled rectifying element; this voltage source and the control electrode; a ignition signal forming circuit that detects and amplifies a discharge current from the specimen to produce an ignition signal; and an ignition signal forming circuit that is optically coupled to the photoelectric element and generates the ignition signal according to the ignition signal. A dielectric breakdown test device comprising a light emitting element for controlling the element. 2. The voltage suppression device according to claim 1, wherein at least the photoelectric element and the light emitting element are housed in an insulating pressurized gas.