JPH033328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum degree monitoring device for a vacuum shield breaker.

Generally, the vacuum degree of a vacuum disconnector is 10 ^-4 Torr.
It is normal or has the ability to break at pressures below,
This vacuum level may deteriorate due to gas released from inside the breaker or disconnector, or slow leakage from joints such as welding and brazing, resulting in a decrease in breaker ability. For this reason, when using a vacuum chamber or disconnector, it is essential to monitor the degree of vacuum in order to guarantee performance.

Conventionally, therefore, a discharge electrode is provided inside the vacuum chamber or disconnector, and a high voltage is applied from a separate power supply, and the degree of vacuum is checked by taking advantage of the fact that the state of discharge at this time changes depending on the degree of vacuum. However, with this method, the structure of the vacuum shield and disconnector was complicated, and a separate high-voltage power source had to be provided, making it expensive. Also, when checking the degree of vacuum, if the vacuum shield or breaker is disconnected from the circuit, open the movable electrode of the vacuum shield or breaker from the fixed electrode by a distance that is likely to cause discharge due to vacuum deterioration, and connect the A voltage was applied, and the quality of the vacuum was judged based on the discharge state at this time. This method required turning off the power, which was very troublesome.

In addition, in recent years, compact substation equipment has been developed, and vacuum shields and disconnectors are also used in this equipment. To check the degree of vacuum in the vacuum shield or disconnector in this equipment, the insulating medium (oil or gas) inside the equipment must be extracted, and the vacuum shield or disconnector must be disconnected from the circuit as described above. It was on. For this reason, this checking means has the drawback of being very time consuming. Furthermore, with the above method, there was a possibility that accidents could occur due to human assembly errors.

The present invention eliminates the above-mentioned drawbacks, does not require a discharge electrode or a separate high-voltage power source, and allows the vacuum circuit breaker housed in a case kept at ground potential to remain connected to the circuit. It is an object of the present invention to provide a vacuum degree monitoring device for a vacuum chamber or disconnector which can check the degree of vacuum, and which can check the degree of vacuum simply and inexpensively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, a vacuum shield and disconnector will be described. In Fig. 1, 1 is a vacuum shield disconnector.The vacuum shield disconnector 1 has metal end plates 3 and 4 attached to both ends of an insulating cylinder 2 to form a vacuum container, and is fixed to the end plate 3. While the lead 5 is inserted, a movable lead 7 is movably inserted into the end plate 4 via a bellows 6, and a fixed electrode 8 and a movable electrode 9 are attached to the tips of the fixed lead 5 and the movable lead 7, respectively. Further, a shield 10 is installed in the middle of the insulating cylinder 2 to prevent metal vapor generated between the chopping electrodes 8 and 9 from adhering to the inner surface of the insulating cylinder 2. 11 and 12 are auxiliary shields, 13 and 14 are external connection conductors, and 15 is a current collector.

In the above configuration, the vacuum sheath breaker 1 moves the movable lead 7 by an operating device (not shown) and connects and separates the electrodes 8 and 9 for input and disconnection. The equivalent circuit diagram is shown in Fig. 2. In FIG. 2, 28 and 29 are the power supply and load of the circuit in which the vacuum shield breaker 1 is installed, respectively;
30 and 31 are the portion of the fixed lead 5 inside the vacuum container and the resistance and capacitance between the fixed electrode 8 and the shield 10, respectively; 32 and 33 are the portion of the movable lead 7 inside the vacuum container and the movable electrode 9 and the shield 10, respectively.
34a and 34b are the resistances of the insulating tube 2, 35 is the capacitance between the shield 10 and the casing kept at ground potential, and 36 and 37 are the electrodes 8 in the slightly disconnected state, respectively. , 9 are the resistance and capacitance between them. When the degree of vacuum inside the vacuum shield breaker 1 deteriorates, that is, when the internal pressure increases, the capacitances 31, 33, and 37 hardly change because the dielectric constant in vacuum and the dielectric constant in the atmosphere are almost equal. However, the resistances 30, 32, and 36 are significantly reduced due to Patsien's law. Therefore, discharge occurs between the shield 10, which is insulated from both the fixed side and the movable side by the insulating tube 2 and has a floating potential, and each electrode 8, 9, regardless of whether it is in the closed state or the shrunk state. Discharge occurs between the electrodes 8 and 9 only in the disconnected state. This discharge changes depending on the cable (capacitance) connection on the load side, the inductive load line, or the capacitance of the vacuum shield or disconnector lead. Furthermore, even if the power source is on the movable lead side, it works in the same way, but the equivalent circuit in this case is 2 in Figure 2.
The other parts are exactly the same as in FIG. 2 except that 9 is a power source and 28 is a load.

FIG. 3 shows the voltage between the electrodes when the vacuum degree of the vacuum shield breaker 1 is normal. That is, when the degree of vacuum is normal, the voltage waveform between the electrodes 8 and 9 is a sine wave of the commercial frequency as shown in Figure 3, and this sine wave includes a vacuum shield, a rotating machine other than the disconnector, a transformer, etc. The waveform is somewhat distorted because it contains harmonics below 2KHz generated by instruments and meters. FIG. 4 shows the inter-electrode voltage signal when the degree of vacuum in the vacuum shield breaker 1 deteriorates, and the inter-electrode voltage between the electrodes 8 and 9 is as follows:
Although it depends on the distance between the electrodes and the applied voltage, for example, the fourth
As shown in the figure, the voltage does not rise above a certain level, and ripples occur at the leading edge of the waveform. It was obtained from measurements described later that when this ripple occurs, an electromagnetic wave signal (here, electromagnetic waves are radio waves generated due to discharge when the degree of vacuum deteriorates) is generated, which is a commercial frequency with a high frequency of 2 to 20 KHz superimposed. . Deterioration in the degree of vacuum in the vacuum chamber and disconnector 1 can be detected by displaying the occurrence of this signal on an oscilloscope via a bandpass filter as described later. In this case, even if corona discharge occurs in other parts other than between the poles and the vacuum shield, the
Since the signal waveform is different from the Hz electromagnetic wave signal, false detection will not occur.

Here, the electromagnetic waves measured while changing the degree of vacuum between 5×10 ^-3 and 300 Torr were as follows. In other words, when the ground capacitance on the load side is 0.0042μF, it is 10 to 14K.
Hz, 0.05μF includes frequencies of 2 to 8KHz, 0.2μF or 0.2μF or more includes frequencies of 2 to 20KHz, 0.0042μF
The waveform of the electromagnetic waves at this time was pulse-like. Therefore, if the capacitance on the load side is small, connecting a capacitance of about 0.2 μF to the case or ground will result in a frequency of 2 to 20 KHz.
Electromagnetic waves containing the frequency are obtained.

It has also been measured that the signal strength of the electromagnetic waves is greater on the power supply side than on the load side.

Next, an embodiment of the present invention will be described in which the vacuum shield breaker 1 is used in a compact substation equipment. FIG. 5 is a schematic configuration diagram showing the above-mentioned substation equipment in a single wire connection (usually used in three phases). In FIG. 1st
It is connected to the tank 51 via a connection duct 101, and includes a power supply side cable 53a and a load side cable 5.
A second tank 54 houses connection conductors 53c and 53d to the second tank 52, and a duct 1 connected to the second tank 52.
This is a third tank that is connected via 01 and houses a disconnector 55. Each tank 51, 52, 54 and duct 101 are made of metal and are kept at ground potential. The reason for keeping the tank etc. at ground potential in this way will be explained. If vacuum deterioration is detected only when the vacuum switch 1 is open, there is no need to maintain the tank and the like at ground potential.

However, normally, the vacuum shield breaker 1 is closed and in a conductive state. In order to detect vacuum deterioration in this conductive state, when the electrodes 8 and 9 shown in FIG. Does not occur. For this reason, the shield electrode 10 and the lead 5 at a floating potential,
7. Between the electrodes 8 and 9 is an insulator (in this case, the dielectric constant of vacuum is ε' = 1, air or SF ₆ gas has a dielectric constant of ε' =
1) The capacitance C is determined by the dielectric constant and thickness (distance).
is determined and a partial pressure occurs. This partial pressure is likely to occur, and in the event that the degree of vacuum deteriorates, in order to facilitate discharge between the leads 5, 7 and electrodes 8, 9 and the shield electrode 10, which are forced to have the same potential,
It keeps the tank etc. at ground potential. Note that an insulating medium is stored in each tank 51, 52, 54 and duct 101, and each tank and duct are airtightly partitioned by insulating spacers 102, respectively.

The second tank 52 is provided with a voltage detection terminal 57 using a capacitor combination 56 whose details are shown in FIG. In FIG. 6, this terminal 57 connects one end of the capacitor combination 56 to the connecting conductor 53c.
and connect the other end to the outer wall 52 of the second tank 52.
It is provided so as to be led out to the outside via an insulator 58 fixed to a. 59 is a probe for detecting the electromagnetic waves, and this probe 59 is brought into contact with the voltage detection terminal 57. Note that if the probe 59 is directly connected to the voltage detection terminal 57, if the capacitor coupling constant is large, a large commercial frequency output will be detected, which may destroy equipment connected to the subsequent stage. For this reason, the probe 59 has a built-in attenuator that reduces its output to a predetermined level. 60 is a band pass filter that passes electromagnetic wave signals of 2 KHz to 20 KHz, and the output of this filter 60 is input to an oscilloscope 61.
The reason why the voltage detecting terminal 57 is disposed inside the second tank 52 is that the second tank 52 is made of metal, so that the electromagnetic wave shielding effect is very good. Therefore, the weak discharge electromagnetic waves accompanying the discharge are suppressed and do not come out to the outside. Therefore, in order to facilitate the detection of vacuum deterioration, it is necessary to install a terminal outside the tank to extract this electromagnetic wave.

Now, when the vacuum level of the vacuum shield breaker 1 is normal, the voltage waveform between the electrodes 8 and 9 is a sine wave of the commercial frequency as shown in FIG. When the sine wave is detected and its output is passed through a band pass filter 60, since the sine wave has a frequency of 50 Hz or 60 Hz, it is removed by the filter 60 and sent to the oscilloscope 6.
1 is not displayed. FIG. 7 shows a waveform when the output of the probe 59 is input directly to the oscilloscope 61 without providing the bandpass filter 60, and this waveform is the same as that in FIG. 3.

Here, if the degree of vacuum in the vacuum chamber breaker 1 deteriorates, glow discharge begins between the electrodes 8 and 9. The waveform at this time is shown in FIG. When the discharge starts, an electromagnetic wave signal in which a frequency of 2 KHz to 20 KHz is superimposed on a commercial frequency is generated as described above, and this signal appears at the voltage detection terminal 57. When this signal is input directly to the oscilloscope 61 via the probe 59, a distorted sine wave component is displayed as shown in FIG. 8A. In addition, the probe 59
When the output is input to the oscilloscope 61 through the bandpass filter 60 and displayed, a waveform as shown in FIG. 8B appears. In this way, the oscilloscope 6
Deterioration of the degree of vacuum can be detected by observing the waveform appearing in 1.

Figure 9 is called the Patsien curve.
According to this curve, no discharge occurs in the good vacuum region A. In the vacuum deterioration region B, the discharge voltage is determined by the product of the pressure P and the distance between the electrodes or the gap d between the metals. In this region B, the larger d is, the easier the discharge is, which is completely opposite to the normal atmospheric discharge state, where the smaller d is, the easier the discharge is. In this region B, discharge starts when the degree of vacuum falls below the degree of vacuum commensurate with the discharge voltage. This discharge is an intermittent discharge similar to a glow discharge, and is established with very little energy.
Along with this discharge, electromagnetic waves were emitted as noise. When this noise is measured with a spectrum analyzer, it is found that it contains many frequencies from several tens of Hz to several MHz, and from this frequency band, a frequency that does not malfunction due to other external noise is selected, and it becomes the above-mentioned 2 to 20 KHz. .

In the above embodiment, the case where the electrodes of the vacuum shield breaker 1 are open has been described, but even when the electrodes are closed, the equivalent circuit is as shown in FIG. Since the capacitance 37 and the resistor 36 are short-circuited, and discharge occurs between the electrodes and leads and the intermediate shield having a floating potential, the deterioration of the vacuum degree can be detected in the same manner as described above.

When the electrode is closed as described above, the potential of the shield, which is a floating electrode, is determined by capacitance as described above. When the electrodes are closed, the potential of the leads 7 and 8 and the electrodes 5 and ₆ is V1, and the potential of the shield 10, which is a floating electrode, is _V2 .
When the degree of vacuum is good, V ₁ > V ₂ holds true. However, when the degree of vacuum deteriorates and glow discharge begins,
When V ₁ > V ₂ becomes V ₁ =V ₂ , the discharge stops, but when it returns to V ₁ >V ₂ , discharge occurs again, and this state is repeated.

Since the potential of V ₂ is determined by the surrounding capacitance, it discharges when the degree of vacuum deteriorates even when the contact is closed, just as when the contact is open. In the same vacuum state, if the distance between the leads 7, 8 and the shield 10 is longer than that between the electrodes in region B, the discharge occurs first between the leads and the shield, so that the sensitivity of vacuum deterioration detection is improved.

In addition, according to the above embodiment, even in a tank-type vacuum switch, it is possible to prevent the vacuum switch from deteriorating when the vacuum switch or disconnector is opened without any work to remove insulating media such as oil or gas. According to the law, a discharge occurs between the electrodes. Detecting the discharge signal at this time,
If the detection signal is electrically processed, vacuum deterioration can be reliably detected. Therefore, when detecting vacuum deterioration, there is no need to remove the vacuum shield or disconnector from the circuit, and there is no need to change the structure of the vacuum shield or disconnector or install a separate high-voltage power supply, making it simple and inexpensive. It is possible to accurately detect vacuum deterioration.

According to the vacuum level monitoring device in each of the above-mentioned embodiments, it can be applied to vacuum shields and disconnectors that are already in use, and can be applied to most models, including those that are completely earth-shielded. Deterioration of vacuum level can be detected in live line condition. Also,
A commercial power source or a battery may be used as a power source for the detection unit, which is compact and convenient to carry. Note that the detection sensitivity for vacuum deterioration is greater when the discharge gap is larger, allowing detection even in high vacuum, and the pressure value at the time of vacuum deterioration is approximately from the 10 ^-3 Torr level to the 100 Torr level.

As described above, according to the present invention, a signal that is discharged when the vacuum level of a vacuum circuit breaker in a metal casing kept at ground potential is degraded is transmitted to a voltage detecting terminal provided on the casing or Detection is performed using a nearby detection object, and the detection signal is displayed on an oscilloscope via a bandpass filter, making it possible to reliably detect vacuum deterioration in the vacuum chamber or disconnector inside the housing, as well as detect external Sensitive detection is possible without being affected by electrical noise. In addition, deterioration of the vacuum level can be detected without removing the vacuum shield or disconnector from the circuit, and there is no need to change the structure of the vacuum shield or disconnector or install a separate high-voltage power supply, making it easy and inexpensive. Can detect vacuum deterioration.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional front view of the vacuum shield breaker, Figure 2 is an electrical equivalent circuit diagram of the vacuum shield breaker in Figure 1 in the shielded state, and Figures 3 and 4 are the vacuum shield breaker. An operating waveform diagram of the disconnector, FIG. 5 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 6 is an explanatory diagram showing details of the voltage detection terminal and the detection section, and FIGS. 7 and 8 A and B. 9 is a waveform diagram, and FIG. 9 is a characteristic diagram showing a pattern curve. 1... Vacuum shield disconnector, 51, 52, 54... First, second, third tank, 53c, 53d... Connection conductor, 56... Capacitor combination, 57... Voltage detection terminal, 59... ...probe, 24,60...bandpass filter, 16...antenna.

Claims (1)

[Claims] 1 A metal casing kept at ground potential, a vacuum breaker placed inside the casing that generates an internal glow discharge when the internal vacuum level deteriorates, and a vacuum breaker connected to the vacuum breaker. A voltage detection terminal led out of the housing via a capacitor combination on the power supply side of the high voltage conductor, and a probe that is placed in contact with or in close proximity to this voltage detection terminal and detects an electromagnetic wave signal generated by the internal glow discharge. a detection body consisting of a bandpass filter that is electrically connected to the detection body and passes only frequency components from 2KHz to 20KHz;
A vacuum level monitoring device for a vacuum shield and disconnector, characterized by comprising an oscilloscope connected to the output of the filter and displaying only the frequency components that have passed through the filter.