JPH0736308B2 - Vacuum switch - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a vacuum switch, and more particularly to detection of a vacuum defect.

[Technical background of the invention and its problems] As is well known, a vacuum switch is small and lightweight, capable of high-speed shutoff, has little damage to contacts, has a long service life, does not generate noise when opening and closing, and has a flame and Since it has excellent properties such as no danger of explosion, it is used over a wide range.

As shown in FIG. 4, this vacuum switch is formed by providing end plates 3 and 4 at both ends of an insulating container 2 in which a vacuum container 1 has a cylindrical shape. A fixed energizing shaft 5 that is airtightly fixed to the end plate, and a movable energizing shaft 7 that is movably attached to the end plate 4 through a bellows 6 without breaking the vacuum are disposed. Axis 7
Contact points 5a and 7a that can be freely attached to and detached from the opposite ends of the
Is provided. Further, the insulating container 2 is formed in a cylindrical shape so as to surround the contacts 5a and 7a, and the metal vapor generated in the current switch of the contacts 5a and 7a adheres to the inner surface of the insulating container 2 and the dielectric strength of the insulating container 2 is increased. The shield 8 is provided to prevent the deterioration of the temperature.

On the other hand, since the above-mentioned characteristics of the vacuum switch have a great influence on the degree of vacuum in the vacuum container 2, it is necessary to detect the decrease in the degree of vacuum, and various vacuum defect detecting devices have been put to practical use or proposed. ing. As an example of this, a vacuum defect detecting device to which an elastic wave is applied is shown in FIG. That is, the vacuum defect detecting device 9 is composed of a ground electrode 10 provided on the surface of the insulating container 2 and an elastic wave detector 11 provided close to the ground electrode 10. When the vacuum container 1 becomes defective in vacuum, discharge is likely to occur between the shield 8 and the current-carrying part composed of the fixed current-carrying shaft 5, the movable current-carrying shaft 7, the contacts 5a and 7a, and the shield. 8 to 5 compared to the case without the ground electrode 10
It is supposed to be changed by%. Then, when a vacuum defect occurs, a discharge is generated between the current-carrying part and the shield 8, and an elastic wave is generated by this discharge. This is detected by the elastic wave detector 11, and the amplifier 12 It is displayed on the display device 13 via.

By the way, in order to detect the elastic wave accurately, the elastic wave detector 11 must be in close contact with the surface of the insulating container 2. However, it is considerably difficult to maintain the same adhesion on the surface of the insulating container 2 of the vacuum switch, which is manufactured in a large amount, for a long period of time for the reason described below. Become.

(1) The insulating container 2 is cylindrical and has a curvature, and the manufacturing tolerance of the outer diameter is considerably large.

(2) Due to the shock caused by the opening / closing operation, the adhered portion is easily peeled off.

(3) An adhesive is used for the close contact portion, but it deteriorates with age due to the adhesive ability of the adhesive, the usage environment, and the like.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vacuum switch equipped with a vacuum defect detection device that facilitates manufacture and prevents deterioration of detection accuracy. And

SUMMARY OF THE INVENTION The present invention is a vacuum switch in which end plates are provided at both ends of an insulating container to form a vacuum container, and a pair of contacts that can be freely contacted and separated from each other is provided inside the vacuum container. The ground electrode is placed close to the outer peripheral surface of the container, and the center is close to the outer peripheral surface of the insulating container so that the angle between the center of the vacuum container and the center of the ground electrode is 30 ° <330 °. To ensure that the detector is in close contact with the insulating container by providing a vacuum defect detection device that includes a detector that detects the pulsed discharge that occurs between the ground electrode and the current-carrying part in the vacuum container. This makes it possible to detect a vacuum defect without being affected by the manufacturing tolerance of the outer diameter of the insulating container, which facilitates the manufacture and prevents the detection accuracy from deteriorating.

[Embodiment of the Invention] An embodiment of a vacuum switch according to the present invention will be described below with reference to the drawings. The same parts as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 1, a vacuum defect detection device 20 is provided with a search coil 21 arranged close to the insulating container 2 and having an inductance of about 2 mH, an amplifier 22 for amplifying the detection value of the search coil 12, a counter 23, and a discrimination device 24. And display device 13
It consists of

Thus, the vacuum defect detecting device 20 configured as described above
Is the angle formed by the center lines of the ground electrode 10 and the search coil 21 with respect to the center 25 of the vacuum chamber 1 as shown in FIG.
Then, the ground electrode 10 and the search coil 21 are arranged so that this θ is 30 ° <θ <330 °.

Next, the operation of the present invention configured as above will be described. When the degree of vacuum of the vacuum container 1 is lowered, the dielectric strength of the interior is lowered, and a current-carrying part formed by the fixed energizing shaft 5, the contacts 5a, 7a and the movable energizing shaft 7, the shield 8 and the insulating container 2 are used to connect the ground electrode. Between 10 and 10, a pulsed discharge known as so-called ozonizer discharge occurs. A voltage is induced in the search coil 21 by the change in current due to this discharge, and this is displayed on the display device 13 via the amplifier 22, the counter 23, and the discrimination device 24. Therefore, when the counter 23 and the discriminator 24 open and close the current even when the vacuum switch is normal, part of the current flows through the shield 8 and the ground electrode 10, and at this time, a voltage is induced in the search coil 21. To be done. However, the arc time between the contacts 5a, 7a in this case is only about 1 cycle, so the search coil
The voltage induced in 21 disappears after that time. Therefore, if the integration time of the counter 23 is set to be sufficiently long, the determination device 24 can determine whether the vacuum switch is normal or the vacuum is defective, depending on the number of discharges.

Further, when the search coil 21 is arranged close to the ground voltage 10, the change in the magnetic flux density is small in the vicinity of the ground electrode 10 and the voltage induced in the search coil 21 is low, which makes it difficult to detect the pulse. According to the experiments by the present inventors, the ground electrode 10
Assuming that the arrangement angle of the search coil 21 with respect to the above is θ, as shown in FIG. 3, 0 <θ <30 °, 330 ° <θ <3
It was found that the detection sensitivity of the search coil 21 was significantly reduced in the range of 60 °. Therefore, if this range is avoided, a vacuum defect with good detection sensitivity can be detected. Note that dN / d in the figure
t indicates the number of pulses per unit time (second). The pressure in the vacuum container 1 was 5 × 10 ^-2 torr, and the applied voltage was 4.2 KV.

With this configuration, even if the manufacturing tolerance of the outer diameter of the vacuum container 1 is considerably large, it is not directly affected by it, and since there is no contact portion, there is no peeling or deterioration over time due to the use environment. Further, since the positional relationship is selected so that the detection sensitivity is also good, the vacuum defect can be detected easily and accurately.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it is easy to manufacture, and it is possible to always maintain good detection accuracy and accurately detect a vacuum defect.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of a vacuum switch according to the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1 as seen in the direction of the arrow, and FIG. FIG. 4 is a characteristic diagram of the detection sensitivity of one embodiment, and FIG. 4 is a sectional view showing the structure of a conventional vacuum switch. 1 ... vacuum container, 2 ... insulation container 5 ... fixed energizing shaft, 7 ... movable energizing shaft 10 ... grounding electrode, 13 ... display device 20 ... vacuum defect detection device, 21 ... search coil

Claims (2)

[Claims] 1. A vacuum switch in which end plates are provided at both ends of an insulating container to form a vacuum container, and a pair of contact points which are freely contactable and separable are arranged inside the vacuum container. The ground electrode is disposed in close proximity to, and the angle formed by the center of the vacuum container and the center of the ground electrode is
The center of the insulating container is arranged close to the outer peripheral surface of the insulating container so that 30 ° <330 °, and the pulsed discharge generated between the ground electrode and the current-carrying part in the vacuum container is detected. A vacuum switch which is provided with a vacuum defect detection device including a detector. 2. The vacuum switch according to claim 1, wherein the detector of the vacuum defect detecting device is a search coil.