JP5183763B2 - Tank type vacuum circuit breaker - Google Patents

Description

  The present invention relates to a tank-type vacuum circuit breaker suitable for detecting a decrease in the degree of vacuum of a vacuum interrupter by detecting a discharge phenomenon caused by needle-like electrodes.

  Conventionally, a tank type vacuum circuit breaker 100 of 72 kV class or higher (hereinafter referred to as “vacuum circuit breaker 100”) is provided in an external tank 110 filled with low-pressure SF6 gas or high-pressure dry air as shown in FIG. The ceramic vacuum interrupter 120 is housed.

  Here, the external tank 110 is grounded and has a ground potential.

  The vacuum interrupter 120 includes a fixed electrode 122a and a movable electrode 122b accommodated in a cylindrical ceramic casing 121. Both ends of the ceramic casing 121 are sealed with a conductive fixed metal plug 123a and a movable metal plug 123b. Yes.

The fixed electrode 122a is directly connected to the fixed-side metal plug 123a via the fixed-side main circuit conductor 124a, and an external fixed-side main circuit (not shown) is connected to the fixed-side metal via the fixed-side main circuit conductor 124a. It is directly connected to the stopper 123a.
A conductor through-hole for penetrating the movable side main circuit conductor 124b is formed in the center of the movable side metal plug 123b, and an external movable side main circuit (not shown) is the movable side main circuit conductor 124b. Is directly connected to the movable electrode 122b.

  Since the conductor through hole is formed in the movable side metal plug 123b, the inside of the ceramic casing 121 is kept in a vacuum by the interrupter bellows 125. The movable metal plug 123b is electrically connected to the movable main circuit conductor 124b through the interrupter bellows 125.

In the ceramic housing 121, the fixed electrode 122a and the movable electrode 122b are covered with an interrupter internal shield 126 that is electrically connected to the movable metal plug 123b, so that the electric field gradient at the center of the vacuum interrupter 120 is moderated. .
Further, both ends of the vacuum interrupter 120 are covered with the fixed shield 130a and the movable shield 130b, so that the electric field gradients at both ends of the vacuum interrupter 120 are made gentle.

The fixed-side metal plug 123a, the fixed-side main circuit conductor 124a, and the fixed-side shield 130a are made of a metal material (such as an aluminum or copper conductor and silver-plated), and are electrically at the same potential.
Similarly, the movable-side metal plug 123b, the movable-side main circuit conductor 124b, and the movable-side shield 130b are made of a metal material and are electrically at the same potential.

  In the vacuum circuit breaker 100 configured in this way, since the vacuum interrupter 120 is housed in the external tank 110 and cannot be visually observed from the outside, it is not possible to easily determine a malfunction (breakage or the like) of the vacuum interrupter 120. .

  Further, when the vacuum of the vacuum interrupter 120 is broken, the interruption performance of the vacuum circuit breaker 100 is lost, so that even the normal load current cannot be interrupted. Therefore, it is important to grasp the degree of vacuum of the vacuum interrupter 120, and an apparatus for detecting a decrease in the degree of vacuum of the vacuum interrupter 120 in an operating state is set as an option.

  Patent Document 1 listed below does not require a power failure and high-voltage power supply device for checking the degree of vacuum, makes it easy to determine the degree of vacuum, and reduces the cost of maintenance work, etc. A detector that detects the spectrum of arc light generated between the contacts in the vacuum valve at times and outputs an electrical signal, and the degree of vacuum decreases when the spectrum shows the emission line spectrum of the insulating gas based on the electrical signal There is disclosed a vacuum circuit breaker monitoring device for a vacuum circuit breaker, which is provided with a signal processing circuit unit for determining this and outputting an alarm signal, and the signal processing circuit unit is installed in a non-contact relationship with the main circuit.

  In Patent Document 2 below, the wall surface of the vacuum circuit breaker is designed so that it is not necessary to take a power outage for investigating the degree of vacuum of the vacuum valve, and no high voltage power supply device is required, and the degree of vacuum is always easily monitored. An opening is provided in a part of this, and a sealing terminal in which an antenna is resin-sealed is attached to the opening so that the output terminal is led out from the resin surface and airtightly attached from the outside, and the voltage of the main circuit is applied to the vacuum valve. In this state, the electromagnetic wave in the microwave band released by the discharge generated inside the vacuum valve when the vacuum level in the vacuum valve drops below a predetermined value is detected, and only the signal generated by the vacuum level reduction is detected from this electromagnetic wave signal. A vacuum provided with a signal processing circuit section that outputs an output signal for operating a lock function for stopping the electrical switching operation of the circuit breaker that has been sorted and outputs an alarm according to this sorting signal and the degree of vacuum reduction has occurred Monitoring apparatus is disclosed.

JP-A-8-306279 JP-A-7-318447

However, since a vacuum monitoring device is not generally installed in the vacuum circuit breaker 100, even if the vacuum interrupter 120 breaks down in a vacuum, it is not until a test voltage is applied between the opening of the vacuum circuit breaker 100 during periodic inspection. In addition to the fact that the vacuum break was revealed, there was a problem that even if the vacuum circuit breaker 100 was interrupted in this state, it could not be interrupted.
In addition, there is a possibility that the main body of the vacuum interrupter 120 may be destroyed by performing a normal opening operation even if the accident is not interrupted, and in the worst case, there is a problem that the power system may be completely interrupted. .

A device that can detect a decrease in the degree of vacuum in the operating state detects a discharge phenomenon from the vacuum interrupter 120 that occurs at the point where the withstand voltage between the opening is minimized (the bottom of the Paschen curve) in the process of decreasing the degree of vacuum. Although it is a method for judging a decrease, there is a possibility that it cannot be detected when the vacuum breaker 100 is in a stopped state (a state in which no power is applied), and there is a possibility that it cannot be detected (that is, the degree of vacuum is lowered in a state in which a voltage is applied) If the voltage is applied in a state where the degree of vacuum is reduced, there is a possibility that it cannot be detected).
In addition, the device for monitoring the degree of vacuum reduction in the operating state is expensive and has a problem that the device needs to be updated every 10 to 15 years because the device is an electronic device.

  An object of the present invention is to provide a tank-type vacuum circuit breaker capable of detecting a decrease in vacuum even in an operating state and capable of detecting a decrease in vacuum and outputting an alarm in real time.

The tank-type vacuum circuit breaker according to the present invention has a fixed side in which a vacuum interrupter (20) is housed in an external tank (10) having a ground potential, and covers the end of the vacuum interrupter on the fixed electrode (22a) side. A tank-type vacuum circuit breaker (1) having a shield (30a), which is attached to an outer surface of a fixed-side metal plug (23a) for sealing the end of the fixed electrode side of the ceramic casing (21) of the vacuum interrupter. In addition, when the degree of vacuum in the ceramic body is lowered, the degree-of-vacuum detecting device (40) includes a needle-like electrode (41) that protrudes from the stationary shield and generates electric discharge between the outer tank and the external tank. ) And a discharge detection antenna (51) for detecting a discharge generated between the external tank and the needle-like electrode and attached to the vacuum circuit breaker. To.
Here, the degree-of-vacuum detection device may be made of a conductive material, and the needle-like electrode may be electrically connected to the fixed electrode via the fixed-side metal plug.
A through hole for communication for communicating the ceramic body and the inside of the vacuum level lowering detection device is formed in the fixed side metal plug, and the tip of the needle electrode protrudes from the fixed side shield. Needle-like electrode protruding holes may be formed.
The vacuum degree reduction detecting device includes a bellows case (43) in which a communication hole connected to the communication through-hole is formed in a bellows base forming a bottom surface, and a lower end fixed to an inner surface of the bellows base and an upper end A vacuum degree detecting bellows (44) fixed to a plate-like piston stopper (46) and forming a bellows space communicating with the ceramic housing together with the bellows base and the piston stopper; A bellows expansion / contraction spring (45) mounted between the lowering detection bellows and the side surface of the bellows case and extending the vacuum degree lowering detection bellows, and provided between the needle electrode and the piston plug And one end is always pressed against the piston plug, and the vacuum reduction detection bellows is substantially perpendicular to the expansion and contraction direction of the bellows. The Jo electrode A, and a bell crank for moving linearly (47).
The vacuum degree reduction detecting device includes a needle-like electrode mounting member (41b) to which the other end of the bell clamp is attached and a distal end of the needle-like electrode is fixed, and a distal end of the needle-like electrode. A needle-shaped electrode adjustment nut (41a) for adjusting the amount of protrusion of the tip of the needle-shaped electrode from the fixed-side shield by changing a portion to be fixed to the needle-shaped electrode mounting member may be further provided.
The discharge detection antenna is installed between the needle-like electrode projecting hole formed in the fixed-side shield and the external tank, and the external tank is a portable type installed outside the external tank. An antenna connection terminal for connecting the discharge detection antenna to the discharge detection device (52) may be formed.
The discharge detection antenna may be installed at a lower end portion of a main circuit bushing provided in the tank-type vacuum circuit breaker.

The tank type vacuum circuit breaker of the present invention has the following effects.
(1) Degree of vacuum reduction can be detected in the operating state It is possible to detect the degree of vacuum reduction in the operating state, and it is possible to detect the degree of vacuum reduction and output the alarm in real time by always installing the vacuum degree detecting device.
(2) Possible to eliminate the need to install expensive and short-lived discharge detectors in units of vacuum circuit breakers. The discharge detector is portable, and malfunctions such as inspections, simple inspections, and accident interruptions are expected. By adopting a method of connecting only when it is performed, it is not necessary to install a discharge detecting device having a high cost and a short life in units of vacuum circuit breakers, and the cost can be reduced.
(3) Detection is possible even when the vacuum interrupter is completely ruptured. This is not a method of detecting the moment when the vacuum interrupter ruptures, but the moment when it passes through the bottom part of Paschen. Since this is a method for detecting a decrease in the degree of vacuum, detection is possible even when the vacuum circuit breaker having a reduced degree of vacuum is recharged.
(4) The same life as the vacuum breaker body of the vacuum level drop detection device is possible. The vacuum level drop detection device is a mechanical device, so there are few factors that deteriorate over time due to use. Repair can be made unnecessary until the end of its service life.
(5) Applicable to existing vacuum circuit breaker By replacing the vacuum interrupter of the existing vacuum circuit breaker with a vacuum interrupter having needle-like electrodes by fine inspection etc., it is possible to detect a decrease in the degree of vacuum.

It is a figure for demonstrating the structure of the tank type vacuum circuit breaker 1 by one Example of this invention. It is a figure for demonstrating the structure of the vacuum degree fall detection apparatus 40 shown in FIG. It is a figure which shows the state of the vacuum degree fall detection apparatus 40 at the time of the vacuum break of the vacuum interrupter 20 shown in FIG. It is a graph which shows the relationship of the gap distance versus voltage between electrodes (a needle | hook vs. flat plate electrode) with a large electric field gradient. It is a figure for demonstrating the discharge at the time of the vacuum holding of the vacuum interrupter 20 shown in FIG. 1, and a vacuum break. It is a figure which shows the structure of the conventional vacuum circuit breaker 100. FIG.

  For the above purpose, a vacuum degree reduction detecting device having a needle-like electrode that generates a discharge between the tip and the external tank when the degree of vacuum in the ceramic body of the vacuum interrupter is lowered is generated. It was realized by attaching the discharge detection antenna for detecting the discharge generated between the external tank and the needle electrode to the vacuum circuit breaker, as well as attaching to the outer surface of the fixed metal plug that seals the end on the fixed electrode side.

Embodiments of a tank-type vacuum circuit breaker according to the present invention will be described below with reference to the drawings.
A tank-type vacuum circuit breaker 1 (hereinafter referred to as “vacuum circuit breaker 1”) according to an embodiment of the present invention has the following points as shown in FIG. Different from the vessel 100.
(1) A vacuum level drop detecting device 40 for detecting a vacuum level drop in the ceramic housing 21 is fixed to the outer surface of the fixed side metal plug 23a (the surface opposite to the fixed side electrode 22a).
(2) The through-hole for communication for connecting the inside of the ceramic housing 21 and the inside of the vacuum degree fall detection apparatus 40 is formed in the stationary side metal plug 23a.
(3) The fixed shield 30a is formed with a needle-like electrode projecting hole for projecting the tip of the needle-like electrode 41 (see FIG. 2) of the vacuum degree reduction detecting device 40.
(4) The discharge detection antenna 51 is attached below the needle-like electrode protruding hole formed in the fixed-side shield 30a. An antenna connection terminal for connecting the discharge detection antenna 51 to the portable discharge detection device 52 is attached to the lower surface of the external tank 10.

  In the following description, the inner diameter of the external tank 10 is 500 mm, the outer diameters of the fixed shield 30a and the movable shield 30b are 300 mm, and the distance between the outer tank 10 and the fixed shield 30a (conductive portion) is 100 mm. Further, the distance between the main circuit grounds of the vacuum circuit breaker 1 differs depending on whether the internal gas of the external tank 10 is low pressure SF6 gas or high pressure dry air, and also differs in the electric field design. To do.

  As shown in FIG. 2, the vacuum drop detection device 40 includes a needle electrode 41, a needle electrode guide 42, a bellows case 43, a vacuum degree drop detection bellows 44, a bellows expansion / contraction spring 45, and a piston plug 46. The bell crank 47 is provided.

The bellows case 43 has a hollow columnar shape, and a communication hole connected to the communication through hole of the fixed-side metal plug 23a is formed at the center of the bellows base forming the bottom surface of the bellows case 43.
The lower end of the cylindrical vacuum drop detection bellows 44 is welded to the inner surface of the bellows base (the surface facing the piston plug 46), and the upper end of the vacuum drop detection bellows 44 is a disc-shaped piston plug 46. It is welded to the inner surface (surface facing the bellows base).
As a result, the space surrounded by the bellows base of the bellows case 43, the vacuum degree detection bellows 44, and the piston plug 46 (hereinafter referred to as “bellows space”) is the communication hole of the bellows base and the fixed-side metal plug 23a. It communicates with the inside of the ceramic housing 21 through the communication through hole, and is maintained at the same pressure as the pressure inside the ceramic housing 21.
Therefore, when the vacuum interrupter 20 is kept in a vacuum, the bellows space of the vacuum degree reduction detecting device 40 is also in a vacuum state. On the other hand, the vacuum of the vacuum interrupter 20 is broken and the inside of the ceramic housing 21 is kept. If the pressure is the same as the pressure in the external tank 10, the pressure in the bellows space of the vacuum level drop detection device 40 is also the same as the pressure in the external tank 10.

A bellows expansion / contraction spring 45 having an upper end fixed to the inner surface of the piston plug 46 and a lower end fixed to the inner surface of the bellows base is attached between the vacuum degree reduction detection bellows 44 and the side surface of the bellows case 43.
Thereby, stress is always applied to the vacuum degree reduction detection bellows 44 in a direction in which the vacuum degree reduction detection bellows 44 is extended by the bellows expansion and contraction spring 45.

  The upper end of the bellows case 43 is fixed by a case upper plug having a hole into which the lower end of the bell crank 47 (the end on the piston plug 46 side) can enter, and the piston plug 46 does not extend beyond a certain extent by the bellows expansion and contraction spring 45. It has a structure.

  A spring (not shown) is attached to the rotation center portion (shaft portion) of the bell crank 47, and a force is applied in the direction in which the lower end of the bell crank 47 is always pressed against the piston plug 46 (the direction in which the needle electrode 41 is retracted). ing.

The needle-shaped electrode guide 42 has a hollow rectangular parallelepiped shape, and the end portion is attached to the case upper plug of the bellows case 43.
A needle-like electrode guide hole for passing the tip of the needle-like electrode 41 is formed on the tip surface of the needle-like electrode guide 42.
The rotation center portion and the upper end portion of the bell crank 47 are accommodated in the end portion of the needle electrode guide 42, and the upper end portion of the bell crank 47 is attached to the end portion of the needle electrode mounting member 41b. .
The distal end portion of the needle electrode 41 is attached to the needle electrode attachment member 41b by being fastened by a needle electrode adjustment nut 41a provided on the distal end surface of the needle electrode attachment member 41b.
Thereby, when the vacuum degree decrease detection bellows 44 is expanded and contracted, the tip of the needle electrode 41 can be linearly moved in a direction substantially perpendicular to the expansion and contraction direction of the vacuum degree decrease detection bellows 44 via the bell crank 47. Thus, when the vacuum degree reduction detection bellows 44 is contracted, the tip of the needle electrode 41 can be prevented from protruding from the fixed shield 30a as shown in FIG. When the detection bellows 44 is extended, the tip of the needle electrode 41 protrudes from the fixed shield 30a as shown in FIG. 1B (the amount of protrusion of the tip of the needle electrode 41 from the fixed shield 30a is It can be adjusted by changing the location where the needle electrode 41 is fixed by the needle electrode adjustment nut 41a.

Note that the degree-of-vacuum detection device 40 is made of a conductive material (such as aluminum). Moreover, the vacuum degree fall detection apparatus 40 is attached to the lower part of the outer surface of the stationary-side metal plug 23a.
Therefore, the needle-like electrode 41 has the same potential as the fixed-side metal plug 23a (fixed electrode 22a), and the discharge current is also minute, so a dedicated conductor (such as a flexible conductor) is not necessary.

The discharge detection device 52 is portable and can be connected to the discharge detection antenna 51 via an antenna connection terminal attached to the lower surface of the external tank 10.
As a result, the vacuum degree of the vacuum circuit breaker 1 is reduced, and the tip of the needle electrode 41 of the vacuum degree reduction detecting device 40 protrudes from the fixed shield 30a, and a discharge is generated between the needle electrode 41 and the external tank 10. Then, since this discharge generation can be detected by the discharge detection device 52, the vacuum degree drop of the vacuum interrupter 20 can be detected in real time.
Further, the discharge detection device 52 is provided with alarm generating means for emitting an alarm lamp or sounding an alarm sound when a discharge between the needle-like electrode 41 and the external tank 10 is detected, so that the degree of vacuum of the vacuum interrupter 20 is increased. A drop alarm can be output.

Next, the operation of the vacuum degree reduction detection bellows 44 will be described.
In the following, the pressure in the external tank 10 is about 1.2 kg / cm ² when the internal gas of the external tank 10 is low pressure SF6 gas, and when the internal gas of the external tank 10 is high pressure dry air. Is about 6 kg / cm ² , and therefore, when the vacuum interrupter 20 is reduced in vacuum degree, the low-pressure SF6 gas in which the vacuum degree reduction detection bellows 44 is difficult to extend (spring force = 5 kg).
In addition, the force (pressure) for contracting the bellows expansion / contraction spring 45 is a pressure to the outside of the entire vacuum degree decrease detection bellows 44, but for simplicity of explanation, the pressure applied to the vacuum degree decrease detection bellows 44 is The description will be made using the surface area of the upper surface of the vacuum lowering detection bellows 44.

If the diameter of the vacuum degree reduction detection bellows 44 is 28 mm, the surface area of the upper surface of the vacuum degree reduction detection bellows 44 is about 6 cm ² . Further, since the pressure in the external tank 10 is 1.2 kg / cm ² , the pressure difference applied to the upper surface of the vacuum degree detection bellows 44 is 1.2 kg / cm ² + atmospheric pressure (1 kg / cm ² ) = 2. 2 kg / cm ² .
For this reason, the force for contracting the bellows expansion / contraction spring 45 is 2.2 kg / cm ² × 6 cm ² = 13.2 kg, which is 5 kg or more, which is the spring force of the bellows expansion / contraction spring 45. It is in a compressed state.
Actually, the pressure applied to the side surface of the bellows expansion / contraction spring 45 also acts in the direction in which the bellows expansion / contraction spring 45 is contracted, and therefore the bellows expansion / contraction spring 45 does not extend when the vacuum of the vacuum interrupter 20 is maintained. Further, when the inside of the external tank 10 is high-pressure dry air, the pressure in the external tank 10 is as high as about 6 kg / cm ^2, so that the bellows expansion / contraction spring 45 is compressed with a large force.

When the vacuum of the vacuum interrupter 20 is broken, the pressure in the external tank 10 and the pressure in the ceramic housing 21 become the same pressure. For this reason, since the pressure in the vacuum degree reduction detection bellows 44 is the same as the pressure in the external tank 10, the spring compressive force due to the pressure difference is eliminated, and the vacuum degree reduction detection is performed with 5 kg which is the spring force of the bellows expansion and contraction spring 45. The bellows 44 extends and the piston plug 46 is pushed up to the upper end of the bellows case 43.
As a result, the bell crank 47 rotates in the right direction in FIG. 2 to project the tip of the needle electrode 41 from the fixed shield 30a.

Next, the discharge of the needle electrode 41 will be described.
In the case of an electrode with a gentle electric field gradient, such as a flat plate to flat plate electrode, when a voltage is applied between the electrodes, if the voltage exceeds a certain voltage, the direct spark discharge does not shift from the glow discharge to the spark discharge. It occurs and shifts to arc discharge. However, in the case of an electrode with a large electric field gradient such as a needle-to-plate electrode, when the voltage between the electrodes is increased, the medium at the tip of the needle is ionized and a dark current (μA order) that is a minute current flows. It was generally well known that when it first became glow corona (fluorescence) and further increased in voltage, it changed from brush corona (fluorescence) to streamer corona (ladder), eventually becoming a spark discharge and progressing to an arc discharge. It is a phenomenon.

FIG. 4 shows the relationship between the gap distance and voltage between electrodes (needle vs. flat plate electrode) having a large electric field gradient.
In the case of the 66 kV vacuum circuit breaker 1, the maximum voltage (peak value) applied between the main circuit grounds is 66 kV / 3 ^1/2 × 2 ^1/2 ≈54 kV. In this case, it is understood that an insulation distance of about 6 cm or more is necessary in order not to shift to the spark discharge with the needle-to-plate electrode. Further, since the distance between the main circuit (inner shield) and the ground of the vacuum circuit breaker 1 according to the present embodiment is 100 mm (10 cm) when the vacuum is maintained, it can be seen that a spark discharge occurs when it is about 70 kV or more.
In the graph of FIG. 4, the insulating medium is air and the pressure is atmospheric pressure. When the pressure of the insulating medium increases, the voltage leading to spark discharge increases, but the partial discharge (such as glow discharge) is large. It is also common that there is no change (such as a large increase in withstand voltage).

Next, discharge during vacuum holding will be described by taking as an example a vacuum circuit breaker using high-pressure dry air as an insulating medium.
FIG. 5A shows a state where the vacuum of the vacuum interrupter 20 is maintained and the tip of the needle electrode 41 does not protrude from the fixed shield 30a.
In this state, the positional relationship between the fixed-side shield 30a (inner shield) that is the main circuit potential and the outer tank 10 that is the ground potential is a concentric positional relationship, and is an equal electric field similar to that of the plate-to-plate electrode. This shows that it has a generally known withstand voltage value (withstand voltage of 30 kV / 1 cm) and has a withstand voltage of 300 kV or more. In fact, the withstand voltage performance is improved by optimizing the electric field gradient by carrying out detailed structural design by the manufacturer, and it is designed to withstand a higher lightning impulse (350 kV).

Next, the discharge at the time of vacuum break will be described.
FIG. 5B shows a state in which the vacuum of the vacuum interrupter 20 is broken and the tip of the needle electrode 41 protrudes from the fixed shield 30a.
In this state, since the tip of the needle-like electrode 41 protrudes from the fixed shield 30a, the relationship between the needle-like electrode 41 and the external tank 10 (between the electrodes) is the same as the needle-to-plate electrode. The distance between the main circuit grounds is 90 mm, and the glow discharge starts from the graph of FIG. 4 at about 10 kV. In this state (distance between grounds of 90 mm), a streamer corona (ladder) is generated, and it can be seen that partial discharge is surely generated.

Next, application to an actual vacuum circuit breaker will be described.
Although the above description has been given as an example of a vacuum circuit breaker, actually, a circuit breaker manufacturer is attempting to reduce the size by carrying out detailed structural design and electric field analysis including an external tank and a shield part. Further, even if partial discharge detection does not progress to partial discharge such as glow discharge, a discharge phenomenon can be detected in a dark current state.
The vacuum level drop detection device 40 of the vacuum circuit breaker 1 according to the present embodiment is intended to detect a vacuum break of the vacuum interrupter 20 by capturing a discharge phenomenon, and it can be said that it is desirable to make the partial discharge as small as possible. . For this reason, by adjusting the protrusion amount of the tip of the needle-like electrode 41 that can detect partial discharge according to the circuit breaker design and structure design, the adverse effect on the vacuum circuit breaker 1 given by the vacuum degree decrease detection device 40 (In other words, if the amount of discharge from the needle electrode 41 when the degree of vacuum is reduced is large, a ground fault may occur from the needle electrode 41 toward the external tank 10 during lightning intrusion. In other words, it is necessary to maintain the specified withstand voltage performance by setting the discharge amount to a minimum that allows discharge detection).
It is clear from the above explanation that the discharge that can be detected by the discharge detection device 52 from the needle electrode 41 can be surely generated when the vacuum degree of the vacuum interrupter 20 is lowered by adopting the vacuum degree reduction detection device 40.

  In the above description, the discharge detection antenna 51 is installed on the lower surface of the external tank 10, but the lower end of the main circuit bushing (one attached to each end of the upper surface of the external tank 10) provided in the vacuum circuit breaker 1. The discharge detection antenna 51 may be installed in the part. Even in this case, the sensitivity is lowered, but the degree of vacuum of the vacuum interrupter 20 can be detected.

1,100 Vacuum circuit breaker 10, 110 External tank 20, 120 Vacuum interrupter 21, 121 Ceramic housing 22a, 122a Fixed electrode 22b, 122b Movable electrode 23a, 123a Fixed metal plug 23b, 123b Movable metal plug 24a, 124a Fixed side Main circuit conductors 24b, 124b Movable side main circuit conductors 25, 125 Interrupter bellows 26, 126 Interrupter inner shields 30a, 130a Fixed side shields 30b, 130b Movable side shield 40 Vacuum drop detector 41 Needle electrode 41a Needle electrode adjustment nut 41b Needle-shaped electrode mounting member 42 Needle-shaped electrode guide 43 Bellows case 44 Degree of vacuum detection bellows 45 Bellows telescopic spring 46 Piston plug 47 Bell crank 51 Discharge detection antenna 52 Discharge detection device

Claims (7)

A tank-type vacuum in which a vacuum interrupter (20) is housed in an external tank (10) having a ground potential and has a fixed shield (30a) covering an end of the vacuum interrupter on the fixed electrode (22a) side. A circuit breaker (1),
Attached to the outer surface of the fixed metal plug (23a) for sealing the fixed electrode side end of the ceramic case (21) of the vacuum interrupter, and when the degree of vacuum in the ceramic case is reduced, the fixed side shield A degree-of-vacuum detection device (40) provided with a needle-like electrode (41) for generating a discharge between the tip and the external tank;
A discharge detection antenna (51) attached to the vacuum circuit breaker and for detecting a discharge generated between the external tank and the needle electrode;
A tank-type vacuum circuit breaker comprising: The degree-of-vacuum detection device is made of a conductive material,
The needle electrode is electrically connected to the fixed electrode via the fixed metal plug;
The tank-type vacuum circuit breaker according to claim 1, wherein: A through-hole for communication for communicating the ceramic body and the inside of the vacuum level lowering detection device is formed in the fixed-side metal plug,
A needle-like electrode projecting hole for projecting the tip of the needle-like electrode is formed on the fixed-side shield,
The tank-type vacuum circuit breaker according to claim 1 or 2, characterized by the above. The degree-of-vacuum detection device is
A bellows case (43) in which a communication hole connected to the communication through hole is formed in a bellows base forming a bottom surface;
In order to form a bellows space having a lower end fixed to the inner surface of the bellows base and an upper end fixed to a plate-like piston plug (46) and communicating with the ceramic casing together with the bellows base and the piston plug. The vacuum degree detection bellows (44) of
A bellows expansion / contraction spring (45) attached between the vacuum degree reduction detection bellows and a side surface of the bellows case and for extending the vacuum degree reduction detection bellows;
The needle electrode is provided between the needle electrode and the piston plug, and one end is always pressed against the piston plug, and the needle electrode is arranged in a direction substantially perpendicular to the expansion and contraction direction of the vacuum degree detection bellows. A bell crank (47) for linear movement;
The tank-type vacuum circuit breaker according to any one of claims 1 to 3, further comprising: The degree-of-vacuum detection device is
A needle electrode mounting member (41b) to which the other end of the bell clamp is attached, and a terminal portion of the needle electrode is fixed;
A needle-like electrode adjustment nut (41a) for adjusting the amount of protrusion of the tip of the needle-like electrode from the fixed-side shield by changing the location where the end of the needle-like electrode is fixed to the needle-like electrode mounting member When,
The tank-type vacuum circuit breaker according to claim 4, further comprising: The discharge detection antenna is installed between the needle-like electrode protruding hole formed in the fixed-side shield and the external tank,
An antenna connection terminal for connecting the discharge detection antenna to a portable discharge detection device (52) installed outside the external tank is formed in the external tank.
The tank-type vacuum circuit breaker according to any one of claims 3 to 5, wherein   6. The tank-type vacuum circuit breaker according to claim 1, wherein the discharge detection antenna is installed at a lower end portion of a main circuit bushing provided in the tank-type vacuum circuit breaker.

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