JPH05325744A - Vacuum circuit breaker - Google Patents

Abstract

PURPOSE:To provide a safe vacuum circuit breaker with CR surge absorber in which no charge is left in a CR surge absorber when a vacuum switch and the CR surge absorber are separated and pulled out from a circuit. CONSTITUTION:On a truck 1 loaded with a vacuum switch 3 and a CR surge absorber 5, a contact 25 is provided in parallel to the CR surge absorber 5. A grounding electrode 27 is provided in a position such that the contact 25 is grounded when the truck 1 is pulled out. When the truck 1 is pulled out, the charge of the surge absorber 5 is surely discharged, and safety is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for preventing electric shock in a vacuum circuit breaker equipped with a surge absorber for suppressing a switching surge.

[0002]

2. Description of the Related Art As an example of a conventional vacuum circuit breaker, Japanese Patent Laid-Open No.
The structure of a vacuum circuit breaker similar to that shown in 62-140325 is shown in FIG. In the figure, 1 is a truck, 2 is an insulator mounted on the truck 1, 3 is a vacuum switch supported by the insulator 2, 4 is a load side terminal connected to one side of the vacuum switch 3, 5 Is a surge absorber connected to the load side terminal 4, and 6 is a ground wire, which is connected to the other side of the surge absorber 5. Reference numeral 7 is a power supply side terminal connected to the other side of the vacuum switch 3, and 8 is an insulating operation rod connected to the vacuum switch 3.

Reference numeral 9 is a stroke conversion lever connected to the insulating operation rod 8, 10 is a driving contact spring connected to the stroke conversion lever 9, 11 is an opening / closing lever connected to the driving contact spring 10, and 12 is an opening / closing. A drive shaft for driving the lever 11, 16 is a power source contact fixed to the power source side terminal 7, 17
Is a load contact fixed to the load side terminal 4,
18 is a wall surface made of insulating material for the circuit breaker that houses the truck 1.
Reference numeral 19 denotes a movable contact of the vacuum switch 3, which is provided at the tip of the insulating operation rod 8.

The insulating operating rod 8, the stroke converting lever 9, the contact spring 10 and the opening / closing lever 11 are connected to each other by a rotatable pin.

For the convenience of explaining the operation of the vacuum circuit breaker of FIG. 7, its internal connection and connection with a load are shown in FIG. Figure 8
Indicates the case of using for a single phase. In the figure, 3 to 7, 16 to 17 and 19 are the same as in FIG. Although not shown in FIG. 7, 20 is a load device connected to the load contactor 17, 21 is a fuse inserted in series in the circuit inside the load device 20, and 22 is a load circuit element. The load device 20 is composed of a fuse 21 and a load circuit element 22. There are various types of surge absorbers 5 which will be described later, but the so-called CR
A so-called surge absorber is composed of a capacitor 23 and a resistor 24 connected in series.

Next, the operation will be described. In FIG. 8, since the vacuum circuit breaker generally has excellent current breaking characteristics of the vacuum switch 3, a high surge voltage may be generated when the vacuum switch 3 is opened and closed, causing a failure such as dielectric breakdown in the load 20. In order to reduce this surge voltage, a so-called CR surge absorber, a surge arrester, a ZnO type surge absorber, etc. is used as a load.
It is selected and used in consideration of 20 characteristics and circuit voltage. The present invention relates to the case where a CR surge absorber is used as the surge absorber 5. Figure 8
In the above, two sets of the vacuum switch 3 and the surge absorber 5 are used for single-phase power, but three sets are used in the case of three phases. In rare cases, the surge absorber 5 may be used in parallel with the load 20.

In order to improve the maintainability of the movable part inside the circuit breaker, in particular, the insulating operating rod 8 for moving the movable contact 19 of the vacuum switch 3 is loaded on the easily movable carriage 1. ing. The connection of the power line when pulling out the carriage 1 is automatically connected or disconnected by the movement of the carriage 1 by the power contact 16 and the load contact 17. For convenience of explanation, the position where the cart 1 is pulled out will be referred to as a maintenance position hereinafter.
Further, as shown in FIG. 7, the state in which the carriage 1 is pushed in and the power source side terminal 7 and the load side terminal 4 are securely connected to the power source contactor 16 and the load contactor 17 is called an operating position.

In order to open and close the vacuum switch 3 in FIG. 7, the drive shaft 12 is rotated by rotating the operation handle (not shown) while the carriage 1 is pushed into the operating position. The movement is transmitted to the opening / closing lever 11, the contact spring 10, the stroke conversion lever 9, and the insulating operation rod 8, the insulating operation rod 8 is moved up and down, and the movable contact 19 is opened and closed.

Even when the insulating operating rod 8 is moved up and down, the movable contact 19 and the power source side terminal 7 are connected by a soft electric wire, so that there is no obstacle to the free movement of the movable contact 19. Absent.

If current is flowing through the vacuum switch 3 when the movable contact 19 begins to open, the circuit inductance in the circuit including the power line and the load 20 and surge voltage depending on the breaking performance of the vacuum switch 3 Occurs. Since the circuit inductance is often concentrated on the load 20, most of the above surge voltage occurs across the load 20. Even when the vacuum switch 3 is closed, the movable contact 19 may vibrately contact (so-called chattering) and a surge voltage may be generated.

These surge voltages are held and stored in the capacitors 23 of the two sets of surge absorbers 5 shown in FIG. 8. Normally, the trolley 1 is pulled out after the vacuum switch 3 is opened.
Since it takes time until the load side terminal 4 is disconnected, it is discharged through the load 20 and the charge is stored in the capacitor.
It's never going to be 23. In addition, the movable contact of the vacuum switch 3
Depending on the timing when 19 starts to open, almost no surge voltage may occur. Even in this case, the above 2
Since the power supply voltage was applied to the pair of surge absorbers 5 immediately before the circuit was opened, a part of the power supply voltage is stored in the capacitor 23, but this is also almost the same as after the circuit of the vacuum switch 3 was opened. Unless discharged, it is discharged through the load 20, leaving no charge. When the carriage 1 is pulled out, a mechanism is devised so that the vacuum switch 3 cannot be pulled out unless it is opened.

Next, in the apparatus of FIGS. 7 and 8, after the vacuum switch 3 is opened, the capacitor 23 of the surge absorber 5 is opened.
The case where the electric charge remains in will be described. In FIG. 8, when the vacuum switch 3 is closed and power is being supplied to the load 20, the fuse 21 may be blown out for some reason. In this case, the voltage from the power source is applied to the surge absorber 5 even after the fuse 21 is blown. Vacuum switch 3 in this state
When the circuit is opened, the electric charge stored in the capacitor 23 of the surge absorber 5 immediately before the circuit is opened breaks the discharge path.
It is not discharged and the electric charge remains. If the hand is touched to pull out the trolley 1 and maintain the inside in this state, there is a danger of electric shock, which is dangerous.

9 to 11 show conventional examples in which the surge absorber 5 is used differently from the conventional examples shown in FIGS. 7 and 8. FIG. 9 is an internal structure diagram of a vacuum circuit breaker similar to that shown in Japanese Patent Laid-Open No. 62-140325. In FIG. 9, 1-4, 7-12, 16-19 are the same as the conventional example of FIG. 7, but the load side terminal 4 of the surge absorber 5
The side not connected to is not directly attached to the trolley 1 but is insulated and attached by the insulator 2. Also, the ground wire 6
Unlike FIG. 7, it is not directly connected to the surge absorber 5, but will be described later.

Reference numeral 13 denotes a fixed contact, which is a surge absorber 5
Is provided on the pole on the side not connected to the load side terminal 4. Reference numeral 14 is a movable blade that can come into contact with the fixed contact 13, is grounded by the ground wire 6, and is supported by the carriage 1 by a rotatable pin. A connecting rod 15 connects the opening / closing lever 11 and the movable blade 14. The open / close lever 11, the connecting rod 15, and the movable blade 14 are connected to each other by a rotatable pin.

The internal connection of the vacuum circuit breaker of FIG. 9 and the connection when applied to the single-phase load device 20 are shown in the connection diagram of FIG. The fixed contact 13 and the movable blade 14 are shown as a three-position switch in FIG. 10, and the circuit of the surge absorber 5 lives only at the center of the three positions.

To explain the operation of the vacuum circuit breaker of FIG. 9 in detail, an operation explanatory diagram is shown in FIG. In FIG. 11, the horizontal axis indicates the position of the opening / closing lever 11, the left end is the lowermost position of the opening / closing lever 11, and the right end is the uppermost position of the opening / closing lever 11. Line A shows the open / closed state of the contact of the vacuum switch 3, and shows that the open / closed state of the contact changes at the position of the point C on the horizontal axis. Line B is the connecting rod of the movable blade 14.
It shows the movement of the end part connected to 15, the lowest point at the left end,
At the right end is the highest point. Line D shows the contact state between the movable blade 14 and the fixed contactor 13, which is open at both left and right ends (indicated by L ₁ in the figure) and at the center (indicated by L ₂ in the figure). Indicates that it will be closed.

Now, the vacuum switch 3 is in the closed position, that is, in FIG.
When the opening / closing lever 11 is pushed down from the uppermost position to the lowermost position in order to perform the opening operation from the state of the right end, the movable blade 14 first contacts the fixed contact 13 and the surge absorber 5 Is connected to the circuit, then the vacuum switch 3
The movable contact 19 of the is changed from closed to open, and finally the movable blade 14
Is separated from the fixed contactor 13, and the surge absorber 5 is disconnected from the circuit again.

When the contacts of the vacuum switch 3 are operated from open to closed, the surge absorber 5 is first connected to the circuit, and then the vacuum switch, as in the case of the above-mentioned operation from close to open. The contacts of 3 are closed and then the surge absorber 5 is disconnected from the circuit. In the case of the system shown in FIG. 9, the surge absorber 5 is connected to the circuit only when the vacuum switch 3 is opened and closed, and is disconnected from the circuit while the open or closed state continues.

When the vacuum switch 3 is operated from closed to open before the trolley 1 is pulled out, after the vacuum switch 3 is opened and before the surge absorber 5 is disconnected from the circuit, the surge absorber Whether or not the electric charge stored in 5 is discharged to the load 20 depends on the operation time difference between the vacuum switch 3 and the movable blade 14, and its operation depends on the movable blade 14
Since it is affected by the speed of the manual operation to operate the, the discharge is not always reliable. Also, in the case of the method of FIG. 9 as well, when the load has the fuse 21 as shown in FIG. 8, it is more likely that electric charges remain in the surge absorber 5 after the vacuum switch 3 is opened. .. A method is also known in which a resistor is connected in parallel with the capacitor 23 or the surge absorber 5 to discharge electric charge, but since there is a drawback that a high voltage is applied during operation and the resistor consumes a large amount of power, it is mostly used. It has not been.

[0020]

Since the conventional vacuum circuit breaker is constructed as described above, there is a possibility that electric charges may remain in the surge absorber when the bogie for maintenance is pulled out. It is dangerous to touch a capacitor that has a residual charge, so even if the probability of remaining a charge is low, for safety, take measures such as short-circuiting the surge absorber to discharge it before starting maintenance work on the circuit. It must be done without fail, workability is poor, and there is a risk of electric shock or burns if the procedure is not performed properly.

The present invention has been made in order to solve the above problems, and the electric charge of the surge absorber is surely discharged when the trolley is pulled out, and it is safe to perform no discharge treatment. The purpose is to get a circuit breaker.

[0022]

SUMMARY OF THE INVENTION A vacuum circuit breaker according to the present invention has contacts connected in parallel to a surge absorber including a capacitor loaded on a carriage, and when the carriage is moved, the contacts are opened and closed. It was done.

[0023]

In the vacuum circuit breaker configured as described above, when the carriage is pulled out, the contacts connected in parallel with the surge absorber are closed and the electric charge stored in the capacitor is discharged.

[0024]

【Example】

Example 1. An example in which the circuit breaker having the structure shown in FIG. 7 is implemented as an embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 to 12 and 16 to 19 are the same as in the conventional example of FIG. Reference numeral 25 denotes an electrode mounted on the trolley 1 so as to be insulated by the insulator 2, and is connected to the load side terminal 4 side of the surge absorber 5 by an electric wire 26. 27 is the wall
The grounding electrode is provided so as to project from part of 18 and is grounded. The position of the grounding electrode is an intermediate position between the operating position and the maintenance position of the trolley 1 when the trolley 1 is pulled out, and the power source side terminal 7 and the power source contact. The connection between the child 16 and the load side terminal 4 and the load contact 17 is provided so that the ground electrode 27 contacts the electrode 25 only when the carriage 1 is located at a position where they are completely separated from each other. There is.

FIG. 2 is an internal connection diagram of the vacuum circuit breaker of the embodiment shown in FIG. When the carriage 1 is completely pushed to the operating position, the electrode 25 is not in contact with anything, so that the operation as the vacuum circuit breaker is no different from the conventional case of FIG.

After the vacuum switch 3 is opened, when the truck 1 is pulled out, the connection between the power source contact 16 and the load contact 17 is broken first, and when the truck 1 is further pulled out, the electrode 25 contacts the ground electrode 27. Even if electric charges remain in the surge absorber 5, they are discharged. When the trolley 1 is further pulled out to a maintenance position (not shown in the figure), the contact between the electrode 25 and the ground electrode 27 is cut off again, but the surge absorber 5 is no longer charged, so it is safe. Is. In FIG. 2, the electrode 25 and the ground electrode 27 constitute a so-called NO (normally open) contact switch.

Example 2. FIG. 3 shows the structure of a circuit breaker according to a second embodiment of the present invention. In the figure, 28 is a switch, which is a so-called NC (normally closed) contact, and 29 is an actuator for moving the contact of the switch 28. Reference numeral 30 is a dog provided on the wall 18, and is provided at a position where the contact point of the switch 28 is opened by pushing the actuator 29 only when the carriage 1 is pushed into the operating position. The switch 28 is connected in parallel with both ends of the surge absorber 5 by an electric wire 26. The other structure is similar to that of FIG.

FIG. 4 shows an internal connection diagram of the second embodiment shown in FIG. The relationship between the pull-out position of the carriage 1 and the situation where the actuator 29 is pushed by the dog 30 will be described with reference to FIG. The horizontal axis of FIG. 5 indicates the pull-out position of the truck 1, the right end indicates the operating position of the truck 1, and the left end indicates the maintenance position. A line E is a line showing opening / closing of the switch 28, and a line F is a line showing a contact state between the power source side terminal 7 and the power source contactor 16. From the state where the trolley 1 is pulled out,
When pushed into the operating position, the dog 30 first pushes the actuator 29, the contact of the switch 28 is opened, and the short circuit of the surge absorber 5 is released. Push the trolley 1 further and the dog
Power contact 1 with 30 holding actuator 29
6. The load contact 17 is connected, and the circuit breaker can be used.

At the position where the trolley 1 is pushed into the operating position, the dog 30 pushes the actuator 29 and the contact of the switch 28 is open, so the operation as a vacuum circuit breaker is exactly the same as the conventional example of FIG. .. When the trolley 1 is pulled out, first the power contact 16
When the trolley 1 is pulled out further, the actuator 29 is released from the dog 30 before the trolley 1 reaches the maintenance position, the contacts of the switch 28 are closed, and both ends of the surge absorber 5 are closed. Are short-circuited, and the electric charge stored in the capacitor 23 of the surge absorber 5 is discharged.

In the second embodiment, the surge absorber shown in FIG.
An example in which the present invention is applied to the case where the conventional example shown in FIG. 9 is used has been described, but the present invention can be applied even when the conventional example shown in FIG. 9 is used. Further, the switch in the second embodiment is connected in parallel to the surge absorber, but as shown in FIG. 6, one contact is connected in parallel to the entire two sets of surge absorbers connected in series. Even if it is done, the same effect can be obtained. In the case of three phases, it is sufficient to have two contacts.

In FIGS. 1 and 3, the moving part is called a dolly and is shown with wheels, but it may be a movable frame regardless of the presence or absence of wheels. Further, although the switch is connected to both ends of the surge absorber, the same effect can be obtained even if the switch is connected to both ends of the capacitor. Further, an appropriate resistor may be connected in series with the switch in order to prevent a momentary large current at the time of short circuit discharge.

[0032]

As described above, according to the present invention, the vacuum switch, the surge absorber with a capacitor connected to the vacuum switch, and the surge absorber connected in parallel are provided on the movable frame. Since the contacts are opened and closed when the frame is moved, the charge of the surge absorber is surely discharged when the frame is pulled out.
The effect that it is safe for maintenance work is obtained.

[Brief description of drawings]

FIG. 1 is a structural diagram of a vacuum circuit breaker according to a first embodiment of the present invention.

FIG. 2 is a connection diagram of the vacuum circuit breaker of the first embodiment.

FIG. 3 is a structural diagram of a vacuum circuit breaker according to a second embodiment of the present invention.

FIG. 4 is a connection diagram of a vacuum circuit breaker according to a second embodiment.

FIG. 5 is an operation explanatory view of the vacuum circuit breaker of the second embodiment.

FIG. 6 is a connection diagram of another embodiment.

FIG. 7 is a structural diagram of a conventional vacuum circuit breaker.

8 is a connection diagram of the conventional vacuum circuit breaker of FIG.

FIG. 9 is another structural diagram of a conventional vacuum circuit breaker.

10 is a connection diagram of the conventional vacuum circuit breaker of FIG.

FIG. 11 is an operation explanatory view of the conventional vacuum circuit breaker of FIG. 9.

[Explanation of symbols]

 1 trolley 3 Vacuum switch 5 Surge absorber 23 Capacitor 25 Electrode 27 Ground electrode 28 Switch 29 Actuator 30 Dog

Claims (1)

[Claims] 1. A vacuum switch, a surge absorber including a capacitor connected to the vacuum switch, a contact connected in parallel to the surge absorber, the vacuum switch, the surge absorber and the contact are mounted. A vacuum circuit breaker, comprising: a movable frame body, wherein the contact is opened and closed by the movement of the frame body.