Vacuum breaker common fault analysis and treatment

This paper starts with the common faults in the operation of vacuum circuit breakers, performs fault analysis and provides processing methods, hoping to increase the user's technical accumulation of vacuum circuit breakers.

Common high-voltage vacuum circuit breaker failure analysis and treatment The advantages of vacuum circuit breaker are not only oil-free equipment, but also its long electrical life, mechanical life, breaking insulation capacity, continuous breaking capacity, The utility model has the advantages of small volume, light weight, frequent operation, no fire, low operation and maintenance, and the like, and is quickly recognized by the operation, maintenance and technical personnel of the electric power department. The quality of the high-voltage vacuum circuit breakers produced in the early stage was not stable enough. During the operation, the current-carrying voltage was too high, and some vacuum interrupters still had air leakage. By the time of the Tianjin Vacuum Switch Application Promotion Conference in 1992, the manufacturing technology of vacuum circuit breakers in China has entered the forefront of the same type of products in the same industry in the world, and has become a new turning point in the application and manufacturing technology of high-voltage vacuum circuit breakers in China. With the widespread use of vacuum circuit breakers, fault conditions sometimes occur.

1. Circuit breaker rejection and rejection

It is shown that after the circuit breaker is closed (open) command, the closing (opening) electromagnet acts, the iron core ejector will close (open) the scorpion top open, and the closing (opening) spring releases energy. Drive the circuit breaker to close (open), but the circuit breaker arc extinguishing chamber can not be closed (open).

2, circuit breaker misclassification

It is manifested that the circuit breaker is in normal operation and trips under unexplained conditions.

3. After the circuit breaker mechanism stores energy, the energy storage motor does not stop.

It is shown that after the circuit breaker is closed, the operating mechanism of the operating mechanism starts to work, but after the spring energy is full, the motor is still running.

4, the DC resistance of the circuit breaker increases

It is shown that after the circuit breaker is running for a certain period of time, the contact resistance of the arc-extinguishing chamber contacts is continuously increased.

5, the circuit breaker closing bounce time increases

It is shown that after the circuit breaker is running for a certain period of time, the closing bounce time is increasing.

6, the circuit breaker intermediate box CT surface discharge to the bracket

It is shown that during the operation of the circuit breaker, the surface of the current transformer discharges to the intermediate box bracket.

7, the circuit breaker arc chamber can not be disconnected

It is manifested that after the circuit breaker performs the opening operation, the circuit breaker cannot be disconnected or not completely disconnected.

1, circuit breaker refused to distinguish, refused

When the operating mechanism is refused, it is generally first analyzed whether the reason for the rejection is a secondary circuit failure or a mechanical partial failure, and then processed. After checking that the secondary circuit is normal, it is found that the universal joint head connected to the main arm of the operating mechanism is too large. Although the operating mechanism operates normally, it cannot drive the breaker to close and close the link, resulting in the breaker not being able to divide normally. Closing.

2, circuit breaker misclassification

Under normal operating conditions, the circuit breaker cannot be opened when there is no external operating power supply and mechanical opening action. When it is confirmed that no erroneous operation has been performed, the secondary circuit and the operating mechanism are inspected. It is found that the auxiliary switch contact in the operating mechanism box has a short circuit phenomenon, and the opening power supply is connected to the opening coil through the short circuit point, thereby causing a false opening. The reason is that the top of the circuit breaker mechanism box leaks rain, and the rainwater flows down the output arm, which falls on the mechanism auxiliary switch, causing the contact to be short-circuited.

3. After the circuit breaker mechanism stores energy, the energy storage motor does not stop.

After the circuit breaker is closed, the operating mechanism of the operating mechanism starts to work, and after the spring energy is full, the spring has stored energy signal. In the energy storage circuit, there are a pair of normally open auxiliary contacts and a pair of normally closed contacts of the circuit breaker. After the circuit breaker is closed, the normally open contacts of the auxiliary switch are turned on, the energy storage motor starts to work, and the spring is full of energy. The mechanism rocker arm opens the normally closed contact of the travel switch, the energy storage circuit is de-energized, and the energy storage motor stops working. The reason why the energy storage motor has been working all the time is that after the spring is full of energy, the mechanism rocker arm fails to open the normally closed contact point of the travel switch, the energy storage circuit is always charged, and the energy storage motor cannot stop working.

4, the DC resistance of the circuit breaker increases

Since the contacts of the vacuum interrupter are butt joints, the contact resistance of the contacts is too large. The contacts are prone to heat during current carrying, which is not conducive to conduction and breaking circuits, so the contact resistance value must be less than the requirements of the factory specification. The pressure of the contact spring has a great influence on the contact resistance and must be measured with an overtravel pass. The gradual increase in contact resistance also reflects the electrical wear of the contacts and is complementary. The electrical wear of the contact and the change of the contact opening distance of the circuit breaker are the root causes of the increase of the DC resistance of the circuit breaker.

5, the circuit breaker closing bounce time increases

When the vacuum circuit breaker is closed, the contacts always bounce, but if it is too large, the contacts are easily burned or welded. The technical standard for the bounce time of the vacuum circuit breaker contact is ≤ 2ms. As the running time of the circuit breaker increases, the main cause of the increase in the closing bounce time is the spring force drop of the contact spring and the wear of the arm and shaft pin gap.

6, the circuit breaker intermediate box CT surface discharge to the bracket

The current transformer is installed in the middle box of the circuit breaker. When the circuit breaker is running, the surface of the current transformer will produce an uneven electric field. To avoid this phenomenon, the transformer manufacturer coats the surface of the transformer with a layer of semiconductor glue, which makes the surface electric field uniform. . During the assembly process of the circuit breaker, due to the space limitation, the semiconductor glue around the transformer fixing bolt is scraped off, and the uneven electric field on the surface of the transformer in the operation of the circuit breaker causes the surface of the transformer to discharge to the bracket.

7, the circuit breaker arc chamber can not be disconnected

Under normal conditions, whether it is a manual opening operation or a protection action trip, the circuit breaker can effectively open the circuit and cut off the current. The principle of arc extinguishing of vacuum circuit breakers and other types, the superiority of vacuum circuit breakers is not only oil-free equipment, but also its long electrical life, mechanical life, breaking insulation capacity, continuous breaking ability The utility model has the advantages of small volume, light weight, frequent operation, no fire, low operation and maintenance, and the like, and is quickly operated, repaired and technicians by the electric power department.

The circuit breaker is different, which refers to the switch device that the contact is closed and opened in the vacuum, that is, the circuit breaker that uses vacuum as the insulation and arc extinguishing medium. The vacuum degree of the vacuum bubble is lowered, and there is a certain ionization phenomenon in the vacuum bubble, and thus electric ions are generated, so that the insulation in the arc extinguishing chamber is lowered, and the circuit breaker cannot be normally broken.

1. Circuit breaker rejection and rejection

Check the clearance of all connected parts of the operating mechanism, and replace the new high-hardness qualified parts with the defective parts.

2, circuit breaker misclassification

Check all possible leaks and perform effective sealing; install a sealing rubber sleeve on the output arm link; open the heating device in the mechanism box.

3. After the circuit breaker mechanism stores energy, the energy storage motor does not stop.

Adjust the position of the travel switch so that the normally closed contact of the travel switch can be opened when the rocker is at the highest position.

4, the DC resistance of the circuit breaker increases

Adjust the contact opening distance and overtravel of the arc extinguishing chamber. The method of measuring the contact resistance can be measured by the DC voltage drop method required by the “Procedure” (current should be above 100A), otherwise the arc extinguishing chamber should be replaced.

5, the circuit breaker closing bounce time increases

(1) Appropriately increase the initial pressure of the contact spring or replace the contact spring.

(2) If the arm and shaft pin clearance exceeds 0.3mm, the arm and shaft pin can be replaced.

(3) Adjusting the transmission mechanism, using the characteristics that the transmission ratio is small when the closing position exceeds the dead point of the active arm, the mechanism is adjusted toward the dead point, which can reduce the contact closing bounce.

6, the circuit breaker intermediate box CT surface discharge to the bracket

Apply a layer of semiconductor glue evenly on the surface of the transformer to make the surface electric field uniform.

7, the circuit breaker arc chamber can not be disconnected

For the treatment of the vacuum interrupter that does not reach the required vacuum value, if the vacuum of the vacuum interrupter is detected to have fallen below the required value, the vacuum interrupter should be replaced. Specific steps

(1) The vacuum interrupter to be replaced shall pass the vacuum test.

(2) Remove the original vacuum interrupter and replace it with a new vacuum interrupter. Be vertical when installing. Pay attention to the coaxiality of the moving rod and the arc extinguishing chamber, and should not be subjected to torque during operation.

(3) After installing the new vacuum interrupter, measure the opening distance and overtravel (contact stroke). If it does not meet the requirements, it should be adjusted accordingly: 1 Adjust the bolt of the insulation rod to adjust the overtravel; 2 Adjust the length of the movable rod to adjust the opening distance of the arc chamber.

(4) Use the power switch comprehensive tester to measure the mechanical characteristics such as closing speed, three-phase synchronization, closing bounce, etc. If it is unqualified, it should be adjusted.

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