The high-voltage circuit breaker is an important component of the power system. Xiao Bian analyzes the fault diagnosis of the high-voltage circuit breaker by failing to close the case, and shares the troubleshooting method and experience of the high-voltage circuit breaker failing to close the fault. Great help.
High voltage circuit breaker can not be closed case 1
Faulty equipment: A 10kV high voltage switchgear.
Symptom: This high voltage cabinet is used to control a 10kV overhead line. After the line is overhauled, it is ready to be turned on and off. When the microcomputer sends a closing command, the circuit breaker has a continuous "close-trip" phenomenon, causing the power transmission time to be delayed for several hours, resulting in economic losses for the user.
Diagnostic analysis:
1 Check the DC operating power supply, in good condition.
2 Check the closing contactor, intermediate relay, connecting wire, and no abnormality was found. And the closing contactor has been activated.
3 Check the operating mechanism of the circuit breaker and find that the bracket and the roller shaft are too small to be eaten, which causes the closing mechanism to be unable to hang and fall off, and the closing position cannot be maintained.
Troubleshooting: After adjusting the closing mechanism, the fault is eliminated.
[Experience summary]: If the circuit breaker jumps when it is closed, the common cause is insufficient battery voltage, damage of silicon rectifier component, premature disconnection of auxiliary normally closed contact of circuit breaker, adhesion of relay contact, position of operating mechanism The adjustment is incorrect and so on.
High voltage circuit breaker can not be closed case 2
Faulty equipment: A 10kV high voltage switchgear.
Fault phenomenon: During the closing operation, there is a failure phenomenon that cannot be electrically closed.
Diagnostic analysis:
1 Manual operation can be closed normally, which means that there is no problem with the mechanical transmission components.
2 Check the closing control circuit, relays, closing coils, auxiliary contacts, connecting wires, etc., all in good condition.
3 The failure of the circuit breaker closing failure, in addition to the operating mechanism and electrical circuit failure, the problem of operating the power supply can not be ignored. The closing power supply for this circuit breaker is a DC battery pack that has been in operation for several years and has been found to have a severe drop in battery voltage a few months ago.
4 Measure the closing bus voltage to 215V, the voltage does not seem to be low. However, this is a no-load voltage. When the switch is closed, the inrush current is very large, reaching 100A or more. If the battery pack is faulty, the internal resistance of the power supply will increase, resulting in a significant drop in the terminal voltage.
5 After the actual measurement, at the moment of closing, the terminal voltage of the battery pack is less than 100V. At this time, although the closing iron core can move, but the electromagnetic force is not enough, the mechanism is not lifted, and the circuit breaker cannot be closed.
Troubleshooting: Replace the defective battery.
[Experience Summary]: In a substation using a DC operating power supply, a maintenance-free battery pack should be used. It is also necessary to regularly check the maintenance-free battery and repair or replace the battery that does not meet the requirements in time to ensure the normal operation of the operating system.
High voltage circuit breaker can not be closed case 3
Faulty equipment: 5# high voltage switchgear (10kV, used to control 1600kV.A power transformer) in a company substation.
Fault phenomenon: The duty electrician performs power transmission operation on the 5# high voltage cabinet according to the dispatcher's order. During the closing process of the circuit breaker, a huge sound of “嘣†was heard in the switch cabinet, and the closing operation failed.
Diagnostic analysis:
1 The circuit breaker is a ZN28-10 hand truck type vacuum circuit breaker. Pull out the handcart for inspection. At this time, the actual mechanical position of the circuit breaker is displayed as the opening position, but in the electrical interval display device, it is shown that the C-phase circuit is still in the charging state.
2 Check the appearance of the vacuum interrupter. Through the glass casing, it can be seen that the A-phase and B-phase vacuum arc-extinguishing chambers are normal, the shields and other components are clean and bright, and the surface of the shields inside the C-phase arc extinguishing chamber is black, and there are obvious burning marks and heavy decline.
3 The AC voltage withstand test was carried out on the three phases of the circuit breaker. It was found that both the A phase and the B phase can meet the specification requirements (42 kV/min), and when the C phase test voltage rises to 3 kV, the vacuum interrupter is broken.
4 The power industry standard clearly stipulates that: at the end of the allowable storage period of the vacuum circuit breaker, the gas pressure inside the vacuum interrupter shall not exceed 6.6×102Pa; when the vacuum interrupter is shipped with the vacuum circuit breaker, the gas pressure inside the vacuum interrupter shall not be allowed. More than 1.33 × 102Pa. The vacuum degree of the circuit breaker is detected by a vacuum tester. The phase A is 4×102Pa, the phase B is 3.4×102Pa, and the phase C is 5×102Pa. This indicates that the vacuum of the power transformer of the C-phase arc extinguishing chamber has basically failed. .
Troubleshooting: Replace the C-phase vacuum circuit breaker.
[Experience Summary]: Vacuum circuit breaker is a circuit breaker with vacuum as the medium and arc extinguishing means. It is an important control and protection appliance in the power system. If there are faults and defects, it will not be able to control and protect, and even cause grid failures and personal accidents. Therefore, it is necessary to observe and inspect the vacuum degree and insulation performance of the vacuum circuit breaker regularly or irregularly, and to replace the vacuum interrupter that has reached the service life or has an abnormal phenomenon in time.