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1、circuit breaker "refuse to close" fault

the circuit breaker refuses to close, that is, the circuit breaker automatically opens again as soon as it is closed, making the circuit breaker unable to operate normally.

1、determining the cause and treatment method of "refuse to close" of the circuit breaker can generally be divided into the following three steps.

1）use the control switch to close it again to check whether the previous refusal to close was caused by improper operation (such as letting go of the control switch too quickly, etc.).

2）check the condition of each part of the electrical circuit to determine whether there is a fault in the electrical circuit.

the method is:

①check whether the closing control power supply is normal;

②check whether the closing control circuit fuse and closing fuse are in good condition;

③check whether the contacts of the closing contactor are normal (such as electromagnetic operating mechanism);

④move the control switch plate to the "closing" position and check whether the closing iron core moves (the inspection of hydraulic mechanism, pneumatic mechanism and spring mechanism is similar). if the closing iron core operates normally, it means that the electrical circuit is normal.

3、if the electrical circuit is normal but the circuit breaker still cannot be closed, it means there is a mechanical failure. the circuit breaker should be disabled and reported to the relevant leader to arrange for maintenance. after the above preliminary inspection, it can be determined whether the fault is electrical or mechanical.

2、common electrical circuit faults and mechanical faults are described below.

1>、common electrical faults.

(1)electrical circuit faults may include: if neither the red nor green indicator light comes on before the closing operation, it means that the control circuit is disconnected or there is no control power supply. you can check whether the control power supply and the components on the entire control loop are normal, such as: whether the operating voltage is normal, whether the fuse is blown, whether the anti-trip relay is normal, whether the auxiliary contact of the circuit breaker is good, whether there is air pressure, hydraulic locking, etc.

(2)when the red light does not light up after the operation is closed, the green light flashes and the accident horn sounds, it means that the position of the operating handle does not correspond to the position of the circuit breaker, and the circuit breaker is not closed. common reasons include:

①the fuse of the closing circuit fuse is blown or has poor contact;

②the closing contactor does not act;

③the closing coil is faulty.

(3)when the circuit breaker is closed, the green light goes out and the red light comes on, but instantly the red light goes out and the green light flashes, and the accident horn sounds, indicating that the circuit breaker automatically trips again after closing. the reason may be that the circuit breaker is closed on the faulty line, causing the protective action to trip, or the mechanical failure of the circuit breaker cannot keep the circuit breaker in the closed state.

(4)if the green light goes out and the red light does not light up after closing, but there is an indication on the ammeter, it means the circuit breaker has been closed. possible reasons are poor contact of the circuit breaker auxiliary contacts or control switch contacts, or the tripping coil is disconnected and the circuit is blocked, or the control circuit fuse is blown, or the indicator light bulb is damaged.

(5)the operating handle returns too early.

(6)the dc power supply of the opening circuit is grounded at two points.

(7)SF6 the gas pressure of the circuit breaker is too low, and the density relay blocks the operating circuit.

(8)the pressure of the hydraulic mechanism is lower than the specified value, and the closing circuit is blocked.

2>、common mechanical failures.

(1)the connecting rod of the transmission mechanism becomes loose and falls off;

(2)the closing iron core is stuck;

(3)after the circuit breaker is opened, the mechanism does not return to the pre-closed position;

(4)the tripping mechanism tripped;

(5)the operating voltage of the closing electromagnet is too high, preventing the first-level closing valve from opening;

(6)the closing spring of the spring operating mechanism does not store energy;

(7)the opening connecting rod does not return;

(8)the opening lock hook is not hooked or the adjustment of the opening four-bar linkage mechanism does not cross the dead point, so the closing cannot be maintained;

(9)the mechanism is stuck, and the connecting part's shaft pin falls off, causing the mechanism to close empty;

(10)sometimes when the circuit breaker is closed, it performs multiple closing and opening actions continuously. at this time, the auxiliary breaking contact of the switch opens too early.