Daily Maintenance And Operation Of Low Voltage Circuit Breaker

In addition to the above reasons, there are also the following factors affecting the service life of low-voltage circuit breakers: the service time is too long, resulting in the insulation aging of circuit breakers; Because of the wear between the mechanism and the drying up of the lubricating oil in the circuit breaker, the closing operation of the circuit breaker is impeded and the action characteristics are changed. Due to the breaking of overcurrent (especially short-circuit current), corrosive gas and debris are generated between static and static contacts, which increases the resistance of contacts. As the ambient air temperature rises and the circuit breaker heats up, the insulating parts are heated and deformed, and the movement of the mechanism is hindered. Loose fastening screws of wiring terminals and other components cause abnormal heating and even spark. These reasons do not exist separately, but often together affect the circuit breaker, thus shortening the life of the circuit breaker.
Circuit breaker inspection, for large frame circuit breaker, in addition to the design of the type test, batch production after the manufacturer's regular test, also can refer to the following points:
First, check before power use
Check the packing box of the circuit breaker for transport. There should be no scraps of paper or dust attached to the circuit breaker. Check the connection status of the conductor; Check the pressure resistance and other basic information to make sure there are no problems.
Two, regular inspection
According to the operating environment and working conditions, it is necessary to carry out periodic inspection, pay attention to dust, cleaning work.
Three, low voltage circuit breaker internal inspection should pay attention to matters
When it is necessary to open the cover to check the mechanism and contact system of the circuit breaker, because the insulation partition and arc extinguishing chamber inside the circuit breaker are easy to fall, so after opening the cover to check, it is necessary to carefully count and restore the parts that are easy to fall. For circuit breakers with small shell level current, such as common leakage circuit breakers, etc. There is a seal (or warning plate) between the bottom and the cover, in order not to allow random adjustment of the trip element, so the customer should pay special attention not to move the trip element, otherwise the performance changes, the manufacturer is not responsible.
Iv. Inspection matters and treatment methods of the circuit breaker after short circuit
When the circuit breaker is in general short circuit, its breaking current is often the expected short circuit current value of the small dry line (that is, less than the limit short circuit breaking current of the circuit breaker). This is due to the distance between the short circuit point and the power supply, the line impedance of the short circuit point and the rated voltage of the circuit breaker compared with the actual line voltage there is a certain margin caused by the differences in factors.
For short circuit current less than the rated operating short circuit breaking capacity of the circuit breaker, after breaking, can still be used. However, if the circuit breaker is broken at the rated limit of short circuit current or with a cascade (back-up) protection for that adverse condition, the circuit breaker damage is much greater. In the actual operation of short circuit current breaking, when the short circuit current is broken, after the short circuit accident is removed, it is also necessary to close the circuit breaker (even if the rated short circuit current is broken), but after breaking the same value of short circuit current again, the circuit breaker must be replaced.