the active and static contacts, auxiliary contacts, coils, short-circuit rings, arc-extinguishing covers and other components of

low-voltage plastic case circuit breaker are liable to malfunction. when the equipment fails to trip, it can not be simply closed. it is necessary to check the appearance, arc-extinguishing covers and other components for burnout. if so, the malfunction parts should be removed for inspection, repair or replacement, and the stain wiped clean.
1, high temperature caused circuit breaker tripping
low voltage plastic case circuit breaker installed in outdoor distribution boxes, higher temperature in summer, coupled with load, the temperature in the box will rise, exceeding the suitable working environment of the circuit breaker. overload protection thermal bimetallic elements of circuit breakers are rolled by two metals with different thermal expansion coefficients. when the bimetal senses the heat generated by the overload current, the active layer will bend to the passive layer. if the environment, temperature and temperature around the circuit breaker exceed the reference temperature, even if the passing current is not overloaded, when the normal rated current is less than the rated current, the circuit breaker will bend to the passive layer. action time will be early and overload protection function will be lost. therefore, it is necessary to raise the rated value of circuit breaker, reduce the operating current and conduct on-site heat dissipation treatment.
2. when starting the motor, the circuit breaker trips
1 and starts the motor with load. when the motor starts with load, the current increases and the circuit breaker trips. before starting the motor, check whether the load of the motor is cut off or not, and then start the motor without load.
2, is low voltage, when starting the motor, the current increases sharply, resulting in the increase of starting current and circuit breaker tripping. the range of voltage variation at the client's receiving end should not exceed. the customer of three-phase low-voltage power supply should be rated voltage + 7%-7x. when the voltage measurement value exceeds the prescribed value, measures such as adjusting transformer taps and load should be taken.
3, the setting multiple of instantaneous protection of circuit breaker is too small. reasonable adjustment of instantaneous protection setting multiple of circuit breaker is in line with the operation requirements of field equipment. fourthly, the selected plastic case circuit breaker is not power type, which leads to circuit breaker tripping. correct plastic case circuit breaker should be selected according to the use of equipment.
3. causes and measures of tripping when circuit breakers are in operation.
1, is the choice of connecting cables or copper bars section is too small easy to heat, so that circuit breakers tripping.
2, is the fastening bolt of the load end to tighten, resulting in poor contact and a lot of heat, so that circuit breaker tripping.
3 is load overload tripping.
4. treatment of damage of low voltage plastic case circuit breaker components.
1 is the main and secondary contacts. surface burns should be replaced to avoid excessive grinding and reduce the pressure of the contact surface.
2 is an auxiliary contact. use fine sandpaper (cloth) to polish; the contact surface should not be greasy.
3 is an arc extinguishing cover. carbonization should be scraped clean; damp should be baked; damaged should be re-matched; installation angle should be correct, so as not to hinder contact action.
4 is short circuit loop and coil. damage should be replaced in time.
5 is a soft connector. damaged components should be replaced in time.