Effect of ambient temperature on circuit breaker characteristics

Update date:2018-01-03 Source:MAXGE

The circuit breaker is one of the most widely used and used power distribution appliances in the distribution system. Customers are generally concerned about how different types of circuit breakers should be reduced in different places of use. For example, the circuit breaker is installed in a complete set of electrical appliances (switch cabinet, box), due to a variety of appliances knife switch (or load switch), contactor, circuit breaker, connecting copper platoon, etc. One of the things to consider is the impact of ambient temperature on the characteristics of the circuit breakers.

1  Moulded case circuit breaker

      In view of the large number of plastic shell circuit breakers sold in domestic and foreign markets, there are all kinds of electromagnetic type, heat and electromagnetic release and electronic tripping device and microprocessor release device.


1) the maximum number of USES is a thermal electromagnetic type. Its overload length is delayed by using the thermo-bimetallic element, and the electric magnetic system is adopted when short circuit current is used. Different manufacturers, in the specification or samples to the reduced capacity of the circuit breaker to use current relations with the environment temperature form, or expressed in the curve of temperature and current, called the curve of temperature compensation.


2) use current protection circuit breakers for household or similar sites. Circuit breaker is accord with the standard GB10963 it with (1), (2) class (meet GB14048.2) different benchmark calibration temperature 30 degrees, (of course, as the protection of household appliances, its short-circuit transient overload long time delay and the characteristics of dynamic protection is not the same).

2 universal (frame) circuit breaker


Electronic and microprocessor trip more use in universal type, frame type circuit breaker, the large current specifications of plastic shell type circuit breaker, the breaker is used in the electronic components used in industry, to adapt to the environment temperature range is wide (40-85), namely in the temperature range, the performance of the electronic components will not change. Analysis: changes in ambient temperature have no effect on the performance of electronic components. The large current specification should be reduced because the heating caused by the copper wire in the high current caused the whole temperature rise. In the case of low-voltage electrical appliances, the temperature of the circuit breaker has no effect on the temperature of the circuit breaker within 10-40 years, and the influence of over 40 is not significant.


When the ambient temperature exceeds the benchmark temperature of the circuit breaker characteristics, the circuit breaker is installed in the switch cabinet and needs to be appropriately reduced in the use of the current value, which is the rated current times the drop factor. According to the type and quantity of electrical components in the unit, the maximum ambient temperature (box, cabinet environment) allowed by current will be different. The user should use this maximum allowable ambient temperature, such as 50, 55 or 60, to reduce the volume of the condenser according to the current temperature relationship table or temperature compensation factor provided by the circuit breaker manufacturer.

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