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Influence Of Ambient Temperature On Circuit Breaker Characteristics
Sep 27, 2017

  Influence of Ambient Temperature on Circuit Breaker Characteristics

  Circuit breaker is the most widely used distribution system, the largest amount of one of the distribution of electrical appliances. Customers generally concerned about the use of different types of circuit breakers in different places of use, the conditions should be how to derailment. For example, the circuit breaker is installed in a set of electrical appliances (switchgear, box), due to a variety of electrical appliances (knife switch (or load switch), contactors, circuit breakers, connecting copper, etc.). One of the issues to be considered, one is the impact of ambient temperature on the characteristics of the circuit breaker.

  1 plastic housing circuit breakers

  From the current domestic and international market sales of plastic shell-type circuit breakers, there are all electromagnetic type (commonly known as oil cup release), a hot-type electromagnetic release and electronic release and microprocessor trip And other types.

  1) Electromagnetic type oil cup release is used for overload long delay, but also for short-circuit current instantaneous protection (ie overload and short circuit protection using the same oil cup release). Overload long delay protection delay, by the oil cup in the reaction of the spring and the methyl silicone oil to damp the floating core of the move (when the oil cup within the floating core in the high current, do not have to float can be off Remove the armature of the armor, so that the circuit breaker trip).

  2) with the largest number of hot-type electromagnetic type. It is overloaded with a long delay using hot bimetallic components, short-circuit current when the instantaneous use of electromagnet system. Different manufacturers, in the use of the instructions or samples on the use of the circuit breaker to reduce the use of current and environmental temperature of the table, or temperature and current curve, known as the temperature compensation curve.

  3) Overcurrent protection circuit breakers for household or similar use. The circuit breaker conforms to the standard is GB10963, which is different from the 1), 2) class (in line with GB14048.2) is the reference check temperature is 30 degrees (of course, as the protection of household appliances, its overload long delay and short circuit Dynamic protection of the characteristics are not the same).

  2 universal (frame) type circuit breaker

  1) universal circuit breaker, the derating and molded shell of the thermal-electromagnetic type is basically the same. Other universal circuit breakers, such as SRW45 universal circuit breakers as well.

  2) Electronic release (including microprocessor trip)

  Electronic and microprocessor release are more used in universal (frame) circuit breakers, the current large current specifications of the plastic shell circuit breaker, the circuit breaker is used in industrial electronic components, to adapt to the ambient temperature The range is wide (-40-85), that is, in this temperature range, the performance of electronic components will not change. Analysis of the reasons: changes in ambient temperature, no impact on the performance of electronic components. High current specifications to derailment because the wiring copper in the high current heat caused by the overall rise in temperature. For low-voltage electrical appliances, the ambient temperature within 10-40 within the circuit breaker temperature basically no effect, and more than 40 have an impact, the extent of the impact is not.

  In summary, the ambient temperature exceeds the reference temperature of the circuit breaker check, the circuit breaker installed in the switch cabinet needs to reduce the use of current value, the value of the rated current multiplied by the derating factor. The maximum ambient temperature (box, cabinet environment) allowed by the current set is different depending on the type and quantity of the internal electrical components. The user shall use this maximum permissible ambient temperature, for example, 50, 55 or 60, and derive from the current-temperature relationship table or temperature compensation factor provided by the circuit breaker manufacturer.