Test and precautions of small moulded case circuit breaker

    There are many factory test items, and the main item when the electromagnetic small molded case circuit breaker leaves the factory is the instantaneous characteristic calibration, that is, the disconnection under the short circuit condition and the delay characteristic, that is, the disconnection power frequency withstand voltage test under the overload condition and the national standard level test.

    The instantaneous characteristic is also the goal of calibration. The setting value is plus 20% to minus 20%. The calibrated parts are electromagnetic air gap, reaction spring, etc. the temperature of the environment here also has no influence on the electromagnetic used in any case. If there is a problem in the instantaneous time, the problem can not be summarized to the environment with different temperature.

    Our wiring method is also a series connection of two poles, and each pole acts only once on the line. The instantaneous time calibration table also includes the method of single-phase low-voltage large current, the requirements of the key instruments and meters of the calibration table as well as the requirements of the accuracy, as well as the current transformer, ammeter, voltmeter and timer.

    The adjustment method here is also instructive. Only under constant temperature can we adopt the low-voltage method and then use the high-power current to electrify the test object, and adjust the distance between the bimetallic screws and the release plate on the circuit breaker and make the action time of the circuit breaker reach the specified range of the enterprise.

    In general, the rated breaking capacity of small circuit breaker is tested under the condition that the incoming port of upper terminal and the outgoing port of lower terminal are in the project. If the incoming line of lower terminal or the outgoing line of upper terminal are required under some special circumstances, due to the reason of arc extinction when breaking the fault current, the small molded case circuit breaker must also reduce the capacity In this case, it is necessary to pay attention to that the rated breaking capacity must be converted according to the relevant derating coefficient provided by the manufacturer, which can not be handled at will, which will lead to very serious consequences.

    When our line voltage or load current changes, the output voltage of DC power supply will fluctuate unsteadily. The degree of voltage stabilization is also determined by the parameters of the voltage stabilization circuit and a relatively constant power supply supplied by the power supply requires basic load voltage stabilization. There are also some internal impedances, that is, the internal resistance of the power supply and the load Is not conducive to the load voltage regulator circuit working environment or objects.

    The transient response and recovery time of the power supply indicate the capacity of the power supply voltage stabilizing circuit to recover normal voltage when the output load changes suddenly, and there are two parameters to calibrate. One is that the output deviates when the load changes suddenly, and the other is the time to recover to the original value everywhere Then, in general, when the load changes at 10%, the output deviation is calibrated by using the milli optimal value of the output deviation from the peak voltage, and the recovery time is when the output returns to the normal value.