What is the principle of selection of AC contactor ?

Publish Time:2015-02-05 Author:admin Views:0

The voltage level of AC contactor and load the same, contactor type selection and adapt to load.
(2) to calculate the current load to meet the contactor capacity level, that is to calculate the current less than or equal to the rated working current contactor. Switch the current contactor is greater than the starting current of the load, breaking current is greater than the load running time off need current, load current should be considered in the calculation of actual working environment and conditions, for a long time to start half an hour load, peak current shall not exceed vheating current.
(3) according to the dynamic and thermal stability calibration short. Three phase short-circuit current lines should not exceed the contactor allows dynamic and thermal current, when using the contactor disconnect the short-circuit current, should also check contactor breaking capacity.
(4) contactor attract coil rated voltage, current and auxiliary contact number, current capacity should meet the requirements of the control circuit wiring. To consider the length of the control loop of the contactor is connected in the circuit, the operating voltage is generally recommended values, contactor to 85 ~ 110% of the rated voltage value work. If the line is too long, because the voltage drop is too large, the coil of the contactor is likely to switch on instructions not reflect; because the line capacitance is too large, may have no effect on the trip command.
(5) according to the operating frequency allows the operation times check contactor. If the operating frequency exceeds the specified value, should increase one times rated current.
(6) the parameters of short circuit protection component and contactor with selected parameters should be. The selection can be see sample manual, Handbook of general sample is given table with the contactor and fuse.