1. The office environment should be considered when choosing an AC contactor. The key is to consider the following factors.
①The AC contactor should be used to control the AC load, and the DC contactor should be used for the DC load
②The rated working current of the main circuit breaker should be higher than or equal to the current of the load power circuit. It should be noted that the rated working current of the main circuit breaker of the AC contactor is the normal working current (rated working standard voltage. Application type. Actual working frequency, etc.). When the specific usage conditions are not used at the same time, the current will also change.
③ The rated working standard voltage of the main circuit breaker should be higher than or equal to the working voltage of the load power circuit.
④ The rated current of the electromagnetic coil should be consistent with the working voltage of the control circuit.
2. Select the operation steps of the AC contactor.
①Select the type of AC contactor, the type of AC contactor must be selected according to the type of load.
②Select the main stability parameters of the AC contactor.
According to the measurement target and main operating parameters, such as working voltage and current, the main operating parameters, such as working voltage, current, output power, working frequency, etc.
(1) The coil voltage of the AC contactor should generally be lower, which can reduce the insulation resistance of the AC contactor and make it safer to use. When the control circuit is simple and the application of household appliances is small, the working voltage of 380V or 220V can be used at the same time. If the power circuit is complicated. When the number of household appliances exceeds 5, electromagnetic coils with 36V or 110V working voltage can be used to ensure safety. However, due to the convenience and speed, the reduction of mechanical equipment is often selected according to the voltage of a specific power grid.
(2) The actual working frequency of the motor is not too high, such as refrigeration compressors, centrifugal pumps, centrifugal fans, central air conditioners, etc. , the rated voltage of the AC contactor may exceed the rated voltage of the load.
(3) Use heavy duty motors whose rated voltage of the AC contactor exceeds the rated voltage of the motor, such as the main motor of CNC lathes, lifting platforms, etc.
(4) Motors for special main purposes. When the AC contactor is turned over, it can be roughly used according to the electrical service life and starting current, CJ10Z.CJ12.
(5) When using the AC contactor to operate the transformer, the current of the surge protector should be considered. For example, DC welding machine, AC contactor, such as CJT1.CJ20, can generally be selected according to twice the rated voltage of the transformer.
(6) The rated voltage of the AC contactor refers to the maximum allowable current of the AC contactor under long-term operation, the duration is ≤8H, and it is assembled on the open controller. If the cooling standard is weak, when using an AC contactor, select the rated voltage of the AC contactor according to 1.1-1.2 times the rated voltage of the load.
(7) Select the total amount and type of AC contactors. The total number and type of circuit breakers should comply with the regulations of the control circuit.
Post time: Jun-21-2022