The load properties and current changes during on-off process of different electrical equipment vary greatly, so the requirements for contactors are also different. GB/T 14048.1 standard specifies the use categories of contactors, which are characterized by one or more of the following use conditions:
● Current, expressed as a multiple of rated current
● Voltage, expressed as a multiple of rated working voltage
● Power factor or time constant
● Short circuit performance
● Other conditions of use (if applicable)
The main application categories of HC6 series AC contactors are as follows:
Use category of AC main circuit
This category applies to all AC loads with a power factor greater than or equal to 0.95.
For example: heating, power distribution.
This category is applied to the starting, reverse braking and inching of slip ring motor.
When closed, the contactor turns on the starting current, which is about 2.5 times the rated current of the motor.
When disconnected, the contactor must disconnect the starting current when the voltage is less than or equal to the main power supply.
This category shall be used to disconnect normally started squirrel cage motors.
When closed, the contactor turns on the starting current, which is about 7 times the rated current of the motor.
During disconnection, the contactor disconnects the rated current of the motor. At this time, the voltage at the terminal of the contactor is
about 20% of the main power supply, and the disconnection is not severe.
For example: all standard squirrel cage motors: vertical ladder, escalator, conveyor belt, excavator, air compressor, pump, mixer, air
This category includes reverse braking and inching of squirrel cage motor and slip ring motor.
The contactor connects 5 to 7 times the rated motor current, breaks the same current under higher voltage, and the motor speed is lower.
At this time, the voltage is the same as the main voltage, and the breaking is very severe.
For example: printing machinery, wire drawing machine, tower crane, hoisting, metallurgical industry.
Use category of control circuit
The working system shall be used for starting, reverse current braking and inching of DC shunt motor. Duration ≤ 2 ms.
This category applies to switching electromagnetic loads.
This category is applied to switching electromagnetic loads. When the electromagnet is closed, the pull-in power is greater than 72 VA.
Example: operating coil of switch contactor