The utilization category specifies the nominal electrical performance of the contactor referred to a specific type of load. In the IEC / EN60947-4-1 standard, for each utilization category, the test conditions to which the contactor must be subjected to verify its operational effectiveness are prescribed. The most common utilisation categories for contactors are:
- AC-1 Non-inductive or slightly inductive loads (in practice resistance control)
- AC-3 Motor control
See the complete list at the bottom.
For example, if a manufacturer declares that a contactor has an AC-3 rated current of 9A at 400V means that this contactor can control motors with a
maximum rated current of 9A at 400V. The standard requires a long series of tests to confirm the conformity of the product to the control of such motors.
- AC-1 Non-inductive or slightly inductive loads; resistance furnaces
- AC-2 Slip-ring motors: starting, switching off
- AC-3 Squirrel-cage motors: starting, switching off motors during running
- AC-4 Squirrel-cage motors: starting, plugging, inching
- AC-5a Switching of electric discharge lamp controls
- AC-5b Switching of incandescent lamps
- AC-6a Switching of transformers
- AC-6b Switching of capacitor banks
- AC-8a Hermetic refrigerant compresso motor control with manual resetting of overload releases
- AC-8b Hermetic refrigerant compressor motor control with automatic resetting of overload releases
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