Page 432 - Motor_protection_and_control_Manual_motor_starters_ contactors

4-pole contactors

Electrical durability and utilization categories

General
Utilization categories determine the current making and breaking conditions relating to the characteristics of the loads to be
controlled by the contactors. International standard IEC 60947-4-1 and European standard EN 60947-4-1 are the standards to
be referred to.
If Ic is the current to be broken by the contactor and Ie the rated operational current normally drawn by the load, then:
– Categories AC-1: Ic = Ie
Generally speaking Ic = m x Ie where m is a multiple of the load operational current.
On next pages, the curves corresponding to categorie AC-1 represent the electrical durability variation of standard contactors
in relation to the breaking current Ic.

Electrical durability curves:
– categories AC-1: the curves represent the electrical durability variation of standard contactors in relation to the breaking
5 current Ic.
Electrical durability is expressed in millions of operating cycles.

Curve utilization mode
Electrical durability forecast and contactor selection for categories AC-1
– Note the characteristics of the load to be controlled:
- Operational voltage ............................................. Ue
- Current normally drawn ....................................... Ie (Ue / Ie / kW relation for motors, see "Motor rated operational powers and currents").
- Utilization category .............................................. AC-1
- Breaking current ................................................. Ic = Ie for AC-1
– Define the number of operating cycles N required.
– On the diagram corresponding to the operational category, select the contactor with the curve immediately above the inter-
section point (Ic ; N).

Case of uninterrupted duty
For uninterrupted duty, some verifications of preventing maintenance are necessary to check the functionality of the concerned
product (consult us).
The combined effect of environmental conditions and the proper temperature of the product may require some disposals. As a
matter of fact, for this duty, the use duration prevails over the number of operating cycles.

1SBC100064S0201 - Rev. A

5/232 | ABB