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Entry type: FAQ Entry ID: 21502783, Entry date: 01/16/2018
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Using coupling relays for switching large power contactors together with 3RN1 / 3RN2 thermistor motor protection device

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This FAQ content statements for switching large power contactors together with 3RN1 / 3RN2 thermistor motor and coupling relays inside and outside of hazardous areas.

QUESTION:

Switching large power motors in hazardous areas:
For controlling the magnet coils of powerful contactors, can coupling relays be put in between the switching contacts of the 3RN1 / 3RN2 thermistor motor protection device or does the 95/96 contact of the thermistor motor protection device have to be switched directly into the control circuit of the contactor?

 

 

ANSWER:

As regards controlling power contactors with 3RN1 /3RN2 thermistor motor protection devices, the following statement is valid:
If the power consumption of the contactor coil to be controlled exceeds the ON and OFF switching capacity of the relay contacts of the 3RN1 / 3RN2 thermistor motor protection device, then an additional contactor or relay with sufficient switching capacity can be used as an interface for strengthening the contacts. This is also valid for applications for motor protection in hazardous areas.




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