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Entry type: FAQ, Entry ID: 48934955, Entry date: 03/09/2011

3RV20/3RV21 Circuit Breaker: Differences between Circuit Breaker for Motor Protection?

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What differences are between Circuit Breaker for Motor Protection3RV20 and 3RV21?




The differences between the Circuit Breaker for Motor Protection 3RV20 and 3RV21 are as follow:
At overload tripping:
- Circuit Breakers 3RV20 change into the tripped position and the main contacts open. For Reset must the switch knob first manually turn into the Off-Position and accordingly back into the On-Position.
- The main contacts of the Circuit Breakers 3RV21 stay in contrast in close position, the switch knob stay in ON-Position, the lateral alarm contact 96/96 open and the lateral alarm contact 97/98 close (like e. g.  at an overload relay 3RU21). With the contact 95/96 a downstream contactor switch off (necessarily required). After the cooling down of the 3RV21 Circuit Breaker changeover the contact 95/96 automatically back to the closed state, hereby the contactor can electrically switch on. The alarm contact 97/98 switch into open state.
Advantage of the version 3RV21 is that, e. g. in the night shift no electrician engineer is needful to open the control cabinet and reset manually the 3RV21. The restart accrues after cooling down of the Circuit Breaker through the operator on the machine.
At short circuit tripping:
The main contacts of the Circuit Breaker 3RV20 and 3RV21 open and the switch knob change into the tripped position.



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