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Masterpact NW breaker will not close on first attempt but does close on second attempt. Why?

Issue:
Masterpact NW breaker will not close on first attempt but does close on second attempt.  Why? 

Product Line:
Masterpact NW

Cause:
Troubleshooting

Resolution:
The breaker requires a shunt trip energization time of 200 ms to ensure that the breaker trip mechanism has completed its cycle and has returned to its starting point.  A shorter signal has the risk of causing the mechanism to hang up and not close with the next close signal.  It would close with a second signal however.  The same applies to the shunt close signal.  It must be 200 ms or more.
To prevent  such an operating problem, do not pass the signal through an aux. contact (which will open in less than 50 ms), and if a PLC is used, ensure the signal duration is 200 ms or more.  


 
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