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Why do some ATS01 control diagrams indicate at least 5seconds between a STOP and the next START?

Published date: 15 January 2019

Issue:
Why do some ATS01 control diagrams indicate at least 5seconds between a STOP and the next START?

Product Line:
ATS01

Environment:
Models ending in ...LU/QN/RT/FT

Cause:
Application may require shorter times.

Resolution:
The 5seconds between STOP and next START are indicated when the STOP type is freewheel, coast to stop.  When a freewheel stop is requested, the motor is de-energized and is demagnetized. The time for demagnetization is exponential and depends on the size, type and voltage of the motor. It is about 5 times the rotor constant. So engineering defines a time value before the next run command because if the motor is supplied before it is completely demagnetized, the voltage applied on the remaining flux is not in phase, and at this moment the current can become huge. Since the ATS01 does not limit the current, a failure could occur on the starter, motor or load.
The ATS01 internal delay time from stop to start is about 250ms. After stop, the next start is possible after 250ms. The instruction diagrams indicate a longer time to next start in order to be sure that the load has reduced the speed and no restart is possible during demagnetization.

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