Three phase induction motor soft start,
It depends on the power rating of the motor.
For a few horse power you can fit three high power resistors (one in each phase) and short them out with a contactor on a timed delay.
Or fit an inverter drive or soft start unit.
Something like an Altistart:
http://www.adara-bg.com/techinfo/sch...al%20ATS48.pdf
You could also use a star delta starter..this will reduce the start up torque. However running cost is higher in Delta because you use more current than in Star. The Star Delta starter will not give a graduated start up like a Gradivar unit:
http://www2.schneider-electric.com/r...itation_en.pdf
Remember to put any safety or enable contactors before the drive not between the drive and motor or you will get an output fault.
The design etc is up to the engineer.. so no further comment.
One other thought most units are soft start and soft stop units because if you have problems like broken feet due to inertia then the motor can fail on ramp down so you get a exponential curve of speed which is also good for accurate positioning.
Regards
M. Gregg
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Last edited by M Gregg; 24th January 2013 at 05:15 PM.
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Need 3 phase Squral cauge induction moter soft starter
