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#193952 - 05/01/10 01:03 AM Wye Delta Start Closed Transition  
DYNAMITE  Offline
Member
Joined: Dec 2003
Posts: 36
Winkler, MB, Canada
Would anyone know how to size the resistors on a Wye start/delta run closed transition starter? Say for a 50 Hp 230V motor?


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#194021 - 05/05/10 04:48 AM Re: Wye Delta Start Closed Transition [Re: DYNAMITE]  
Scott35  Offline

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Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
I believe the Resistors would be sized ("size" = Resistance value - in Ohms), so as to allow the same level of Current that the "Wye" configuration does.

Example:
Motor's FLA = 130 Amps
Starting (Wye Connection) Ampere = +/- 75 Amps
Resistors are sized to allow +/- 75 Amps at rated Voltage.

I am not 100% sure on this, so let me find some references, then reply back.

Scott


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#194026 - 05/05/10 11:54 AM Re: Wye Delta Start Closed Transition [Re: Scott35]  
DYNAMITE  Offline
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Joined: Dec 2003
Posts: 36
Winkler, MB, Canada
That makes sense to me. The smaller you make them the closer to normal current you have. The next question is Watt ratings. The resistors are only in the circuit for a split second in the transition between wye and delta so would you need full power ratings(Peak I^2 R) on them?



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