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**RESOLVED** Correct motor voltage

Posted: Sun Aug 08, 2010 6:59 pm
by Captain Midnight
My transformer has three taps available. 110, 117, 129, volts DC. Which should I chose for a 141 volt motor?
Thanks

Re: Corect motor voltage

Posted: Sun Aug 08, 2010 11:45 pm
by cncsnw
Transformers do not output DC power.

It is conceivable that your transformer, if it was built for the dedicated purpose of feeding a DC rectifier assembly, could have labels that represent the expected DC voltage after you rectify the AC coming from that set of secondary taps. If that is the case, then you could use any of the three. Lower voltage will be easier on your drive and motors in the long run; higher voltage will allow faster rapid speeds.

If, like most transformers, your tap labels represent the AC output, then even the lowest (110VAC) will be too high (probably giving you a little over 150VDC out of your rectifier).

That assumes, of course, that you are putting in the full primary voltage. If the transformer primary is marked 240VAC and you feed it with 208VAC, then your secondary voltages will likewise be 86% of nominal. In that case you would get 95VAC out of the 110VAC secondary, and would get about 134VDC from the rectifier.

What is your primary (line) voltage?

What is the primary voltage marked on the transformer?

Do the transformer secondary taps really say "volts DC", or do they just have numbers?

Re: Corect motor voltage

Posted: Mon Aug 09, 2010 1:59 am
by Captain Midnight
My transformer has three taps available, and after rectifing them to DC, I have thee choices to use. 110, 117, 129, volts DC. Which should I chose for a 141 volt motor?
Thanks

Re: Corect motor voltage

Posted: Mon Aug 09, 2010 10:12 am
by Centroid_Tech
Captain Midnight,

The ideal DC voltage would be the 117VDC.

Re: Corect motor voltage

Posted: Mon Aug 09, 2010 3:06 pm
by Captain Midnight
Thank you for your help.