.37kw vfd for a .75kw motor
.37kw vfd for a .75kw motor
(OP)
Guys,
In my searches, I have not found any information regarding the underspec of a VFD. I already have some 0.75kw motors on small conveyors (from another job), and need to purchase some VFD's for them. However, I do not need their full rated power. In fact, they are for conveying tree nuts, and could probably be a 1/10 hp motor on each conveyor.
Will I have problems using .37kw drives on these .75kw motors? Will the drives current protect themselves? (obviously they will be running a load below their power capacity) For reference, I am looking at WEG 240V single phase to 3 ph drive. (CFW10 240V EASYDRIVE IP20)
Thanks in advance,
Michael
In my searches, I have not found any information regarding the underspec of a VFD. I already have some 0.75kw motors on small conveyors (from another job), and need to purchase some VFD's for them. However, I do not need their full rated power. In fact, they are for conveying tree nuts, and could probably be a 1/10 hp motor on each conveyor.
Will I have problems using .37kw drives on these .75kw motors? Will the drives current protect themselves? (obviously they will be running a load below their power capacity) For reference, I am looking at WEG 240V single phase to 3 ph drive. (CFW10 240V EASYDRIVE IP20)
Thanks in advance,
Michael





RE: .37kw vfd for a .75kw motor
Why doing this? Is there an economic advantage?
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: .37kw vfd for a .75kw motor
Thanks for the response. There is quite an economic advantage, as a supplier has some surplus .37's which are about 1/2 price of the .75's. Is there an easy way to determine what excitation current would be drawn by my motors?
As for reduced voltage, I am think this VFD will be operating in constant V/f mode - and so operating at say 25hz (for Australia) would be half voltage.
If this is correct, then I *should* be fine?
Michael
RE: .37kw vfd for a .75kw motor
Buy one of the .37 inverters. Connect and test run. There is usually (always) a parameter that sets motor voltage at nominal frequency. Adjust that so that your magnetizing current (proportional to voltage, more or less) when idling at full speed doesn't overload the inverter.
Also. If the motor can be wye/delta connected and delta is for your voltage. Then the wye connection reduces magnetizing current. The motor gets weaker in both cases, but since the shaft load is low, it will probably work out well.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: .37kw vfd for a .75kw motor
What I have learned so far:
*For a motor that is 'idling', then magnetizing current should be my limiting factor.
*I can get around this by decreasing voltage at 'X' frequency, or connecting in wye (it is currently delta)
So, on this information, I will get the smaller units at substantial savings...
Thanks for the tips.
Michael
RE: .37kw vfd for a .75kw motor
Keith Cress
kcress - http://www.flaminsystems.com
RE: .37kw vfd for a .75kw motor
Just for curiosity, can you find better value? I might have to share that beer if so...
cheers
RE: .37kw vfd for a .75kw motor
Hmm.. Sorry, came to think about Keith's idea of not drinking beer.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: .37kw vfd for a .75kw motor
Risingtenpi; Here's an example: (Note the 230V single to 3ph)
htt
Keith Cress
kcress - http://www.flaminsystems.com
RE: .37kw vfd for a .75kw motor
LPS for you and friend Gunnar.
Bill
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"Why not the best?"
Jimmy Carter
RE: .37kw vfd for a .75kw motor
RE: .37kw vfd for a .75kw motor
Check the motor starter prices.
Keith Cress
kcress - http://www.flaminsystems.com
RE: .37kw vfd for a .75kw motor
Looks like I'm Buying!
I too like that site. Shipping is a bit expensive to Australia, but I am heading over that way in 2 weeks - I can wait that long to save US$150 for shipping!!!