Re: Running a 20 HP Compressor with phase converter.
- From: Ignoramus12193 <ignoramus12193@xxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 02 Apr 2009 07:03:46 -0500
On 2009-04-02, William <wac@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
"Ignoramus8285" <ignoramus8285@xxxxxxxxxxxxxxxxxxx> wrote in message
news:ZYSdnbqsG8JFVk_UnZ2dnUVZ_vednZ2d@xxxxxxxxxxxxxxx
I had a hard time with something and I do not fully understand why it
did not work.
The story was that I was trying to test a 20 HP compressor that is in
my truck.
My phase converter has two idlers with the total horsepower of 17.5.
I plugged in this compressor into a running phase converter, using
approximately 25 feet of 12 gauge cable.
The motor would spin with difficulty, at about 60 RPM. (one rev per
second).
Then I tried two things.
1) I applied compressed air from my home compressor, to the unloaders
of this compressor.
2) I ran my own compressor, and disabled its unloaders, so that my
compressor would run unloaded. My hope was that after subtracting 2 or
so HP needed to run the compressor unloaded, I would still add perhaps
8 HP to my phase converter, bumping the total HP to 35 or so HP.
Despite doing both of the above things, I could not spin up the 20 HP
Quincy beying 1-2 revolutions per second.
Well here is a bench mark for you... My 390 is running a 20 hp motor, to
start it, with
no air in the tank, it pulls about 140 amps per leg on startup @ almost 500v
( my service is a tad hot and runs 496-500V per leg all the time). So lets
say an easy 280 amps
for just the voltage conversion and more for 3 phase to single phase too. I
bet your whole
house is fed with LESS than a 20 KVA transformer!
I recall that the 10 HP motor in my phase converter spikes at 120 amps
startup. So, your 280 number is pretty much on the spot.
Might want to check the amp draw while your trying to start it up
and see what your getting. If you can't produce that kind of
amperage it will never get it spinning to speed. That of course
assumes that there is nothing wrong with the motor or the pump.....
BTW with the 35 hp VFD running it, I can start and run it on a 20 amp
breaker, VS 65 amps with out.
Betcha it saves you a lot on the utility bill.
How do you like your 390?
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- References:
- Running a 20 HP Compressor with phase converter.
- From: Ignoramus8285
- Re: Running a 20 HP Compressor with phase converter.
- From: William
- Running a 20 HP Compressor with phase converter.
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