Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!rutgers!tut.cis.ohio-state.edu!ucbvax!hplabs!hp-pcd!hplsla!tomb
From: tomb@hplsla.HP.COM (Tom Bruhns)
Newsgroups: sci.electronics
Subject: Re: 220 vs. 110 motor efficiency
Message-ID: <5170025@hplsla.HP.COM>
Date: 5 Apr 89 22:56:56 GMT
References: <3272@ihlpm.ATT.COM>
Organization: HP Lake Stevens, WA
Lines: 40

>In article <3272@ihlpm.ATT.COM> wrv@ihlpm.ATT.COM (Vogel) writes:
>>Over the weekend I had a conversation with the local pool supply
>>company service person.  We got on the subject of pumps, and he asked
>>me if my pump was ok, and how it was connected.  I told him it was connected
>>to 110V (by previous owner), but it could also run at 220.  He said I
>>should convert it, that this would give a great savings in the power bill.
                                            ^^^^^^^^^^^^^
I doubt it...

>>So somebody please tell me, is the pool guy whacko, or am I missing
>>something?
>>	-Bill [waiting for summer so I can swim......] Vogel, ihlpm!wrv
>He is probably right.  The current will be lower for the same amount
 ^^^^^^^^^^^^^^^^^^^^
Again, I doubt it...   You will have about 1/4 the I^2*R loss in the
wire leading to the motor if you run it at 240 instead of 120.  But
I'd be surprised if you have more than .3 ohms (about 100 feet of
2-conductor 12 gauge), and that means around 100 watts max.  Maybe
1/2 cent per hour?  It adds up, but a "great savings"??  And rewiring
the motor for a higher voltage most likely will put two windings in
series that used to be in parallel, for the same net I^2*R loss in
the motor.  I submit that the most noticable change will be faster
starting of the motor; it may draw a rather large starting current
and the lower drop in the line would be noticable at that time.

>of power at the higher voltage.  This means that you will have less 
>loss due to the resistance of the wire.  This is why power it usually 
>transamitted at high voltage/low current.  If your wire length is long,
>you probably would have some savings both in the wire, and the internal 
>wiring of the motor.  It the run is short, it won't make much difference.
>Generally, it is best to run motors and other appliances at the highest
>voltage available.
>
>JRV
>
>Jon R. Vermilye                          		         315 341 2138
>Department of Theatre                              vermilye@oswego.Oswego.EDU
>SUNY Oswego                                   rutgers!sunybcs!oswego!vermilye
>Oswego, NY 13126
>----------