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Re: The chilling truth about cold horsepower
- To: aquatic-plants at actwin_com
- Subject: Re: The chilling truth about cold horsepower
- From: Bill Wichers <billw at waveform_net>
- Date: Wed, 11 Jun 2003 10:31:06 -0400
I also began thinking about the total electrical power a 1 HP motor draws.
Bill is right when he listed many types of motors. I was just going to
choose one and see what the locked rotor or full load amps rating is. That
will give the total energy going into the motor. As Bill said that energy
is partially converted to heat and lost( the label on the motor will list
the Temperature rise). Most (we hope) is converted to rotational energy. I
think that even the sound it produces as it runs is a source of energy
loss even though it is probably an extremely small amount. Can you think
of any others?
Locked rotor current is a WORST CASE and is significantly more than the
motor's running current which is a better measure of the energy going into
the motor. Locked rotor current is usually used to determine circuit sizing
and overcurrent device trip ratings.
Motor losses are mostly thermal, which are both from electrical (resistive)
losses and frictional losses in bearings. Sounds too would be a loss, but I
doubt that would be even a single watt worth of loss and I wouldn't worry
about it for our purposes. ANYTHING that isn't making the shaft twirl
around is a loss in a motor, since ideally ALL the input energy will come
out as rotational energy in the shaft.
UNIX Systems Administrator