Supercomputers, fishing for information

Jon Elson elson at
Tue Nov 8 20:24:06 CST 2016

On 11/08/2016 11:55 AM, Paul Koning wrote:
> The classic formula is 1 hp = 750 W.  But there's more to the picture.  Motors draw a steady state current based on the power demanded from them, and the hp rating shows the max that they are designed for.  But when starting they draw much more current.
Well, actually, motors draw a fairly constant current, and 
the phase angle between current and the applied voltage 
changes with load.  At idle, a motor draws almost pure 
lagging current (phase almost 90 degrees lagging the 
voltage) and at full load the current is nearly in phase 
with the voltage.  So, the POWER draw changes with load, but 
the line current changes much less!


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