When the motor overload protection is set, it is based upon the specific
motor's full load current. This must be set as close to the actual
motor's nameplate rating and changed if the motor is replaced with
another of different specs. Since a highly efficient motor will draw
less current at maximum mechanical load, the overload protection must be
set to this lower level or it may be damaged in the event of a
mechanical overload.
One Horsepower = 746 watts
Technically Speaking, this usually refers to the actual power
consumption or true power. Electric Meters (like the kind your
utility provides for your house) will always read true power. A fancy
commercial meter might read more parameters.
The VA rating (Volts x Amps) will always be higher for a motor
depending on the p.f. (powre factor). This is also called apparent
power since it reflects a higher current flow that is used to
establish the magnetic fields within the motor. During each
sinusoidal AC cycle, extra power is extracted from the source and
then returned to the circuit as the field alternately expands and
contracts.
pf = 100 x (True Power WATTS/ Apparant power (VA))
A perfect resisitance load will have power factor of 100%.
A motor or any load with coils will always have a power factor of less
than 100%. With small scale residential loads, the utilities usually
don't care, but in a commerical or industrial billing situation, you
usually have to pay a penalty for having a low power factor.
Beachcomber