A3-1 Motor Power

Motors are used to convert electrical energy into mechanical energy

Note that motors will typically show their power as mechanical power. Not electrical.

Parameters

pm = mechanical or shaft power. This is the power after conversion.

p = electrical input real power.

q = reactive power (var). This is the reactive power consumed by the motor.

s = apparent power.

pf = power factor. Simply the ratio of real power (p) over apparent power (s)

η = efficiency of motor.

v = volts. Either line or phase voltage depending if it is a polyphase system. $v_{\mathrm{line}}=\sqrt{3}·v_{\mathrm{phase}}$ .In Australia this is 415v (400v officially) and 240v (230v officially) respectively.

i = amps. Line current.

Ideally to minimise circuit losses, power factor should be 1. If power factor is less than 1 then more current is needed in the circuit to deliver the same real power thereby requiring larger cables, more voltage drop and more line resistive losses. Note the resistive losses are real power and this why network planners and engineers try to keep power factor as close to 1 as possible.

A typical motor nameplate.