The answer to Power Factor
A single phase electric motor has an output power of 10 kW and an efficiency of 90% at full load. The motor is fed from a 240 V supply via a cable that has a resistance of 10 milli ohms per metre length. If the terminal voltage to the motor must not fall below 90% of the supply voltage, calculate the maximum return length of the cable for a motor power factor of:
A. unity
B. 0.8 (sketch a circuit diagram and phasor diagram, the motor and line voltages are no longer in phase)
C. The power dissipated in the cable for each of the above two cases.