A 30 HP motor is running a 15 HP pump. What is the load factor of the motor? The

Question

A 30 HP motor is running a 15 HP pump. What is the load factor of the motor? The motor in Problem 2 is a three phase, 460 volt motor, that draws 37 amps at full load. What is the full load power factor of the motor? A 40 HP AC induction motor has a full load speed of 1760 RPM. The actual running speed was measured in a manufacturing laboratory at 1773 RPM. The manufacturing lab tells us that the motor load factor would be the ratio of the (no load speed minus the actual running speed) divided by the (no load speed minus the full load speed). What is the load factor of the motor? A 100 nameplate HP motor AC induction motor has a load factor of 70%, and an efficiency of 92.3%. What is the kW input to the motor? A three phase 460 volt AC induction motor draws a current of 80 amperes, and has a power factor of 85%. What is the kW input to the motor? An AC induction motor draws 100 kW and has a power factor of 75%. How many kVAR of capacitance should we put on the motor

Explanation / Answer

73) load factor = Average demand / maximum demand = 15/30 = 0.5

76) input kw = (0.7457*hp*load)/efficiency = (0.7457*100*70)/92.3 = 56.55 kw

77) root 3 * voltage * current * power factor = 1.732* 460*80*0.85 = 54,176.96 Watts

78)

Motor input = P = 100 kW

Original P.F = Cos1 = 0.75

Final P.F = Cos2 = 0.90

1 = Cos-1 = (0.75) = 41°.41; Tan 1 = Tan (41°.41) = 0.8819

2 = Cos-1 = (0.90) = 25°.84; Tan 2 = Tan (25°.50) = 0.4843

Required Capacitor kVAR to improve P.F from 0.75 to 0.90

Required Capacitor kVAR = P (Tan 1 – Tan 2)

= 100kW (0.8819 – 0.4843)

= 39.76 kVAR

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