A 3-phase, 3-phase 4-pole star-connected squirrel-cage rotor asynchronous motor with 50 Hz, 230 V phase-to-phase drives a mechanical load at 1450 rpm. The Rc iron resistance is 200 Ohm, at which time the iron losses are equal to the copper losses in the rotor. The stator copper losses are 800 W, the sum of the mechanical losses is 200 W. Pcu2(rotor copper losses) and % efficiency are given correctly in which of the following? (desired equivalent circuit can be used.)
A 3-phase, 3-phase 4-pole star-connected squirrel-cage rotor asynchronous motor with 50 Hz, 230 V phase-to-phase drives a
Pcu2(rotor copper losses) and % efficiency are given correctly in which of the following? (desired equivalent circuit can be used.)
I) Pcu2= 88.167 W
II) Pcu2= 264.5 W
III) Pcu2= 793.5 W
IV) Efficiency = 67%
V) Efficiency = 83%
VI) Efficiency = 89.814%
An AC motor is an electrical machine which takes AC electrical input energy and produces mechanical output energy at the shaft. In most of the application AC motors are used.
The major classification of AC motors are:
- Induction motor
- Synchronous motor.
An Induction motor is a machine whose operating principle is based on Faraday's law of electromagnetic induction. The energy is transferred from stator to rotor with the help of electromagnetic induction. It is said that most of the machine used in electrical power system more than 90% is induction motor. Sometimes induction motor is also called asynchronous motor as it rotates other than synchronous speed.
Synchronous motor also known as synchronous condenser is a constant machine which only operates at synchronous speed or else come to standstill, so the name synchronous speed. Synchronous motors are also used to improve the power factor of the system by operating them at no load with over excitation.
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