A 220V 50Hz capacitor - start induction motor has the impedances for the main and auxiliary windings with 3 + j7 and 11+ j3 respectively at starting. Calculate the value of capacitance to be connected in the auxiliary winding circuit so that the main and auxiliary winding currents are in quadrature at starting.

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A value of magnetizing current in a 3-phase induction motor * gives power factor smaller .. larger smaller. .poor large . better O large...poor O

A three-phase, 3.3 kV, 50 Hz power supply is used to drive an induction motor. The motor has an eight-pole, star-connected stator. The rotor is also star-connected, with the line ends brought out to sliprings for starting and speed control. At standstill, the open circuit voltage induced on the rotor, as measured between the sliprings, is 1475 V. At the full load speed, the frequency of the induced emf on the rotor winding is 2.5 Hz. The motor has the following parameters: Rc = 250 Q R₁ = 0.1Q Xm=250 X₁ = 0.35 Q R2 = 0.04X2 = 0.30 By referring the rotor quantities to the stator, calculate the following: (i) The shaft output power and torque of the fully loaded motor, if the corresponding friction and windage losses are 44 kW;

Q5)A- A 3-phase Induction motor has an efficiency of 0.91 when it delivers an Output power of 22KW. At this load,the stator copper losses equals the rotor copper losses and the total copper losses equals the no- load losses the mechanical losses are one-fourth the no-load losses Find the slip write equations with drawing power flow Diagram ? B-Define the following: (i)Regulation (ii) Slip (iii)Core and shell Transformer (iv)PM motor

A 3-0, 50-Hz induction motor with its rotor star-connected gives 500 V (r.m.s.) at standstill between slip-rings on open circuit. Calculate the current and power factor in each phase of the rotor windings at standstill when joined to a star-connected circuit, each limb of which has a resistance of 10 Q and an inductance of 0.03 H. The resistance per phase of the rotor windings is 0.2 Q and inductance 0.03 H. Calculate also the current and power factor in each rotor phase when the rings are short- circuited and the motor is running with a slip of 4 per cent. [13.6 A, 0.48; 27.0 A, 0.47] (London University) A 4-pole, 50-Hz, 3-phase induction motor has a slip-ring rotor with a resistance and standstill reactance of 0.04 2 and 0.2 2 per phase respectively. Find the amount of resistance to be inserted in each rotor phase to obtain full-load torque at starting. What will be the approximate power factor in the rotor at this instant ? The slip at full-load is 3 per cent. [0.084 2, 0.516 p.f.]…

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6- Which of the following supply is given to the rotor winding of 3-Phase Induction Motor: a) DC Supply b) AC Supply c) No Supply d) Pulsating Supply 7- 3-Phase Induction Motor will have Starting Torque and Starting Current a) High, High b) Low, Low. c) High, Low d) Low, High 8- Which of the following method is used for controlling the speed of an induction motor: a) Changing number of stator poles b) Supply voltage control c) Frequency control d) All the options are correct 9- Which of the following method cannot be used for starting of 3-Phase Squirrel Induction Motor: a) Star-Delta Starting b) Line resistor startling c) transformer Starter d) Rotor Resistance Starting 10- The rotor of a stepper motor has no: a) windings b) commutator c) brushes d) all of the above

3-Phase 50Hz 6 pole induction motor has rotor resistance of 0.1 ohm and reactance of 0.92. ignore voltage drop in stator and assume thee rotor resistance is constant. Full load slip is 3%, then find Tmax /Tfl

The resistance and reactance per phase of the rotor of a 3-phase induction motor are 0.6 ohm and 5 ohms respectively. The induction motor has a star-connected rotor and when the stator is connected to a supply of normal voltage, the induced e.m.f. between the slip rings at standstill is 80 V. Calculate the current in each phase and the power factor at starting when (i) the slip-rings are shorted, (ii) slip-rings are connected to a star-connected resistance of 4 ohm per phase.