Question 2 [10 marks) A six pole, three phase induction motor, with a star connected stator...
5 Marks) A 4-pole, 3 phase, 50 Hz, 230 V induction motor. Each phase of rotor winding b) has one-fourth the number of turns of each stator. The full-load speed is 1,455 rpm. The rotor resistance is 0.3 Ω and rotor standstill reactance is 1.0 Ω per phase. The rotor and stator windings are similar. Stator losses are equal to 50 Watts. Friction and windage losses are equal to 30 W. Calculate ) Blocked rotor voltage per phase. 2 Marks)...
The parameters of a 400V, 50Hz, three phase star connected induction motor are: Stator impedance ?1 = 1.7 + ?4 ohm/phase Referred rotor impedance ?2 ′ = 1.2 + ?2.6 ohm/phase Magnetizing impedance ?0 = 5 + ?60 ohm/phase Determine the torque at a slip of 5% using : a) The exact equivalent circuit b) The approximate equivalent circuit
Question 11: (3 marks) A 6 pole, 60 Hz, star connected three-phase induction motor has a rating of Pm = 55 kW and line voltage = 420 V. The slip of the motor is 2% at 0.9 power factor lagging. If the full load efficiency is 95%, calculate the torque developed in the motor.
Consider a 50 kW, 3-phase, 380 V line-to-line, 50 Hz, 6 pole Y-connected wound-rotor induction motor. The stator winding ac resistance is 0.1 Ω/phase. The effective stator-to-rotor turns ratio is 2. The exciting branch is negligible. It is found that when an external resistor of 0.09 Ω/phase is connected to the rotor terminals maximum starting torque of 1150 Nm is obtained. a. Compute the internal mechanical power and the internal torque developed by this motor when it drives a load...
Q3. A single-phase, 120 V, 60 Hz, four-pole, split-phase induction motor has the following equivalent circuit parameters: Stator parameters: The Main winding (R =1.512, X=2.522), and the auxiliary winding (R=2.512, X=2.52), Rotor parameters referred to the stator side: (R=1N, X=1.592). The magnetizing reactance is equal to 4082. (a)Determine the standstill impedances of both windings. (b)Determine the starting torque and the starting current of the motor if it is started from rated voltage mains as a split phase induction motor. (c)Determine...
4.6. A 460-V, 75 kW, 4-pole, delta-connected, 60-Hz, three- phase induction motor has a full-load slip of 5 percent, an efficiency of 92 percent and a power-factor of 0.87 lagging at full-load. At start-up, the motor develops 1.9 times the full load developed torque but draws 7.5 times the rated current at the rated voltage. This motor is to be started with an auto- transformer reduced-voltage starter. Assume the stator resistance and the stator core loss to be negligible. Calculate...
-23 An 8-pole, 230-V, 60-Hz, A-connected, three-phase induction motor has a rotor impedance of 0.025 + 0.112/phase. The stator winding impedance is negligible. Determine (a) the speed at which the motor develops the maximum torque, (b) the maximum torque of the motor, and (c) the start- ing torque as a percentage of maximum torque. What additional resistance must be inserted in the rotor circuit to make the starting torque equal to 75% of the maximum torque?
Problem Solving: 1. A 220V, 4-pole, 60Hz, 1-phase induction motor has an effective rotor resistance and leakage reactance of 0.5 Ohms and 5 ohms respectively. It is running at a speed of 1,800 rpm. Determine: a. Frequencies of forward and backward rotor current components b. Relative magnitudes of forward and backward fluxes. Neglect magnetizing current and stator impedance. A 220-W, 2-pole, 115-V, 60-Hz single-phase induction motor delivers rated output at a slip 10%. The total copper loss at full load...
Question: The equivalent circuit of a 440 V, 3-phase, 8 pole, and 50 Hz star-connected induction motor is shown in figure 1. The short-circuit test is conducted with a locked rotor and a line current of 80 A. The open-circuit test is conducted by supplying the stator winding at rated voltage and at the rotor is rotating freely without any mechanical load. Fig. 1 The per-phase equivalent circuit of a 3-phase induction motora) Determine the line voltage and power factor on the...
The equivalent circuit of a 440 V, 3-phase, 8 pole, and 50 Hz star-connected induction motor is shown in figure 1. The short-circuit test is conducted with a locked rotor and a line current of 80 A. The open-circuit test is conducted by supplying the stator winding at rated voltage and at the rotor is rotating freely without any mechanical load.a) Determine the line voltage and power factor on the short circuit test;b) We need to apply a low...