question archive A 200 Kw, 220 V, 3-phase, 6-pole, 60 Hz star-delta connected induction motor is running at full load with a armature current of 8 A and an input power of 660 watts
A 200 Kw, 220 V, 3-phase, 6-pole, 60 Hz star-delta connected induction motor is running at full load with a armature current of 8 A and an input power of 660 watts
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A 200 Kw, 220 V, 3-phase, 6-pole, 60 Hz star-delta connected induction motor is running at full load with a armature current of 8 A and an input power of 660 watts. At full load, the line current is 54 A. The mechanical losses is one third of the no-load losses. (a)Compute the stator current rotor speed, output torque and efficiency when the machine is operated at rated voltage and frequency at a slip of 9%?(b) Find the maximum internal torque develop under the following conditions:- 220 V/ 60 Hz?(c) Design the equivalent circuit of a polyphase induction motor? (d) Stator resistance and rotational losses are neglected, Determine the slip and the rotor speed at full load torque? (e) Determine the starting torque at rated voltage and frequency? (f) If the rotor resistance is now trembled by inserting the external resistance in the rotor circuit, For the same full load torque, find the rotor I2R loss at full load torque and developed power at full-load torque and efficiency? (g) In order to get a full load slip of 5%, calculate the percentage reduction in rotor circuit resistance.(include the armature and stator impedance)?
A 3- phase, 6 pole, 1000 r.p.m alternator has an air-gap diameter of 42 cm and a core length of 31 cm. A two layer narrow spread(?δ? =?72??) winding is employed and the winding is accommodated in 4 slots per pole per phase, with 12 conductors per slot. If the per phase reactance of the alternator at 50 Hz is 10 ?Ω?, calculate the circulating current when the machine is delta connected. Determine the phase and line e.m.f in case the narrow-spread coils are connected to form (a) 2-phase winding and (b) 3- phase star-delta connected winding? Also calculate the percentage increase in per phase r.m.s emf due to harmonic. Also, calculate the ratio of resultant line emf to the resultant phase emf. Draw one complete cycle of the emf generated in a single-turn coil-span of 180 degrees electrical. Determine the rms value of the voltage in the single turn coil? Finally calculate the rms value of the fundamental emf per phase?
A squirrel cage induction machine having an rated slip of x% of load having the starting torque different from the full load torque. The induction machine is operating at lowest value of power factor. A separately excited star connected induction machine of 3-phase, 3 pole, 120V, 50Hz impedances r1 = 1.0, r2 = 0.5, x1=x2= 1.2, all the values are in per unit.
When the stator current got constant, the armature current and starting torque will reduced to?. The supply voltage to supply frequency (V/f) is constant, find the constant speed at 38Hz? Also determine the speed of the cascde set? Also determine the braking torque? The effective rotor resistance in the backward branch of the equivalent circuit will be?
