A large 3 phase 4000 v 60 hz squirrel cage induction motor...

A large 3-phase, 400 V, 60 Hz squirrel-cage induction motor draws a current of 385 A and a total active power of 2344 kW when operating at full-load. The corresponding speed is accurately measured to be 709.2 rpm. The stator is connected in wye and the resistance between two stator terminals is 0.10 Î©. The total iron losses are 23.4 kW and the windage and friction losses are 12 kW. Calculate the active power supplied to the rotor. (3 marks) Choose an appropriate motor's slip and compute the total copper losses in the rotor. (3 marks) Based on the chosen motor's slip in Q4(b)(ii), determine the total mechanical power, output torque, and efficiency of the motor if the rotor speed is 705.6 rpm. (4 marks)

Transcript

00:01 Hello students, this question is related to motor.

00:02 These are the given credentials.

00:03 In the first part of the question, we are asked to find out the active power.

00:06 For that, total input power is equal to total active power plus total loss, which is equal to 2344 plus 23 .4 plus the friction loss 12 kilowatt.

00:31 Total input power is equal to 2379 .4 kilowatt.

00:41 Further, the total input power is equal to active power of stator plus active power of rotor.

01:01 We are asked to find out the active power of the rotor, power of rotor, which is equal to total power, that is 2379 .4 minus 2344 .0 implies the active power of rotor is equal to 35 .4 kilowatt.

01:31 Further, in the next part of the question, we are asked to find out the slip, that is, s slip is equal to 120 into frequency divided by number of poles implies s is equal to 120 into 60 divided by 2, which is equal to 3600 rpm, that is, s is equal to 3600 rpm implies, sorry, this is equation for synchronous speed, s is equal to, that is, slip s is equal to n s minus n divided by n.

02:09 Substituting the values, 3600 minus 709 .2 divided by 3600, slip is equal to 0 .802.

02:21 This is equation and this is the result for slip is equal to 0 .802.

02:25 Further, in this question, we are asked to find out rotor copper loss.

02:29 The equation is rotor copper loss is equal to 3 into rotor current into r, that is, rotor copper loss is equal to, copper loss is equal to 3 into rotor current is 148225, the whole square, that is, the value, current i is equal to 385 and its square is equal to this into r, r is equal to 0 .1 and the copper loss, rotor copper loss is equal to 444670650 watt, which is equal to rotor copper loss is equal to 4 .45 kilowatts.

03:14 Further, in the next part of the question, we are asked to find out total mechanical power...

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