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ECE_320_Homework7

# ECE_320_Homework7 - 2 The developed power P dev 3 The...

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ECE 320 Homework # 7 Due March 21 Problem 1 A three-phase induction machine is rated 460V L ° L , 60Hz, 1740 RPM, connected in Y and has the following parameters: R s = 0 : 25° R r = 0 : L ls = L lr = 1 mH L m = 0 : 08 H Find the following: 1. Number of poles 2. Stator current at rated conditions 3. Starting current when started on a full rated voltage 4. Rated torque on the shaft of the machine, neglecting all the losses. Problem 2 A 60 Hz 460V L ° L three-phase squirrel-cage induction motor draws 40 A phase current with a power factor of 0.85 lagging at rated speed. The total stator ohmic (copper) loss is 1 : 5 kW , the total rotor ohmic loss is 1000 W. Find the following quantities: 1. The air-gap power P air ° gap . 2. The developed power P
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Unformatted text preview: 2. The developed power P dev . 3. The output power P out: 4. The motor e¢ ciency. 5. If the motor has a mechanical synchronous speed of 1200 rpm and a rated slip of 3%, &nd the developed torque T dev . Problem 3 A three-phase induction machine is connected in Y and has the following para-meters: R s = 0 : 12& R r = 0 : 2& L ls = L lr = 1 : 12 mH L m = 43 mH Find the following quantities: 1. For the supply voltage of 230V L & L 60Hz &nd starting torque, current and power. 2. Calculate the maximum torque and corresponding speed and e¢ ciency 3. At slip of 2% &nd current, power factor and e¢ ciency. 1...
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• Spring '08
• Jurkovic
• Electric motor, e¢ ciency, following parameters, three-phase induction machine, three-phase squirrel-cage induction

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