A single-phase, 120 V, 60 Hz, four-pole, split-phase induction motor gave the following blocked rotor test data: VIP Main winding 32 4 80 Auxiliary winding 40 4 128 a) Determine the standstill impedances of the main and auxiliary windings. b) Determine the values of the resistances to be added in series with the auxiliary winding to obtain maximum starting torque. c) Compare the starting torques and starting currents with and without the added resistance in the auxiliary winding circuit if the motor is connected to a 120 V, 60 Hz supply

A single-phase, 120 V, 60 Hz, four-pole, split-phase induction motor gave the following blocked rotor test data: VIP Main winding 32 4 80 Auxiliary winding 40 4 128 a) Determine the standstill impedances of the main and auxiliary windings. b) Determine the values of the resistances to be added in series with the auxiliary winding to obtain maximum starting torque. c) Compare the starting torques and starting currents with and without the added resistance in the auxiliary winding circuit if the motor is connected to a 120 V, 60 Hz supply

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter32: Three-phase Motors

Section: Chapter Questions

Problem 6RQ: Name three factors that determine the torque produced by an induction motor.

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A 3 – phase induction motor has a 4 – pole, star – connected stator winding. The motorruns on a 50 – Hz supply with 200 V between lines. The rotor resistance and standstillreactance power phase are 0.1 and 0.9 ohm respectively. The ratio of rotor to stator turnsis 0.67. Calculate (a) total torque at 4 % slip, (b) total mechanical power at 4 % slip, (c)maximum torque, (d) speed at maximum torque, (e) maximum m power
A four-pole, single-phase, 120 V, 60 Hz induction motor gave the following standstill impedances when tested at rated frequency:Main winding : Zm =1.5+j4 ohmsAuxiliary winding : Za =3+j6 ohmsa) Determine the value of external resistance to be inserted in series with the auxiliary winding to obtain maximum starting torque as a resistor split-phase motor.b) Determine the value of the capacitor to be inserted in series with the auxiliary winding to obtain maximum starting torque as a capacitor-start motor.c) Determine the value of the capacitor to be inserted in series with the auxiliary winding to obtain maximum starting torque per ampere of the starting current as a capacitor-start motor.d) Compare the starting torques and starting currents in parts (a), (b), and (c) expressed as per unit of the starting torque without any external element in the auxiliary circuit, when operated at 120V, 60Hz.
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18. A single-phase, 120 V, 60 Hz, four-pole, split-phase induction motor has the following standstill impedances:Main winding: Zm =5+j6.25Auxiliary winding: Za =8+j6a) Determine the value of capacitance to be added in series with the auxiliary winding to obtain maximum starting torque.b) Compare the starting torques and starting current with and without the added capacitance in the auxiliary winding circuit when operated from a 120V, 60Hz supply.
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Torque-speed characteristics for three phase induction motor 4. Discuss the following (rated torque, starting torque, break down torque).
1.why the slip of induction motor is never zero, 2.what happens if the slip of induction motor is one, 3.what is the value of the slip for an induction motor at on load and full load
a) Why the slip of induction motor is never zero, b) What happens if the slip of induction motor is one, c)What is the value of the slip for an induction motor at no load and full load.
An 3-phase induction motor(IM) has full load slip = 0.5%. If the rotor circuit resistance is increased so that R2new =2R2old, then the slip at which the motor develops the same full load torque is=.. * ......
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