Q1: A single-phase induction motor is rotating at a speed of 1790 rpm. Itsrated nameplate is; 150-V, 60-Hz, 4-pole. Determine its per-unit slip (a) in thedirection of rotation and (b) in the opposite direction. At standstill the rotorresistance is 13 2, determine the effective rotor resistance in each branch.Q2: A single-phase induction motor with a 4-pole, 50-Hz, 130-V, is rotatingin the clockwise direction at a speed of 1450 rpm. Determine its per-unit slip(a) in the direction of rotation and (b) in the opposite direction. At standstillthe rotor resistance is 15 2, determine the effective rotor resistance in eachbranch.

In this question, single phase induction motor is given..We have to find its slip in forward…

single-phase induction motor is rotating at a speed of 1790 rpm. It ameplate is; 150-V, 60-Hz, 4-pole. Determine its per-unit slip (a) in th on of rotation and (b) in the opposite direction. At standstill the roto nce is 13 2, determine the effective rotor resistance in each branch. single-phase induction motor with a 4-pole, 50-Hz, 130-V, is rotatin, clockwise direction at a speed of 1450 rpm. Determine its per-unit sli he direction of rotation and (b) in the opposite direction. At standstil or resistance is 15 2, determine the effective rotor resistance in eac

single-phase induction motor is rotating at a speed of 1790 rpm. It ameplate is; 150-V, 60-Hz, 4-pole. Determine its per-unit slip (a) in th on of rotation and (b) in the opposite direction. At standstill the roto nce is 13 2, determine the effective rotor resistance in each branch. single-phase induction motor with a 4-pole, 50-Hz, 130-V, is rotatin, clockwise direction at a speed of 1450 rpm. Determine its per-unit sli he direction of rotation and (b) in the opposite direction. At standstil or resistance is 15 2, determine the effective rotor resistance in eac

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter35: Harmonics 916

Section: Chapter Questions

Problem 3RQ: Would a positive-rotating harmonic or a negative-rotating harmonic be more harmful to an induction...

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Name three factors that determine the torque produced by an induction motor.
A three-phase induction motor, operating at rated voltage and frequency, has a startingtorque of 1.35 times and a maximum torque of 2.2 times, both with respect to its rated-loadtorque. Ignoring the effects of the stator resistance and rotational losses and assumingconstant rotor resistance, determine the slip rated load, and the rotor current at starting (as a percentage of the rotor current at rated load). The slip at maximum torque is 0.343 if that helps.
a. A three-phase, 220-V, 60-Hz induction motor runsat 1,140 r/min. Determine the number of poles (forminimum slip), the slip, and the frequency of therotor currents.b. To reduce the starting current, a three-phasesquirrel cage induction motor is started byreducing the line voltage to Vs/2. By what factorare the starting torque and the starting currentreduced?
A three-phase induction motor, at rated voltageand frequency, has a starting torque of 140 percentand a maximum torque of 210 percent of full-loadtorque. Neglect stator resistance and rotational lossesand assume constant rotor resistance. Determinea. The slip at full load.b. The slip at maximum torque.c. The rotor current at starting as a percentage offull-load rotor current.
A three-phase induction motor, operating at rated voltage and frequency, has a startingtorque of 1.35 times and a maximum torque of 2.2 times, both with respect to its rated-loadtorque. Ignoring the effects of the stator resistance and rotational losses and assumingconstant rotor resistance, determine the slip at the maximum torque;
A 6-pole, 50 Hz, 3-phase induction motor runs at 960 rpm while delivering a shaft torque of 120 N-m. If friction and windage loss amount to 180 W., determine the rotor copper loss.
The full load slip of a 4-pole, 60Hz, 440V (line-to-line) three phase induction motor is 0.05. (i). What is the speed of the rotating stating? What is the frequency (in Hz) of the rotor current? (ii). When the output power of the motor is 90 hp at a speed of 1732 rmp, rotational losses (which include frictional and core losses) are 10,100W, while copper losses for both the rotor and stator total 3700W. Determine the motor efficiency and line current, assuming the motor has a 0.8pf lagging under the conditions.
The rotor resistance and reactance per phase of a 4-pole, 50-Hz, 3-phase induction motor are 0.025 ohm and 0.12 ohm respectively. Make simplifying assumptions, state them and : (i) find speed at maximum torque (ii) find value of additional rotor resistance per phase required to give three-fourth of maximum torque at starting. Draw the equivalent circuit of a single-phase induction motor.
A 80 kW, 480-V, 60-Hz, six pole induction motor has a slip of 5 percent when operating at fullload conditions. At full-load conditions, the friction and windage losses are 300 W, and the core losses are 400 W. For full-load conditions, compute the induced torque,T-ind, in N-m.
A three phase, 50Hz, 6-pole squirrel cage induction motor runs at 960-rpm on full load. The stand still rotor resistance and reactance per phase are 0.01 ohm and 0.05 ohm respectively. Express the maximum torque developed in terms of full load toque. Find the slip at which the maximum torque occurs.
A 6-pole, 60-Hz, Y-connected, three-phase induction motor develops a torque (Td) of 250 N.m at a speed of 720 rpm. The rotor resistance is 0.4 Ohm/phase, and the stator winding impedance is negligible. A) What is the air-gap power? B) What is the rotor current refered to the stator? C) If the rotational loss is 1kW, what is the motor output power in hp?
A 3300-V, 50-Hz, 3-phase, 4-pole, star-connected induction motor has identical primary and referred secondary impedances of value 3 + j9 ohm per phase. The turns-ratio per phase is 3/I (stator/rotor), and the rotor winding is connected in delta and brought out to slip rings. Calculate: the full-load torque at rated slip of 5%; the maximum torque at normal voltage and frequency; the supply voltage reduction which can be withstood without the motor stalling; the maximum torque if the supply voltage and frequency both fall to half normal value; the increase in rotor-circuit resistance which, at normal voltage and frequency, will permit maximum torque to be developed at starting. Express this: as a fraction of normal R2and as (3) ohmic values to be placed in series with each of the slip-ring terminals and star connected.