A 140 V, DC shunt motor drives a constant-torque load at 1100 rpm speed. The armature andfield resistances are 0.9 2 and 155 N, respectively. The motor draws a line current of 10.5 A atthe given load. Answer the following questions.1- Calculate the resistance that should beadded Radd N to the armature circuit to reducethe speed by 85%.RaddRaddΩ2- Calculate the efficiency of the motor withoutthe added Radd N if the rotational losses isM1Vtequal to 147 W.%TEa3- Calculate the efficiency of the motor with theadded Radd Nif the rotational losses is equal to147 W.%4- Calculate the resistance that must be added to the armature circuit to operate the motor atthe holding condition.Radd|||

Given V=140 V N=1000 rpm Ra=0.9 ohm Rsh =155 ohm IL=10.5 A

A 140 V, DC shunt motor drives a constant-torque load at 1100 rpm speed. The armature and field resistances are 0.9 N and 155 N, respectively. The motor draws a line current of 10.5 A at the given load. Answer the following questions. 1- Calculate the resistance that should be added Radd 2 to the armature circuit to reduce the speed by 85%. Radd Radd 2- Calculate the efficiency of the motor without the added Radd SN if the rotational losses is M1 Vt equal to 147 W. n = % 3- Calculate the efficiency of the motor with the added Radd Nif the rotational losses is equal to 147 W. |% 4- Calculate the resistance that must be added to the armature circuit to operate the motor at the holding condition. Radd

A 140 V, DC shunt motor drives a constant-torque load at 1100 rpm speed. The armature and field resistances are 0.9 N and 155 N, respectively. The motor draws a line current of 10.5 A at the given load. Answer the following questions. 1- Calculate the resistance that should be added Radd 2 to the armature circuit to reduce the speed by 85%. Radd Radd 2- Calculate the efficiency of the motor without the added Radd SN if the rotational losses is M1 Vt equal to 147 W. n = % 3- Calculate the efficiency of the motor with the added Radd Nif the rotational losses is equal to 147 W. |% 4- Calculate the resistance that must be added to the armature circuit to operate the motor at the holding condition. Radd

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 13RQ: A squirrel-cage induction motor is operating at 1175 RPM and producing a torque of 22 Ib-ft. What is...

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