A variable d.c. drive system is used to drive a fan which has the load characteristic T₁ x n², where T₁ is the load torque and n is the mecha- nical speed in rpm. When the motor runs at 600 rpm the back emf generated is 120 V and the current drawn by the armature is 28 A. Calculate the external resistance that must be added to the armature circuit to reduce the speed of the motor to 400 rpm. Neglect all electrical and mechanical losses of the motor including the armature resistance loss. [Ans: 3.21 22]

A variable d.c. drive system is used to drive a fan which has the load characteristic T₁ x n², where T₁ is the load torque and n is the mecha- nical speed in rpm. When the motor runs at 600 rpm the back emf generated is 120 V and the current drawn by the armature is 28 A. Calculate the external resistance that must be added to the armature circuit to reduce the speed of the motor to 400 rpm. Neglect all electrical and mechanical losses of the motor including the armature resistance loss. [Ans: 3.21 22]

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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