The speed of a shunt-wound d-c motor may be efficiently regulated by an external field rheostat because such a rheostat A. lowers the armature current. B. varies the field current regardless of load. C. causes the speed to vary with load changes. D. adds resistance in parallel with the field.

The speed of a shunt-wound d-c motor may be efficiently regulated by an external field rheostat because such a rheostat A. lowers the armature current. B. varies the field current regardless of load. C. causes the speed to vary with load changes. D. adds resistance in parallel with the field.

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter5: Resistors

Section: Chapter Questions

Problem 1PA

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Concept explainers

Speed control of motor

Speed control by DC motor-speed controller is required to realize variable speed drive. Whenever a motor drives a particular load, it is called drive, and variable speed drive refers to a load requiring variable speed. All this is obtained by a DC motor speed controller.

Question

The speed of a shunt-wound d-c motor may be efficiently regulated by an external field rheostat because such a rheostat

A. lowers the armature current.
B. varies the field current regardless of load.

C. causes the speed to vary with load changes.

D. adds resistance in parallel with the field.

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