A shunt motor connected across a 400 V supply takes a total power of 8 kW and runs at 600 rev/min. The filed coil and armature has a resistance of 200 N and 0.6 N, respectively. Calculate: (i) The field current and the armature current, (ii) The back e.m.f., (iii) The values of the armature current and of the speed if the magnetic flux is reduced by 30% and the load torque is increased by 40%.

A shunt motor connected across a 400 V supply takes a total power of 8 kW and runs at 600 rev/min. The filed coil and armature has a resistance of 200 N and 0.6 N, respectively. Calculate: (i) The field current and the armature current, (ii) The back e.m.f., (iii) The values of the armature current and of the speed if the magnetic flux is reduced by 30% and the load torque is increased by 40%.

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

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Concept explainers

Stator and Rotor Magnetic Field

The stator and rotor magnetic field is the resulting magnetic field generated by a system of coils that are symmetrically aligned. They are supplied with polyphase currents. The magnetic field is generated by poly-phase (two or more phases) current or single-phase current. In the latter case, two field stator windings are supplied and two resulting electromagnetic fields are generated beyond the stage.

Question

A shunt motor connected across a 400 V supply takes a total power of 8 kW and runs
at 600 rev/min. The filed coil and armature has a resistance of 200 N and 0.6 N,
respectively. Calculate:
(i) The field current and the armature current,
(ii) The back e.m.f.,
(iii) The values of the armature current and of the speed if the magnetic flux is
reduced by 30% and the load torque is increased by 40%.

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