A direct current motor is connected to a 250-volt DC supply. The armature has a current draw of 165 amperes when operating at full load. You have been assigned the task of connecting two resistors in the armature circuit to provide speed control for the motor. When both resistors are connected in the circuit, the armature current is to be limited to 50% of the full-load current draw. When only one resistor is connected in the circuit, the armature current is to be limited to 85% of full-load current. Determine the ohmic value and min-imum power rating of each resistor.

A direct current motor is connected to a 250-volt DC supply. The armature has a current draw of 165 amperes when operating at full load. You have been assigned the task of connecting two resistors in the armature circuit to provide speed control for the motor. When both resistors are connected in the circuit, the armature current is to be limited to 50% of the full-load current draw. When only one resistor is connected in the circuit, the armature current is to be limited to 85% of full-load current. Determine the ohmic value and min-imum power rating of each resistor.

Electric Motor Control

10th Edition

ISBN:9781133702818

Author:Herman

Publisher:Herman

Chapter44: Use Of Reduced Voltage For Starting

Section: Chapter Questions

Problem 4SQ

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A direct current motor is connected to a 250-volt dc supply. The armature has a current draw of 165 amps when operating on a full load. You have been assigned the task of connecting two resistors in the armature circuit to provide speed control for the motor. When both resistors are connected in the circuit, the armature is to be limited to 50% of the full-load current draw. When only one resistor is connected in the circuit, the armaturecurrent is to be limited to 85% of full-load current. Determine the ohmic value and minimum power rating of each resistor.
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