# Shakshat Virtual Lab

# INDIAN INSTITUTE OF TECHNOLOGY GUWAHATI

Blocked-Rotor Test

# Objective

This test is performed to determine the short-circuit current I_{sc} with normal applied voltage to stator; power factor on short-circuit; total equivalent resistance and reactance of the motor as referred to stator.The locked rotor test is done by mechanically holding the motor shaft from turning, and applying a reduced Voltage on the stator.

# Overview

Blocking the rotor from rotating is equivalent to making s=1 so that R2’(1/s-1)=0. This test is conducted by applying a low voltage to the stator so as to limit the current drawn to its full load value. At this reduced voltage, the core loss can be neglected but the effect of Xm has to be taken into account.

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