Chapter 12, Problem 1RQ

To determine

The average amount of current flowing in two remaining phases.

Explanation of Solution

Given:

The name plate current of three-phase motor is 56 A.

Calculation:

A failure phase occurs when power is lost from a three-phase motor power supply line. The motor is still running, but it draws excessive current. This phenomenon is known as Single phasing. Single phasing causes a current increase of 173% in average of both phases which remain energized in a three-phase motor.

Calculate the current flowing in two remaining phases:

  $\begin{array}{c}{\text{I}}_{\text{avg}}=173\%\text{of}\text{I}\\ =\frac{173}{100}\times \text{I}\\ =\text{1}\text{.73}\times \text{56}\text{A}\\ =96.88\text{A}\end{array}$

Thus, the average amount of current flowing in two remaining phases is $\underset{\_}{96.88\text{A}}$.