Page 313 - Electronic Mechanic - TP - Volume - 2

ELECTRONICS MECHANIC - CITS

EXERCISE 211&213: Change the direction of rotation of
Induction and perform Jog operation

on a motor

Objectives

At the end of this exercise you shall be able to:
• to connect Contactors and relay
• to change the direction of a three phase induction motor rotation
• to perform Start, stop , Run and Jog on a 3 phase induction motor.

Procedure

To change the direction a three phase induction machine rotation, two of its phases needs to be exchanged, thus
changing the phase sequence form, say ABC to CBA.
This can be accomplished by using two contactors, one for the forward or CW rotation and one for the reverse or
CCW rotation.

The forward and reverse contactors are mechanically interlocked i.e., if one of them is closed the other cannot
close. This is done to avoid dead short circuit in case both the contactors closing simultaneously.
Also electrical interlocking could be provided using the contactors control contacts
Instruments & Equipments

Name Figure

Three phase induction motor

Main and Sub feeder isolating circuit breakers
(board #5)

296