College of Engineering and Technology
Electrical and Control Engineering Department
Automated Industrial Systems I
EE512
EX3: Forward/Reverse Motor Operation
Lecturer name: ……………..…………………………………………………………………………...….……
Student name : .…………………………………………………………………………………………………..
Registration # : …..……..…………………………………………………………………………………………
Prepared By: Prof. Hamdy Ashour
September 2014
Eng. Ahmed Al Bashir
Mr. Mohamed Samir
Mr. Wael Mohamed
1|Pa
ge
Experiment 3
Forward/Reverse Motor Operation
1- Objective
To change the direction of a three phase induction motor rotation.
2- Theory
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.
3- Instruments & Equipments
Three phase induction motor
Main and Sub feeder isolating circuit breakers
(board #5)
2|Page
Power and control circuits fuses
(board #6)
Three phase mechanically interlocked
contactors
(board #4)
Overload
(board #3)
Indicating lamps and Pushbuttons
(board #1)
3|Page
4- Connection
L1
L2
L3
Circuit Breaker
C.B
Q1
Fuses
F1 F2 F3
Contactor
K4
Contactor
K3
Mech. Interlocked
Overload
F5
T1
T2
T3
3φ
IM
Power Circuit
4|Page
Q2
L1
C.B
Fuse
F6
11
Pushbutton
Stop
S0
12
95
Over Load
F5
96
13
13
13
13
Start
Start
S1
S2
Pushbutton Pushbutton
14
14
K3
14
21
14
21
K4
K3
22
X1
K4
22
A1
A1
K3 Contactor Contactor K4
Coil
Coil
H1
X2
A2
A2
Fuse
X1
H2
X2
F7
Q2
N
C.B
Control Circuit
Power and Control circuits connections diagram
5|Page
5- Procedure
a.
b.
c.
d.
e.
Connect the circuits as shown in the diagram.
Switch on the main and sub feeder isolating circuit breakers (Q1, Q2).
Use the start and stop pushbuttons for motor operation.
Press the forward direction pushbutton.
Stop the motor and then press the reverse direction pushbutton to change the rotation
of the motor.
6- Connect the power and control circuits on the following figure
7- Add your own comments
……………………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………………….………………
8- Use internet resources to provide advantages, disadvantages and then discuss different
applications of forward/reverse motor operation circuit
……………………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………………………………….
6|Page