“DESIGN OF PLC BASED CONTROL SYSTEM FOR 3PHASE SLIP RING INDUCTION MOTOR”
PROJECT REFERENCE NO. : 37S0268
COLLEGE
: HIRASUGAR INSTITUTE OF TECHNOLOGY, NIDASOSHI
BRANCH
: ELECTRICAL AND ELECTRONICS
GUIDE
: M P YANAGIMATH
STUDENTS : RAMANNA KULLOLLI
BHAGYASHRI NINGNURE
BHAGYASHRI BADIGER
VAJRAKUMAR
Introduction:
An induction motor(IM) is an ac machine which finds its extensive use in the field of
industrial and commercial areas. Induction motor may be of single phase or three phase, or
may be squirrel cage or slip ring type depending upon rotor structure. Usually slip ring IM’s
are preferred because of its advantages over squirrel cage IM’s. IM works on the principle of
Electromagnetic Induction. The main obstacle in working with IM is that it has high starting
current and poor starting torque. To overcome all these obstacles here we are proposing a
project in which case we are making use of Rotor Resistance Control Method the starting
torque will be improved and starting current can be reduced, also speed control can be
achieved. Here we are going to implement the above said idea using Programmable Logic
Controller(PLC).
Objective:
The aim of this project is to limit the starting current and increase the starting torque and to
control the speed of a three phase slip ring induction motor by rotor resistance control method
using Programmable Logic Control.
1
Block diagram:
Figure 1. Block diagram
The above block diagram shows the controlling of a three phase slip ring induction motor
using Programmable logic controller. It consists of PLC board which has input and output
ports, Contactors which are used for either to close or to open the terminals and one three
phase slip ring induction motor. The first two contactors are used to change the phase
sequence of power supply to change the direction of a motor as per our requirement. The
remaining two contactors are used to control the speed of a motor by cutting the resistance of
rotor of a motor.
Methodology:
In our project we are going to limit the starting current and we are controlling the speed of a
motor using PLC. As there are different methods to control speed and starting current but
here we are going to use resistance control method because of its advantages over other
methods. As explained in block diagram explanation, PLC can be easily adopted to control
speed, torque and current of a slip ring induction motor.
Advantages:
 This PLC based system is highly reliable.
2
 Without changing in any hardware connection just by simply changing the program in
the PLC,
 The motor can be made to run in any of the two directions and for any duration of
time.
 It is also possible to change the speed at any instant of time without altering any
hardware.
 This system not only reduces the starting current to a limit, but also develops High
starting torque which is required in many of the induction motor applications.
 This PLC based system requires less hardware compared to any microcontroller or
microprocessor based system.
Disadvantages:
 For small applications the initial cost is more.
 Efficiency is affected due to losses present in the resistors.
Applications:
 This can be applicable to run the lift, by changing the logic in a program and it can
also be used for any industrial applications.
 Programmable logic controllers(PLC) are widely used in industrial control because
they are inexpensive, easy to install and very flexible in applications. A PLC interacts
with the external world through its inputs and outputs
Sl.No.
REQUIREMENTS
COST
1.
Component cost
3000
2.
Module cost
15000
3.
Report cost
2500
4.
Other expenses
2500
5.
Travelling expenses
2000
TOTAL
25000
3
Results and conclusions:
By this project the speed of the motor is controlled as per the requirement. And in addition
the starting torque and starting current characteristics are improved using PLC.
4