PLC and Sensors Based Protection and Fault Detection of Induction Motors

1. SUBMITTED BY:-
Ahmed Soliman Alian Mohamed
Amit Kumar
Md. Sahzad Ansari
Taquee Equbal
Bachelor of Engineering
DEPARTMENT OF ELECTRICAL AND
ELCETRONICS ENGINEERING
Guided by : Mr. S. MATHAN KUMAR

2. Protection of an induction motor (IM) against possible
problems, such as overvoltage, over current, overload, over
temperature, and under voltage, occurring in the course of its
operation is very important, because it is used intensively in
industry as an actuator. IMs can be protected using some
components, such as timers, contactors, voltage, and current
relays. This method is known as the classical method that is
very basic and involves mechanical dynamic parts.
Computer and programmable integrated circuit (PIC) based
protection methods have eliminated most of the mechanical
components.
However, the computer-based protection method
requires an analog-to-digital conversion (ADC) card, and the
PIC-based protection method does not visualize the
electrical parameters measured.

3. In this proposed method for IMs, a new protection
method based on a programmable logic controller (PLC) has
been introduced. In this method, all contactors, timers and the
conversion card are eliminated. Moreover, the voltages, the
current, the speed, and the temperature values of the motor, and
the problems occurred in the system, are monitored and warning
messages are shown on the computer screen. This PLC-based
protection method costs less, provides higher accuracy as well as
safe and visual environment compared with the classical, and the
PIC-based protection systems.

4. Classical monitoring techniques for three-phase IMs are
generally provided by some combination of mechanical and
electrical monitoring equipment. Mechanical forms of motor
sensing are also limited in ability to detect electrical faults,
such as stator insulation failures. In addition, the mechanical
parts of the equipment can cause problems in the course
of operation and can reduce the life and efficiency of a system.
In computer based protection system, measurements of
the voltages, currents, temperatures, and speed were achieved
and transferred to the computer for final protection
decision. Although all the variables of the motor were

5. considered, usage of an analog-to-digital conversion (ADC) card
increases the cost and the size of the system.
A programmable integrated circuit (PIC) based protection
system, the solutions of various faults of the phase currents, the
phase voltages, the speed, and the winding temperatures of an IM
occurring in operation have been achieved with the help of the
microcontroller, but these electrical parameters have not been
displayed on a screen.

7. This method explains a PLC-based protection and monitoring
method for a three-phase induction motor. The new solutions for
various faults of the phase currents, the phase voltages, the speed,
and the winding temperatures of an IM occurring in operation
have been achieved with the help of a PLC. If only a PLC is used
as a protection relay for a system, it costs more. But the use of a
PLC can be the right choice if it is considered in an automation
system in order not to use extra microprocessor such as a PIC.

8. 3.1. CURRENT TRANSFORMER:
A current transformer (CT) is used for measurement of electric
currents. Current transformers, together with potential
transformers (PT), are known as instrument transformers. When
current in a circuit is too high to directly apply to measuring
instruments, a current transformer produces a reduced current
accurately proportional to the current in the circuit, which can be
conveniently connected to measuring and recording instruments.
A current transformer also isolates the measuring instruments
from what may be very high voltage in the monitored circuit.
Current transformers are commonly used in metering
and protective relays in the electrical power industry.

9. 3.2. VOLTAGE TRANSFORMER:
A voltage transformer (VT) is used for measurement of voltage.
Voltage transformers, together with current transformers (CT), are
known as instrument transformers. When voltage in a circuit is too
high to directly apply to measuring instruments, a voltage
transformer produces a reduced voltage accurately proportional to
the voltage in the circuit, which can be conveniently connected to
measuring and recording instruments. A voltage transformer also
isolates the measuring instruments from what may be very high
voltage in the monitored circuit. Voltage transformers are
commonly used in metering and protective relays in the electrical
power industry.

10. 3.3. PLC:
A programmable logic controller (PLC) or programmable
controller is a digital computers used for automation
of electromechanical processes, such as control of machinery on
factory assembly lines, amusement rides, or lighting fixtures.
PLCs are used in many industries and machines. Unlike general-
purpose computers, the PLC is designed for multiple inputs and
output arrangements, extended temperature ranges, immunity to
electrical noise, and resistance to vibration and impact. Programs
to control machine operation are typically stored in battery-
backed or non-volatile memory. A PLC is an example of a real
time system since output results must be produced in response to
input conditions within a bounded time, otherwise unintended
operation will result.

11. 3.4. INDUCTION MOTOR:
An induction motor (or asynchronous motor or squirrel-cage
motor) is a type of alternating current motor where power is
supplied to the rotor by means of electromagnetic induction. An
induction motor is sometimes called a rotating transformer
because the stator (stationary part) is essentially the primary side
of the transformer and the rotor (rotating part) is the secondary
side. It is of two types, squirrel-cage and slip ring induction
motor.
3.5. ENCODER:
It is used to encode the signal received from the induction motor
into a suitable form before sending it to the PLC.

12. 3.6. TRUE RMS TO DC CONVERSION CARD:
It is used to convert the RMS signal received from CT and PT
into DC signal before sending the signal to the PLC as it can
accept only DC signal.
3.7. SENSOR:
It is used to sense the various signals such as temperature signal,
rotor speed signal etc. from the induction motor and then send it
to the PLC.

13. 4. ADVANTAGES OF PROPOSED METHOD:
• Low power consumption
• Maximum efficiency
• Less cost
• Easy implementation
• Reduces the man power
• Provides higher accuracy
• Provides safe and visual environment
• Faster operation
• More reliable

14. 5. PROPOSED APPLICATIONS:
•In various industries such as power plants, steel plants etc.
•In laboratories

15. 6. LITERATURE REVIEW:
This proposed project has been taken from the “IEEE
TRANSACTIONS ON ENERGY CONVERSION, VOL. 23,
NO. 3, SEPTEMBER 2008” which is the paper of Mr. Ramazan
Bayindir, Member, IEEE, Mr. Ibrahim Sefa, Member, IEEE, Mr.
˙Ilhami Colak, Member, IEEE, and Mr. Askin Bektas who all are
from Gazi university, Turkey.
For doing this project, I would like to thank the authors of this
paper, the Principal, the Dean (Electrical Sciences), my Project
Guide, my Project coordinator, my Department Faculties and my
Friends who helped in collecting the related materials and
carrying out this project. I have also used internet and my college
library for collecting related materials.

16. 7. REFRENCES:
•Mr. Ramazan Bayindir, Member, IEEE, Mr. Ibrahim Sefa,
Member, IEEE, Mr. ˙Ilhami Colak, Member, IEEE, and Mr. Askin
Bektas, Gazi University, Turkey “IEEE TRANSACTIONS ON
ENERGY CONVERSION, VOL. 23, NO. 3, SEPTEMBER
2008”.
•U.A. Bakshi and M.V. Bakshi. “Electrical Machines II”.
•Wikipedia
•Science alert (www.scialert.net)