Project: Induction Motor Protection System

Induction Motor Protection System The project is designed to protect an induction motor from single phasing and over tempera...

Induction Motor Protection System

The project is designed to protect an induction motor from single phasing and over temperature. Providing a protection system is very important in industries, using lot of motors such that production is not hampered owing to failure of any motor.

The basic idea for the development of this project is to provide safety to the industrial motor/pump/lift Motor etc. If any of the phases, out of the 3 phases is missing or if the temperature of the motor during operation exceeds the threshold value, motor stops immediately.

The system uses a 3-Phase power supply where three single phase transformers are connected to it. If any of the phases is not available the corresponding transformer stops supplying power to the circuit. This leads to one of the four relays getting switched OFF.

The main relay which is powered through a set of four relays gets disconnected because of one relay not being powered. Thus the main relay that delivers 3 phase supply to the motor gets disconnected. A thermistor is connected to the motor body to sense the temperature. If the temperature increases then supply to the fourth relay is disconnected.

Further the project can be enhanced by using current sensors for over load protection and phase sequence sensor for protecting the motor from applying wrong phase sequence. 

Picture credit: EDGEFX

HARDWARE REQUIREMENTS:

OPAMPs, Resistors, Capacitors, Diodes, Thermistor, Transformers, Regulator, Relays

Questions & Answers
1.What is induction motor protection?
Ans:Protecting the Induction motor from single phasing and over-temperature is known as induction motor protection.
2.What is the rating of motor used in this project?
Ans:A 3 phase, ¼ HP motor is used in this project.


3.Is single phasing protection available?
Ans:Yes, single phasing protection is available.

4.Why are 6 lamps used?
Ans:A series of two lamps are used to represent each phase. 2 lamps are connected in series to ensure safety.


5.What is the three phase induction motor rating to be used?
Ans:Three phase induction motor can be used, but limited up to 1 HP only as it uses a relay of 6A contact rating only. For higher HP just use a contactor of appropriate rating. The 230 AC coil of the contactor is powered in series from one of the contacts of the relay.

6.What is the formula for calculating smoothing capacitor value?
Ans:There is some approximated formula .Peak to peak ripple voltage = Load current in amps / (2*line frequency in hertz *capacitance in farads). But as rule of thumb for 1 A current 1000uF is best. Thus it is load dependent.


7.What to do when the lamp fails and what is the maximum lamp rating that can be used?
Ans:If the lamp fails one can use any lamp or bulb which is used in homes up to 100W. We suggest you to go for low watt bulbs.
8.In this project six bulbs are used but i want to use 3 phase induction motor instead. Is it possible? If yes then what will be the rating of that motor and what will be the cost?
Ans:You can use a three phase induction motor but limited up to 1 HP only as it uses a 3CO relay of 6 A rating only. For higher HP just use a contactor of appropriate rating the coil of which is driven by the relay on board.

You can request for demo presentation slides via Contact Us form with the link address of the post.

source: EDGEFX