Design and Fabrication of multiple induction motors automatic starter via liquid rheostat

Project Title

Design and Fabrication of multiple induction motors automatic starter via liquid rheostat

Project Area of Specialization Electrical/Electronic EngineeringProject Summary

Induction Motor is a widely used machine round the globe but it has a major drawback that is, it requires 6-8 times it’s rated current at the start which makes it uneconomical and that is why industries are using starters to get rid of this issue and every motor requires it's own starter so far. So, in this project to make it more economical we have designed a logic circuit to start more than one motors with one starter by using liquid Rheostat. We have designed a logic in which by using magnetic contactors and timer relys we have used a single liquid starter with variable resistance range to use it for multiple motors.

Project Objectives

• The main motive of this project is to use one starter for multiple motors.
• Starting current will be controlled for multiple motors.
• This will be very economical for industries as a single starter will be used for more than one motors then the cost of separate starter for every motors will be nullfied.
• Switchgear will be designed for rated values and not for starting current values hence cost effective.

Project Implementation Method

Basically we are using a logic circuit using timer relays and magnetic contactors to perform this operation for more than one motors. As we know that liquid rheostat is also being used as a starter for induction motors in different industries. But they just use one liquid starter for one motor. The one we are using has the capability to start more than one motors, one after the other.

For that we have used a logic circuit in which we have used three magnetic contactors and one timer relay for one motor and three magnetic contactors and one timer relay for the other motor.

Two of the three contactors for one motor will add the starter in the start of motor and then the third one will be used to bypass the starter after it will be used to start the motor.

The timing of these contactors is controlled by timer relay. We will set the time of timer relay according to the time that a motor require to gain its rated rpm and during that time two magnetic contactors add rheostat in the circuit and once the motor will achieve its rated rpm the third contactor bypass the motor with the help of timer relay and the rheostat will be all set for the second motor.

As for as the resistance of rheostat is concerned we will set the maximum resistance of water by taking the maximum resistance of heaviest motor and then for the rest of the motor the rods depth will be set according the resistance of the second heaviest motor and so on.

Benefits of the Project

The core benefit of this project is, it is economical. Since every motor is using its own starter so far and after that motor is being started and that starter has no use. So industries are basically pay extra money for an equipment which has less use but it has initial as well as running maintenance cost. To get rid of that extra cost we have designed this starter which not only save initial cost as well as it requires less maintenance because of simple phenomenon which is more equipment more maintenance cost and vice versa.

It also has the same benefits that a simple starter is providing that is it also save money as low power switch gears are being used having said that, it also has a benefit that we are not using any microcontroller or any other electronic device other than PMDC motor's module which means this circuit is hard and robust which will eventually requires less maintenance.

Technical Details of Final Deliverable

• Our final product will be a capable of starting more than one motors with one starter one after the other.
• It will be fully automatic without any human interference.
• All the operator have to do is to switch on the motor when needed.
• For each motor there will be a breaker, a timer relay, three magnetic contactors.
• The liquid rheostat that we are using has a stand, three rods for three phases, three water jars, salt as per needed, those three rods are attached to a insulated rod, which has small tires at the side to slide the rods in the water to vary the resistance, a PMDC motor move the slider up and down and a PMDC module to move the motor clock and anti clock wise when needed. Two limit switches are being used to restrain the upper and lower limit of the slider.

Final Deliverable of the Project Hardware SystemCore Industry ManufacturingOther IndustriesCore Technology OthersOther TechnologiesSustainable Development Goals Decent Work and Economic Growth, Industry, Innovation and InfrastructureRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	60170
3 phase Induction Motor(1hp))	Equipment	1	9000	9000
3 phase Induction Motor(0.75hp))	Equipment	1	7500	7500
MCB	Equipment	2	600	1200
Timer Rely	Equipment	2	450	900
Timer Rely Base	Equipment	2	60	120
Magnetic Contactor	Equipment	6	500	3000
Indicating Light	Equipment	2	50	100
7/29(25 meter)	Equipment	1	2500	2500
Wire Connectors(3 dozen)	Equipment	3	100	300
male to female(1 dozen)	Equipment	1	100	100
male to male(1 dozen)	Equipment	1	100	100
female to female(1 dozen))	Equipment	1	100	100
junction wires(3 meters)	Equipment	1	100	100
Adopter	Equipment	2	1500	3000
Non rechargeable Battery cell	Equipment	4	25	100
Dc motor module	Equipment	1	500	500
12 volt DC motor	Equipment	1	400	400
Liquid rheostat	Equipment	1	12000	12000
Traveling cost	Miscellaneous	1	2500	2500
Wooden Mat	Miscellaneous	1	2000	2000
Tape	Miscellaneous	5	50	250
paint spray cane	Miscellaneous	2	500	1000
limit Switch	Equipment	2	1000	2000
Bread Board	Miscellaneous	1	200	200
Report Hard Form	Miscellaneous	1	400	400
Final Report hard binding	Equipment	3	3000	9000
Screws (2 dozen)	Miscellaneous	2	150	300
water tank	Equipment	3	200	600
Aluminum rods	Equipment	3	200	600
Threaded rod	Equipment	1	300	300