1. Comparison between
MPR300 & Bimetal relays

2. Motor Protection Relay
Qu. What are the basic Protections required to low size
motor?
Ans.The protection required to lower size of the motor are
as follows,
1.Thermal Overload.
2.Earth Fault.
3.Single Phasing .
4.Phase Sequence reversal.
5.Load Unbalance.
6.Under Current.
7.Locked Rotor.

3. ??? Is there any relay in the universe which can provide all the
protections to my motor?
???

4. YES
L&T Make
MPR300

5. Traditional Method to protect the MotorF
Normal connection
1.Fuse.
2.Thermal Bimetallic Relay .
3.Contactor.
4.Motor. TR
Protection Offered thru
1.Bimetallic Thermal overload Relay C
Type of Protection offered by the scheme
1.Short Ckt.
2.Over Load M

6. Modern Method To Protect The MotorF
Just Replace B.M.R.with MPR300 .
MPR300
Protection offered thru
1.MPR300 .
Type of protection offered by Relay
1.Thermal Overload.
2.Lock- rotor.
3.Earth fault.
4.Single Phasing .
5.Phase Sequence Preventer.
6.Load Unbalance.
7.Under Current. C M

7. Why People Should Go For MPR300
Bimetallic Relay
MPR300
Qu.Can you get the cause of tripping with B.M.R.?
Qu.Are you getting Earth fault protection /Phase reversal preventer/unbalance load /Under current thru B.M.R.?
Qu.Is it economical to put no. of relays for no. of protection in comparison to put only one relay & get all the protection?
Qu.Do you know that B.M.R.can give nuisance tripping in hot weather,& interrupt your production & in the cold season it will take longer time to trip?
Qu.Do you know after tripping and rectification of fault you can not run the motor until & unless the bimetal strip cools down (wasting of precious production time)?
Qu.Whatever protection you are getting thru the B.M.R., are they adequate to protect the motor?
Qu.can u choose the O/L Curve as per requirement?
Qu.In B.M.R. is there any means to say that there is O/L,so u can reduce your load and save your motor to trip(very important in continuous Industries)?
Qu.Can you test the reliability of the relay without interrupting the process ?
Qu.Are B.M.R. always trips on right time ?

8. Comparison between Bimetallic relay ---MPR300
Principle
1.Material Heating.
(old method)
Principle
1.By sensing acual Motor current
with Microprocessor harware
(Modern Technology)
Reliability
Poor accuracy &
repeatability
Reliability
Very high accuracy &
reliability

9. Comparison between Bimetallic relay ---MPR300
No. of protection
1.Overload
No. of protection
1.U/ C.
2.L/ R.
3.E/ F.
4.Single Phasing .
5.phase sequence Preventer
6.Unbalance load
7.Thermal Over Load (with thermal Memory ).

10. Comparison between Bimetallic relay ---MPR300
Indication
1.Bimetallic Relays are dumb relays.
They will never say the cause of tripping.
Indication
1.This relay is a intelligent relay.
Thru the LED it will tell you the Cause of tripping.

11. comparison between Bimetallic relay ---MPR300
Dual loss of Money
1.Shut Down Time = Time to locate the fault + Removal of fault condition.
2.U will lose your precious time to locate the fault .
3.Production loss will be very high.
Dual saving of Money
1.Since u will get the cause of tripping as soon as fault occurrence.
2. You can save the time to locate the
fault.
3.The chances of damages due to faults other than over load is eliminated.
4. Production loss will be very low.

12. Comparison between Bimetallic relay ---MPR300
Response Time
1.The response time of
bimetallic relays are too
much . Sometimes relay
will not trip and motor
Will burn.
Bimetallic relays are also
affected by Ambient
Temperature. In the case
of hot seasons relay may
trip with out any fault.
Response Time
1.Lock Rotor = 1sec.
2.Under Current = 3Sec.
3.Earth Fault = 300Mili Sec.
4.Negative sequence = 3Sec.
5.Over Load = As per the curve
selection .
Not affected by Ambient temperature

13. Comparison between Bimetallic relay ---MPR300
Reset Time
1.In case of any fault relay
will heat up and trip the
contactor , but u will not be
able to run the motor again until & unless the relay cools down.
So production time loss.
Reset Time
1.The Relay contacts are manual reset so after removing the fault u can run the motor any time no need to wait.
Saving of time. More production

14. Comparison between Bimetallic relay ---MPR300.
Extra Facility
1.There is no extra feature given by relay.
Extra Facility
1.Curve Selection for O/L according to suitability to your motor.
2.Under Current (in many process it is required).
4.Earth Fault.
5.Reset Push button.
6.Test Push button.
7.Dedicated LED to show the individual fault

15. Comparison between Bimetallic relay ---MPR300
No. of contacts
1.Only one NC contact.
No.of contacts
1.Two contacts
a)NC to trip the contactor.
b)NO to give remote alarm

16. Comparison between Bimetallic relay ---MPR300
Test facility
1.No on line test facility of relay.
Test facility
1.On line testing facility is available,
u can test the relay without interrupting the process

17. Comparison between Bimetallic relay ---MPR300
Relay Range
1. B.M.R.’s Range
are in between of
1 – 1.66 Im.
2. Limited use.
Relay Range
B.M.R.’s Range is in between
Im.
2. Wide range for use.

18. Comparison between Bimetallic relay ---MPR300
Matching Problem
1.Always problematic to connect the relay with contactor.
Test facility
1. Very easy to connect.

19. + MPR300 B.M.R. Lot of additional Feature = 1.Economical (all in one )
PHASE SEQ.
PREVENTER +
Lot of additional Feature =
Single phasing
preventer
MPR300
EARTH FAULT
RELAY
1.Economical (all in one )
MOTOR
2.Space Efficient (all in one)
3.Additional Feature

20. R Y B N
How To
Install
Contactor Coil
MPR300