mopn motor protection relay

Hi friends

I have to test MOPN 01 motor protection relay from ALSTOM.It monitors current in two phases only and the earth fault current is obtained from a corebalance ct or residually connected cts.



Here I have detailed my problems and the text is slightly long , but I would appreciate if u could pls take some time and read it to help me out. I thank all of those who chose to open it and read it. Thank u in advance.


My problem is that I do not have a current injection set that could give me two currents at a phase angle of 120 deg or a phase shifter that I could use for the purpose.
I have only one single phase current injection set. Hence I am confused about simulating the conditions for test with a single phase unit. Moreover I have never tested this relay before , so I request someone with deeper knowledge to please look at it and give comments.

CONSIDER THE FOLLOWING DATA

I thermal .88 In
Te1 9 minutes
Te2 Te2=Te1
Tr(cooling time constant) 45 minutes
E1(start inhibit threshold- % of thermal capacity) 40% -motor once stopped will not restart until the thermal capacity is above this value
E1(start inhibit threshold-% of thermal capacity) 90% - relay will give alarm when this amount of thermal capacity is spent
Ph Isc- Ph short circuit protection ( provided for protection against shortcircuit at the motor terminals) 1.2 starting current
Io ( earth fault setting ) .4 In
I2 (Negative sequence setting ) .2 In
Is ( starting current threshold) 3*I thermal
Tb (Starting time) 6.0 seconds
Tb1(Time to trip on stall ) 1.6 seconds



I have decided to test the relay in the following manner and I request you to kindly check if there is a problem

1. To check the earth fault unit
Inject a single phase current equal to earth fault setting in the designated terminals and verify that the trip occurs after the set time delay
2. To check the short circuit current threshold Isc
Inject a current equal to 1.2 times starting current in any one of the phase monitoring units of the relay and verify that the relay picks up after 100ms(given fixed value by the manufacturer)
Or
Inject 1.2*starting current into both of the phase monitoring units connected in series and verify the trip as said above
3. To check the negative sequence unit
Inject 0.2In into any one phase monitoring unit and the relay should pick up after a fixed time delay (if any).
4. To check the cold thermal curve
Select a value of the current from the cold curve and inject a single phase current in both the phase monitoring units connected in series and verify the time from the curve.- to be done for at least three values.
5. To check the thermal threshold E1
Here I do not know , how much current I should inject in the phase monitoring units of the relay. I should ideally spend 50% of the thermal capacity and verify that the relay does not allow me to restart unless the remaining thermal capacity is 60%.
6. To check the thermal threshold E2
The problem here is similar to the problem mentioned for E1
7. Startup threshold Is.
Inject a current equal to the startup threshold through both the phase monitoring units of the relay connected in series. The relay should pickup after the startup time elapses ( 6 seconds in this case)
8 Rotor stall delay
Inject a current greater than the startup threshold through both the phase monitoring units of the relay connected in series. The relay should pick up after the fixed time delay of 1.6 seconds.

Thank u all once again.

isoA120

Overload time constant

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When the overload constant of a motor is expressed in minutes,(let us say 10 minutes) does it mean that the motor reaches it's 100% thermal capacity when the motor is subjected to some amount of overload (example 110%)for a period of 10 minutes.I shall be very thankful if someone can make it clear to me.

Thank u in advance

merajdab

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