Orion Italia 50/51 - 50/51N relay...

[defreitas]

Hi guys, I was jut wondering if anyone would know the answer for this one...

While doing some HV protecion relay testing on a 11kV system (50/51 & 50/51N) I was faced wth the following problem.

The protection settings of the relay were IEC-C (Extremely Inverse) curve TMS 0.1 (O/C) and IEC-C (Extremely Inverse)curve TMS 0.2 (E/F).

All pick ups were perfect, but when I tried to do the times, I noticed that all the times were a lot slower then they were supposed to be (as per IEC-C).

After a little bit of research, I have found that all the times that I got as result of my test match the table on the relay manual.

As far as I understand even though the times match the manual the curves "are not correct", since they don't follow IEC standard, therefore they shouldn't have been called IEC curves on this paticular relay.

Has anyone faced the same issue?

It's an Orion Italia IPR-A relay, by the way.

PS: For checking my times I use a curve calculator that I developed on excel and matches times with all other relays that I have tested before (Sepam, Multilin, MiCOM).

I would appreciate any input.

Dan de Freitas

 

[7anoter4]

hi Dan,
I cannot see any difference to IEC 60255 standard.
For IMDT Relay according to IEC 60255 [for EIT/C curve] may be:
t(sec) = a . k / (((Fault/measured Current / Set Current) ^ b ) - 1)
where a=80 k=0.1[TMS] b=2
If we take Fault/measured Current / Set Current=2 then t=2.67 sec.
For Orion:
T=M/10*(K/(I/Ipu)^E-1)) with M=1 K=80 E=2
Then T=1/10*(80/(2^2-1))=2.67
The Spam time formula is:
Td(s)=k/((I/IS)^alpha-1)*TMS
Where k=80 and alpha=2, so it does conform to IEC.
At least, if one calculates it according to their instructions.
This is my opinion.
Regards

 

[defreitas]

Thank you for your reply "Zanoter4". I'm sorry for taking so long, I've been away and didn't have time to have a look at the forum.

Well, when comparing trip time results with the Multilin manual all the times are "10 times quicker" because of "M/10" on the formula.

I have checked my excel curve calculator and I'm sure it's correct (I've been using it for a long time now with no problems).

Today I'm doing the report for the job that I was doing when I realised this difference and I'm still puzzled.

Thank you for your time.



Dan de Freitas
Field Services Technician
AUSTRALIA

 

[slavag]

Hi.
Please find attached file with all needed data according to IEC60255-3 standard.
Best Regards
Slava

 

[defreitas]

After some more research this evening I came to realise that as Schneider does with Sepam, Orion italia does with IPR-A relays.

Some Schneider relays (mostly the old school ones as Sepam 2000 series) have the "TMS" as being the trip time at 10X setting current.

Orion plays the same game, probably utilising this method for some reason to make their life easier when doing the calculations in the relay electronics.

Which is all good and therefore I came to the conclusion that it's not wrong...

Now the only question is... If whoever designed the Power System I was testing took into consideration those relays, otherwise the protection discrimination is not correct.

I will have to advise my client about the concern.

Thank you very much for your help guys, you are champ...

Dan de Freitas
Field Services Technician
AUSTRALIA