REX 010 and REX 011 Gen Stator Prot 3

[bdf5526]

Hi, anybody got experience working with the REX 010 and REX 011 module which used for Gen Stator E/F protection(59GN-95%, 64GN-100%, and 64GN)? This equipment is belongs to ABB. Why they need to inject pulse voltage at the generator neutral point?

Thanks in advance.

 

[slavag]

Hi.
It's 100% injection principle.
In case of stator earth fault near to the neutral point standard 95% do not sensetive.
more from than, you can see earth fault on the standstill generator.
Work fine.
Best regards.
slava

 

[bdf5526]

Hi slavag, thanks for the reply. After googled about this injection principle I found that the 95% stator E/F might not see the winding to earth fault when its closer to neutral point as you said. I belive I need more home work on this.

 

[slavag]

Hi Bdf5526.
You have a good explanation at the manual of REG216.
Please see attached great document of Mr. Mozina,
Are you need provide design, commissioning of REG with REX?
Best Regards.
Slava

 

[bdf5526]

hi slavag, soon I need to commission both, the REG216 and REX module. Just curiouse and wanted to know as much as possible about this. You are right the manual explains everything. Do you know any equevelent protection system from AREVA?. Which one is easy to handle?. Thanks.

 

[bdf5526]

hi slavag thanks for the valuable attachement from Mr.Moniza.

 

[slavag]

Hi Bdf. On this year i commissioned 2 such systems.
Please take in account: if you havent expirience with REG216 and REX DON'T TRY COMMISSIONED IT BY YOURSELF.
You must take some course in ABB and first commissioning provide with some expir. guy.
I don't know where you are.
You have good centers in Euoropa: ABB Swiss ( Baden), ABB Holland and ABB German. As far, as I know ABB South Africa have good guys too.
About Areva, I don't know, it;s old Alstom relays.
Beckwith and Simens(maybe) have such sytems.
Why made this cubicles and design? What is size of generator?
Regards.
slava

 

[bdf5526]

Hi slavag, actually I will be getting some support from an experienced person for this coming commissionig. The whole panel is from ABB and it comes in a package. The generator size is 500MVA.

regards,
bdf

 

[slavag]

OK Bdf.
500MVA is generator...
REX's need for the rotor and stator E/F?
You have local support, is good and important.
Are you familar with CAP2-316 , HMI of REG216?

Very important point: SAFETY, REX's inject low voltages signal on the neutral point after neutral trafo, that means
on the stator of generator you will have high voltage ( 50V x grounding trafo ratio). Please take in account and turn off power supply of REX at teh panel REG.
Regards.
Slava

 

[bdf5526]

Hi slavag, here the REX only used for the stator earth fault. For the rotor E/F protection, excitation has its' own protection system and there is a feedback signal coming from excitation system to the protection panel according to the drawing. The generator using resistance grounding and seems like REX will be injecting at the star point. No earthing transformer used. When we will be using earthing trafo instead of neutral point injection?. Thanks for the support.

 

[slavag]

It's OK.
strange for me, 500MVA with resistance grounding, I think it's Erop. mnf.
No problem with Rotor E/F, is less work for your.
Please send to Forum part of this connection ( Stator E/F) with REX. usually it's one page. REX have two option, primary and secondary injection. I would like see , what you have and recommend a few important points.
regards.
Slava

 

[bdf5526]

Hi, sorry for the delayed reply. Yes, this is Europe mnf. Attached is the drawing for the NER for the generator(sorry for the quality I had to use my camera, the scanner is down). Somehow the REX has been calibrated for the 100% E/F protection with the help from my friend. I am expecting for your valuable comments on this.

Thanks.

 

[slavag]

Hi.
It's primary connection , that means, it's REX011 instead REX011-1(2)as on the drw, that used for the secondary injection type.
Resistors seems OK, typical value is 150 and 1000 Ohm, I hope designer calculated this size.
Somehow calibrate:
1. are you provide both tests on the standstill generator: one for MTR value and second for the REs value,.
2.Are you provide test of curve.
3.Are you meas direction of Us and Ui, it must be same direction.
terminals 10,11 on the REX011 aren't used , are for the rotor E/F injection.
If possible , could you please attac valible report, if you haven't standard form, I will attached here.
Good Luck.
Slava

 

[bdf5526]

Hi, yes we did test for MTR value and REs value. We did the test curve for the measured (at REG216) and actual resistance at neutral point as well. But we did not do the measuring of the direction of Us and Ui. I think this test is not required by the client.(i am not sure need to check again). If you know how to test the direction of the Ui and Us it would be helpfull for me to know.

Thanks in advance.

 

[slavag]

Hi Bdf.
Congratulation!!!!!Your first 100% stator E/F.
I very happy for you.
If you tested those 3 points ( MTR, Res and curve) test of direction no needed.
Are curve OK? it's something like to saturation curve ( I mean form of curve), usuallu after 17-19kOhm it's like to saturation.
Alarm about 10kOhm, trip about 1kOhm.
Best Regards
Good Luck
Slava

 

[bdf5526]

Hi slavag, yes you are correct the curve is something like a mag curve. The alarm was about 10kohm and the trip is about 1 kohm. I have attached the curve.

Thanks for the kind advice. If you need to do the direction of the Ui and Us how would you do?

 

[slavag]

Hi Bfd.
Curve isn't seems, sorry.
What was calculated MTR and what is tested value?
What was Res and tested value?
I strongly recommend back to test.

For direction test you need scope with two channels.
Possible used on-line analog meas of REG216, but it's difficult explain via forum or e-mails.
Wave of Ui asnd Us must be i same direction, if not, you cross wiring on the terminals in the cubicle.
Best Regards.
Slava

 

[bdf5526]

Hi slavag,

Sorry for not reply for quite some time and as you asked;

caluculated MTR (measuring transformer ratio) value: N12/N11 = (21000/sqrt3) / 100 = 121.24

measured MTR value by REG is 127.3

Calculated Res Value is 900 ohm.

Measured Res value by REG is 760 Ohm.

Accordng to my trainer this is good enough and we just use this value for the documentation.

Together have attached pic of the curve of the resistance. X' axis is the actual value of the resistance placed in Neutral Point and the Y' axis is the measured resistance by the REG 216. Your comments is hightly preciated. Now the unit is running and we even test the 100% earth fault (during generator no load test) protection. The test was ok.

 

[slavag]

Hi Bdf5526.
Thanks a lot for the feedback.
Yep, is good result.
I'm really happy for you.
Good Luck and All best.
Slava