SEL Relay Event Logs Meaning 4

[NorEE]

Sirs,

Im working in a power plant using SEL relays and would like to know how to correctly read event logs.

Please advise me on how to effectively get the right information out of our relays.

Thanks so much!

 

[davidbeach]

What are you seeing that you don't understand?

 

[dpc]

I'd start with the relay manual. The SEL website has quite a few articles on dealing with event reports, although these seem to have diminished a bit as they are trying to get people to attend their training classes.

Your SEL field engineer should be able to help answer any specific questions.



David Castor

http://www.cvoes.com

 

[NorEE]

To both sir davidbeach and dpc,

Thank you for taking notice of my post.

sir david

the SEL display is this:
(date/time omitted)
Event AB
Location 20.45
Freq. 60.2
Shot 3P=0
BK1 OPEN
FAULT Quantities(kV/A)
Va 6 64.1deg
Vb 6 -48.3deg
Vc 7 -172.3deg
Ia 200 0.0deg
Ib 222 -156.6deg
Ic 89 88.6deg
Ig 1 164.0deg

Backround:

We are operating our CoGen around 8 mos. as of today in island mode supplying power and steam to our production plant.

We supply power thru 13.8kV transmissions lines and then voltage is being 'stepped down' through two 3MVA transformers at production side. In between our Tie feeder and the two transformers we use reclosers. One for each transformer and another one just after our Tie Feeder VCB.

Last Oct. 3, when we attempted to resume power supply to production (after scheduled shutdown)particularly when we closed one of our transformer reclosers the SEL relay opened the tie feeder VCB (no trip indication). This same condition happened twice before we decided to first close the other transformer's recloser. Result was normal.

This was how we survived from from our big boss's 'big voice.'

Up to date, plant is running normally.


sir DPC

Ive been trying very hard to understand the manual but unfortunately to little avail (i will continue to struggle until i get the concept)
On your suggestion, I emailed sir Marc Palmer of SELINC.com, an applications engineer and his reply is for me to send him the complete report from the relay. I will do so very soon.


Again, thank you both for your replies.

 

[Janol]

the SEL display is this:
(date/time omitted)
Event AB phase A to phase B line-to-line fault
Location 20.45 fault occurs 20.45km from plant A
Freq. 60.2
Shot 3P=0 Not sure
BK1 OPEN CB open
FAULT Quantities(kV/A)
Va 6 64.1deg Amp/kV and phase angle
Vb 6 -48.3deg
Vc 7 -172.3deg
Ia 200 0.0deg
Ib 222 -156.6deg
Ic 89 88.6deg
Ig 1 164.0deg

Hope it helps you.

 

[jghrist]

If the relay is on the primary side of a delta-grd wye transformer, this probably indicates a Ø-grd fault on the secondary of the transformer. A Ø-grd fault on the secondary would look like a Ø-Ø fault on the primary. The meaning of the location depends on the relay settings. Settings will include a line impedance per unit length which the relay uses to determine distance. If there is a transformer between the relay and the fault, then the location will not have any meaning.

You should also be able to download a detailed event report showing the currents and voltages for several cycles before and after the fault (depending on the relay settings) at 4 or 16 samples per cycle. The event reports can be downloaded with simple terminal program like Microsoft Hyper Terminal or with SEL AcSELerator Quickset software (free download from their website). The events can be viewed using AcSELerator Analytic Assistant (limited version available free). The attached .pdf file is an example of a fault event.

 

[NorEE]

to sir Janol,

Thnx!



to sir jghrist,

the relay is in the tie feeder panel supplying the primary of the transformer through transmission lines, meaning its on the primary side. did i get you sir?

also did you mean ground=grd?

one more thing, would you kind enough to point me to a reference or if you would, explain why the relay would see phase-phase fault instead of phase-grnd.

sir, sorry for the odd questions, still a nov. but your insight is highly appreciated.

Thank you.

 

[dpc]

http://www.basler.com/downloads/transfguide.pdf

Take a look at Figure 25 for current relationships for a ground fault on wye side of delta-wye transformer.



David Castor

http://www.cvoes.com

 

[stevenal]

"Location 20.45 fault occurs 20.45km from plant A"

Not necessarily, might be miles, furlongs, or cubits. The units are whatever units the programmer had in mind when he entered the line length in the relay settings. Agree that this distance will be meaningless if the fault is beyond a transformer, since a uniform impedance per unit of length is assumed.

To see how a line to ground fault looks like a line to line fault across a delta wye, start by drawing out the phasors as depicted on the nameplate.

 

[jghrist]

the relay is in the tie feeder panel supplying the primary of the transformer through transmission lines, meaning its on the primary side. did i get you sir? [red]yes[/red]

also did you mean ground=grd? [red]yes[/red]


one more thing, would you kind enough to point me to a reference or if you would, explain why the relay would see phase-phase fault instead of phase-grnd. [red]see David's reference. The current in the secondary phase-neutral winding is coupled to the phase-phase primary winding current.[/red]

 

[NorEE]

sir jghrist and sir david,

thanks so much!

I have a follow up queastion.

The phse-phse fault happened when we energized one of our 1MVA transformers. But when we first energized with the other 3MVA transformer followed by the former (the one that caused the fault), operation resumed normal.

Whats puzzling me is the that the crew in the substation did not do anything in between the fault and the normal operation.

Q: Why is this? (There should have been some kind of action to rectify the source of fault first)


Please shed some light on this matter....

 

[jghrist]

Maybe it tripped on transformer inrush current. Your 7 Oct post said you stepped down from 13.8 kV with two 3 MVA transformers. 6 MVA t 13.8 kV is 250 A. The relay event record says it tripped with 222 A. What is the relay overcurrent setting?

 

[davidbeach]

Post the EVE or CEV file from the event.