Bus bar protection commissioning

[ballenden]

Hi,

I have had experience in testing busbar protection via secondary injection methods. This is easier because no live circuitry involved, no HV switching required.

Can anyone give me tips on how to carry out site-commissioning, especially with regard to adding new bays to bus protection to existing substation?

I would think that secondary injection is still an option, to prove zone stability. Then, I/O check to confirm switch statuses. I also have the option to switch bus protection to OFF, to do online stability checks.

Could you also refer me to a document for reference?

Please help.

Ciao.

 

[DiscoP]

Don't know about documents, but we would test the relay calibration using secondary injection, but for commissioning we also do a primary balance to check all the wiring. We also temporarily cross the phases at the test links to see sqrt(3)× current in the cross phases.
Secondary tests will check the relay, but a relay is only one part of the scheme.

 

[veritas]

Hi Ballenden

Yes, I would strongly recommend primary injection tests as well. Depending on what kind of relay you are using (hi or low impedance) and its settings you will need about a few hundred amps injection set.

This is the only way to properly prove CT polarities and ratio. Also, it will prove the minimum current required to operate your diff protection system.

I am not aware of any docs on bz testing. I just write my own procedured/test plans and most of my customers do not know of any better.

Hope this helps.

 

[alehman]

Primary also should be used to prove any interlocks or auxiliary relays that might exist.

 

[slavag]

Hi.
From my point of view, primary test is MUST.
Isn;t simple, aspecially in the exsiting substation, many times request disconnect allo customers.

Additional option , primiry test with load current, but it's depend on the relay type.
Best Regards.
Slava

 

[ballenden]

Thanks so far,

I have a low-impedance scheme to commission. Problem is that customer does not want to disconnect loads.

Double busbars are available, so we would probably create a dead bus then we could test CT ratio & polarities via primary injection. But I have a problem wrt the added bus coupler. Two CT's will be used on either side of the coupler circuit breaker,creating zone overlap.

How would I test stability of the zone across the coupler that is created with the live circuits?

Appreciated.

 

[veritas]

Hi Ballenden

Are we talking about an indoor or outdoor installation here? What voltage level for interest sake?

Thanks.

 

[ballenden]

Hi veritas,

It is outdoor installation at 132kV.

thanks.

 

[WhiteyWhitey]

I have done commissioning tests before with primary injection over a 33kV Circuit breaker. The CTs were integrated into the Breaker.

If you have a ring set up and isolators between the coupler and the bus then you could isolate the bus coupler under test from the isolator.

We used to do breaker testing before connecting the flexible busbars to the busbar and then use the busbar outage to do the final connections.

I dont know its hard to say without a Single line diagram and an idea of the equipment for me.

Cheers,
Andrew

 

[stevenal]

I'll vote for on-line testing. I suppose primary injection could be used if you can isolate two bays at a time. Switching is still required. Secondary injection could be used to prove the relay will trip. When trying to prove stability, though, you are bypassing the CTs which could have been wired cross phase, wrong polarity, or wrong ratio.

 

[slavag]

Hi Ballenden.
Need SLD and relay type.
Are possible disconnect BBP from trips only and add some small load on the new part-one bay only?
1. You check all new part with primary test, on-load test are recommended with some DG, include coupler and couplers CT's with simulation of closed position of disconnector to the live/exost part.
2. Disconnect trips from BBP
3. Connect voltage to new part and will feeded some load on the one of the bays.
Best Regards.
Slava