Protection System Scheme Testing

[DTR2011]

I am curious about how folks in the utility world view this. We are a commissioning company and prefer to test for realistic scenarios. Our test protocol (on this job) calls for very simplistic tests.

I feel like we are forced to comply with test specifications that require light bulbs and a flick on an analog meter - and the test is complete.

We have nice test equipment that can easily test a full scheme (inject fault and monitor relay, communications, breaker / reclose, etc).

Our customer seems to think that it is not necessary.

Any comments?

 

[cranky108]

We also expect our technications to do an initial scheme test to prove the wiring, relay logic, and show the cables to the breakers is in tact.

Relay tests are not enough. A whole scheme test is necessary. We also test CT's and PT's, as well as all communications paths to the remote ends.

We have from time to time done a syncronized test of protective relays at both ends of transmission lines to find timeing problems with seprate schemes.

Go the extra step. It shows up in reliability.

 

[purplepete]

In the evnet of a serious incident e.g. switchgear failure resulting in death the coroner in Australia would start by having the integrity of the switchgear investigated. Includes how it was tested. The client should be made aware of the hazards of not performing a thorough test of the whole system.

 

[ScottyUK]

From the power generation world I'd be looking for as complete a test as possible, especially on awkward stuff like transformer and generator differential schemes. Ideally a primary injection test initially, then secondary injection for each function.

Coming from an O&M background I probably have a different opinion to many EPC outfits who want the job signed off and handed over to the client while incurring the bare minimum cost and time delay. No offence intended to the good EPC guys who do the job properly.


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If we learn from our mistakes I'm getting a great education!

 

[EEIre]

Normally I would specify the following tests:

1) Functional test, including checking of all mech, key and elec interlocks

2) CT Polarity Test (Flick Test)

3) Primary Current Injection Testing (Include CT Ratio check)

4) VT Ratio check

5) Secondary Injection Testing

6) Hi voltage di-electric test (Flash Test)

7) IR / Megger Test