Commissioning test for Generator relay

[jhonsom]

The relay has following funtions: distance, v/hz, synch check, auto synchronism, undervotlage, reverse/forward power, loss of field, negative sequence, overcurrent, time over current, over voltage, stator ground fault, out of step, frequency relay, current/ground differntial.

Should we write in literature/ manual of the relay how to perform commissioning test for all the functions. Does any body test these funtions in the field? what are the critical commistion test for the relay?

 

[rbulsara]

Relays are tested using a relay test set. Most qualified (NETA certified in the USA) electrical testing companies would have the requisite equipment and expertize.

The test procedures are usually provided by the relay manufacturers or in a manual, but not all them are straight forward. A good test technician would know.

Yes, any good engineer/owner would test (or get tested) the relay functionality, preferably at the proposed settings.

The relay test set however does not test wiring external to the relay but that is not part of a relay test.







Rafiq Bulsara

http://www.srengineersct.com

 

[esee135]

In general, relay testing involves secondary injections controlled through a 3 phase test set. The idea is to simulate operational modes to basically trace the expected operational curves using automated sweeps of 3 phase voltages and currents. This is assuming that the metering circuits of the relay have been tested to verify correct calibration.

For example, verifying time/magnitude inverse time curves.

 

[oldfieldguy]

In addition to the tests of the protective functions of modern digital relays, you need to add checks that validate programming of protective functions.

It is more than a little upsetting to have a protective element that functions perfectly but is not properly programmed to have the element actually operate an output.

Sadly, the versatility of microprocessor-based and very flexible protective relaying has outpaced the competence of a lot of people who were quite competent in the application of the older protective devices.

old field guy

 

[esee135]

I agree with 'oldfieldguy'. The final 'trip' test is still required to fire the 86's and 94's and breaker trips/flags/annunciation, even in the digital world.

Kudos to 'oldfieldguy'. The electromechanical relays well applied will still protect you. It is far too easy to turn on every protective function in a multi-function relay thinking you are making a better protection scheme.

Unfortunately with relay testing, the relay test is only as good as the individual who comes up with the test plan.

 

[powerjunx]

jhonsom, you're talking about protective relaying schemes for power generators.
Upon testing relay, take note, settings were referred to generator characteristics, results of load flow simulation and short circuit calculation without these results proper tripping coordination may not achieved especially when your system involves with import and export of power from power grids.


"..the more, the merrier" Genghis Khan