Did you take a look to the relay manufacturer manual?
Usually they provide some guidelines.
Please remember that you don't have to test the relay firmware but that the relay is getting the right input signals and is able to send out the right trip/alarm signals
Are you looking for actual procedures on how to set up the test eqpt or what you should be testing?
For the first, consult your test eqpt manual and the relay under test manuals. They will provide how to set up for testing.
For the second, it's basically injecting test signals that correspond to the relay set point and verifying that it trips. There is an acceptable band around the test point.
Yes, i agree. I would like to test the relay, by checking the reponse to the input , for example if i check the differential protection , i purposefully short one side of the current transformer and look if the relay trips the circuit breaker.
Electropower.
Could you please will more clear.
Are you ask about primary generator protection test?
Are you would like check this protection w/o injection test set with some manipulation on the CT/VT of runnig generator?
Regards.
Slava
For microprocessor-based and the older solid-state relays, you have the option of changing the settings "on the fly" to values that place the expected trip point within the new settings. By doing this you can see if the relay trips with real, live current and potential inputs.
If your relay installation incorporates test switches and/or test blocks, you can configure test plugs to shunt currents or disable potentials to cause relay operation. This is the way, for example, that pilot wire "end to end" tests are done. You can look at the user manuals for GE or Westinghouse pilot wire relays for a description and examples.
Shorting one CT in a differential circuit MAY work, but it also might not, depending on the the way the circuit is set up and the way the relay works.
relay testing (bench testing) and relay function testing (as you seem to wish to accomplish) are technical tasks that require a good amount of technical expertise to do well. I see a lot of cases where it's done, but not well...
I don't think you will find a procedure like this outside of turbine OEM commissioning instructions. But basically you can make your own procedure by understanding how each relay you want to test works.
For example as, you say, for generator differential relays, short one CT and increase current, until the relay trips. Load unblance, by which I take it to mean negative sequence relay (46) swap two CT leads and increase current. Over and undervoltage relays increase/decrease generator voltage until relay trips. Some relays may require test settings to prevent operating the unit in a dangerous zone (40 relay for example) Of course all trip outputs must be disabled. These tests are better done during generator open and short circuit tests.
That's what I was referring to when I said that shorting CT's may not work in a differential circuit.
For relays such as the newer microprocessor based things that take the inputs from two separate and isolated CT circuits and evaluate them numerically, shorting one CT, thereby killing one input, will result in a differential element operation.
On older electromechanical relays where the CT's are connected together in the circuit through operate and restraint coils, short in one CT of a differential pair shorts the circuit out and no operation results.
That's why it is essential that the engineer or technician understand how the particular equipment operates, instead of taking a "cookbook" approach.
I've been called in to troubleshoot problems with relaying that was directly traceable to poor test techniques. Fortunately the company that did the original testing was not able to fix the problem, and I worked for a different company...
electpower - I'll suggest you find someone who does testing for a living and watch them do it. If you say the system is ok and its not because you did not understand what had to be done in order to correctly test the system under evaluation you're probably in trouble. If you try to test the system without understanding the adjacent causes and effects you might cause an outage to something else.....this is why the testing and commissioning people get the big bucks!
I made mediocre bucks... Do you have a lead on the 'big bucks'?
Right now one of my former co-workers and good friends is getting his feet on the ground at a new employer's facility. He's found a good amount (a SCARY amount) of protection disabled because it was giving erroneous trips. Nobody on the staff knew how to troubleshoot it nor did they have a real idea of what it was supposed to do anyway, so they just disconnected it from the trip circuit and made it an alarm.
I responded to a call at a facility where a fault had cleared by blowing the fuses on the incoming ustility feed outside the fence. Since inside the fence was a line-up of 13.8 switchgear that should have tripped before the fuses blew, I was interested in what went wrong. I found the instantaneous overcurrent elements had flagged on the electromechanical relays (Westinghouse CO's) but the breakers had NOT tripped. A minute later I found the battery charger had been de-energized and disconnected from the station battery bank, and that had been the situation for years. Nobody in the (state-run) facility had the foggiest idea of how the switchgear worked or what the battery bank was supposed to do. All they knew was that things ran just fine without the batteries. And it did, until that fault downstream. They'd been closing breakers with the manual maintenance bar, and tripping them using the manual trip on the front of the breaker. Again, incomplete knowledge of the system that went un-detected for years, because the facility staff did not even know which questions needed to be asked until somebody showed up that was familiar with the equipment and how it was supposed to work...
These are but a couple of examples of problems that can arrise from incomplete knowledge, so be careful. If you have the slightest doubt, talk with others.
Old Field Guy.Great!!!!
You are right!!!!
Agree with each your word and I think all others commissioning guys too.
"big bucks" what is this??? How much??? 100$ or 100k$.
"big bucks" we pay not for work, for knowledge of the system, for responsible, for warranty. you need calculated how it's save: unwanted trips, no trips, damages, etc..
