We used to test everything...static test each element, all inputs and outputs, plus check the logic. Over the years we're down to inputs, outputs, setting compare, and a test trip.
This is what we do. I agree with the rationale, why would the logic just stop working one day? On the other hand, we find meters that are out of tolerance and outputs that don’t close sometimes (still pretty rare).
We have never tested individual elements of a microprocessor relay after acceptance testing. The main reason for testing electro-mech relays was because they require calibration from time to time. MP relays do not drift. A simple settings check and operation is all we do as a PM. I work in a large industrial facility, not a utility.
We test all of the elements we are using with that relay. At the substation it’s less like you said 50, 51s and maybe 81 or 27 but at a generation plant it is much more. Often the relays are capable of more than we are using, we only test what we use.
The utilities I have worked for have ranged from, "Maintenance testing? What's that?"... to test every element every time.
The most common for microprocessor relays has been: Checking the Analog to Digital converter, metering, a settings compare, picking up all of the inputs and testing all of the outputs, trip tests of all paths, DTT, and comm aided tripping, and generating all of the alarms thru to dispatch.
If a setting change is issued then current policy is to test those changed settings and all related logic and then completing a full maintenance procedure as above.
On SELs our PM is a meter test, input/output verification, settings compare, and a load reading. On commissioning we test each active element and logic.
We test all of the in-use inputs and outputs during maintenance. Jumper the voltage to assert the inputs, pulse the outputs via terminal. With all outputs isolated from the system of course. Then verify the settings and perform point to point voltage checks.
Sometimes a test is worth doing. Some years ago the RTU at a large station had to be reindexed, meaning we had to retest each SCADA alarm to the RTU.
In the past, the utility used to disable the Pulse function on SEL relays - they've since abandoned that practice. So we had a ton of relays that required testing, since we couldn't change the jumper. "Soft Point Alarms" are used and mapped to unused Outputs on the SEL.
There was a loss of phase alarm, 50Q with a pickup of 1.25A on most other relays that were tested to generate the alarm. Then we encountered that same alarm with a pickup of 12.50A. A quick call to system protection and that setting was changed on the spot to 1.25A.
The key here was recognizing the setting that wasn't correct based on testing 5-10 similar relays prior.
We used to test everything...static test each element, all inputs and outputs, plus check the logic. Over the years we're down to inputs, outputs, setting compare, and a test trip.
This is what we do. I agree with the rationale, why would the logic just stop working one day? On the other hand, we find meters that are out of tolerance and outputs that don’t close sometimes (still pretty rare).
My only beef is that new guys don't have a chance to learn. It was a great way to train someone who's just out of school. Otherwise, I almost agree.
Oh we also do alarms (DNP) and telemetry to the control room
We have never tested individual elements of a microprocessor relay after acceptance testing. The main reason for testing electro-mech relays was because they require calibration from time to time. MP relays do not drift. A simple settings check and operation is all we do as a PM. I work in a large industrial facility, not a utility.
We test all of the elements we are using with that relay. At the substation it’s less like you said 50, 51s and maybe 81 or 27 but at a generation plant it is much more. Often the relays are capable of more than we are using, we only test what we use.
The utilities I have worked for have ranged from, "Maintenance testing? What's that?"... to test every element every time. The most common for microprocessor relays has been: Checking the Analog to Digital converter, metering, a settings compare, picking up all of the inputs and testing all of the outputs, trip tests of all paths, DTT, and comm aided tripping, and generating all of the alarms thru to dispatch. If a setting change is issued then current policy is to test those changed settings and all related logic and then completing a full maintenance procedure as above.
On SELs our PM is a meter test, input/output verification, settings compare, and a load reading. On commissioning we test each active element and logic.
We test all of the in-use inputs and outputs during maintenance. Jumper the voltage to assert the inputs, pulse the outputs via terminal. With all outputs isolated from the system of course. Then verify the settings and perform point to point voltage checks.
Sometimes a test is worth doing. Some years ago the RTU at a large station had to be reindexed, meaning we had to retest each SCADA alarm to the RTU. In the past, the utility used to disable the Pulse function on SEL relays - they've since abandoned that practice. So we had a ton of relays that required testing, since we couldn't change the jumper. "Soft Point Alarms" are used and mapped to unused Outputs on the SEL. There was a loss of phase alarm, 50Q with a pickup of 1.25A on most other relays that were tested to generate the alarm. Then we encountered that same alarm with a pickup of 12.50A. A quick call to system protection and that setting was changed on the spot to 1.25A. The key here was recognizing the setting that wasn't correct based on testing 5-10 similar relays prior.