Control System: GE Mark V TMR
We currently have a procedure for testing the primary and emergency overspeed test on the Mark V TMR system. It was written by our controls engineer, however, he is no longer around to further pick his brain as to why he wrote it as he did. The procedure was written to perform the test OFFLINE and while the unit was OFF cool down. I will paraphrase it below since i don't have it in front of me:
<b>*** DO NOT PERFORM THIS TEST BASED SOLEY ON THE INFORMATION BELOW, IT IS SITE SPECIFIC AND IS ONLY A SUMMARY OF IT. SOME STEPS MAY BE MISSING***</b>
1. Turn off the EX2000, both the AC and DC breakers. This will trip the 86G-2 Lockout.
2. Open breakers for the follow AUX motors (Both AC and DC Lube Oil, Atomizing Air, Bearing Evac, LO Mist Eliminator, Both Cooling water pumps, Both exhaust frame blowers, Hydraulic, and maybe one more that is escaping my mind)
3. For the primary OS, Parallel 2/3 core speed sensors located on QTBA.
4. Source the frequency 3960 (Sine wave, .433 volts) and monitor the trip/speed signals (TNH, L12 something)
5. for the emergency overspeed test, parallel the three speed sensors on <P> core.
6. Force L4_XTP to "0" and Force L20FG1X to "1"
7. Test across the leads for L20FG1X Trip solenoid on the markV board to ensure the solenoid is energized.
7. Source the frequency 3960 (Sine wave, .433 volts) and monitor the trip/speed signals (TNH_OS, the L12 signal for emergency OS)
8. Test across the leads for L20FG1X trip solenoid on the markV boards to ensure the solenoid is deenergized after the trip.
I was recently asked to test the EOS (primary and emergency) while the unit was on cool down. I was unsure of this just based on it going against the procedure. Looking through the CSP to see the outcome of simulating TNH while the unit is offline for its various effects, It seems our procedure had us kill the breakers for some of the AUX motors because as TNH increases, it gives the permissive to start the motors and this was more or less for equipment protection. I looked at GE's procedure in the manual for EOS checkout, it does not aline with our procedure either but we accomplish the same result. As far as killing the EX2000, i cannot find much logic on this. I can see from the block logic diagram that the EX2000 does reference turbine speed possibly to flash the field at a certain RPM, this may be why he had the breakers turned off. The risk i see with having the unit on cool down and forcing L4_XTP to "0" and L20FG1X to "1" is that now you have the trip solenoid closed with oil pressure and the gas system NOT locked out. I understand L4 energized is required for the SRV to open and if L4_XTP is forced, L4 can never be energized. But it is GE and weirder things can happen. In the event something did internally short, or we touched the wrong wire on a terminal board, this is why, i am assuming, he wrote to have the LO and HYD motor breakers open.
To paraphrase, I am wondering if it is okay to test the Primary and Emergency Electronic Overspeed while the unit is on Cooldown? I get site conditions and versions of Mark V can be different so blanket statements are not generally advised, just looking for a little clarification if possible. Lastly, should the frequency be sourced to the Mark V using a square wave vs. sine wave at 50% duty?
We currently have a procedure for testing the primary and emergency overspeed test on the Mark V TMR system. It was written by our controls engineer, however, he is no longer around to further pick his brain as to why he wrote it as he did. The procedure was written to perform the test OFFLINE and while the unit was OFF cool down. I will paraphrase it below since i don't have it in front of me:
<b>*** DO NOT PERFORM THIS TEST BASED SOLEY ON THE INFORMATION BELOW, IT IS SITE SPECIFIC AND IS ONLY A SUMMARY OF IT. SOME STEPS MAY BE MISSING***</b>
1. Turn off the EX2000, both the AC and DC breakers. This will trip the 86G-2 Lockout.
2. Open breakers for the follow AUX motors (Both AC and DC Lube Oil, Atomizing Air, Bearing Evac, LO Mist Eliminator, Both Cooling water pumps, Both exhaust frame blowers, Hydraulic, and maybe one more that is escaping my mind)
3. For the primary OS, Parallel 2/3 core speed sensors located on QTBA.
4. Source the frequency 3960 (Sine wave, .433 volts) and monitor the trip/speed signals (TNH, L12 something)
5. for the emergency overspeed test, parallel the three speed sensors on <P> core.
6. Force L4_XTP to "0" and Force L20FG1X to "1"
7. Test across the leads for L20FG1X Trip solenoid on the markV board to ensure the solenoid is energized.
7. Source the frequency 3960 (Sine wave, .433 volts) and monitor the trip/speed signals (TNH_OS, the L12 signal for emergency OS)
8. Test across the leads for L20FG1X trip solenoid on the markV boards to ensure the solenoid is deenergized after the trip.
I was recently asked to test the EOS (primary and emergency) while the unit was on cool down. I was unsure of this just based on it going against the procedure. Looking through the CSP to see the outcome of simulating TNH while the unit is offline for its various effects, It seems our procedure had us kill the breakers for some of the AUX motors because as TNH increases, it gives the permissive to start the motors and this was more or less for equipment protection. I looked at GE's procedure in the manual for EOS checkout, it does not aline with our procedure either but we accomplish the same result. As far as killing the EX2000, i cannot find much logic on this. I can see from the block logic diagram that the EX2000 does reference turbine speed possibly to flash the field at a certain RPM, this may be why he had the breakers turned off. The risk i see with having the unit on cool down and forcing L4_XTP to "0" and L20FG1X to "1" is that now you have the trip solenoid closed with oil pressure and the gas system NOT locked out. I understand L4 energized is required for the SRV to open and if L4_XTP is forced, L4 can never be energized. But it is GE and weirder things can happen. In the event something did internally short, or we touched the wrong wire on a terminal board, this is why, i am assuming, he wrote to have the LO and HYD motor breakers open.
To paraphrase, I am wondering if it is okay to test the Primary and Emergency Electronic Overspeed while the unit is on Cooldown? I get site conditions and versions of Mark V can be different so blanket statements are not generally advised, just looking for a little clarification if possible. Lastly, should the frequency be sourced to the Mark V using a square wave vs. sine wave at 50% duty?