We have 2 6B machines with MARKV <I> controls. We are getting a Diagnostic alarm on each core.
T2 1 R 1741 TCE1 Ground Fault on P24AS/N24AS Bus
T2 1 S 1741 TCE1 Ground Fault on P24AS/N24AS Bus
T2 1 T 1741 TCE1 Ground Fault on P24AS/N24AS Bus
I view these on DIAGC and each positive and negative 24 volts are low.
I go to the HELP_QD.dat and it steers me to the TCEA board. Each core has a TCPS board that supplies this 24 volts to the core.
Question: I have my doubts that each cores TCPS board has failed. Does <P>'s TCEA board monitor each cores 24volt?
Is this happening on BOTH units?
After a maintenance outage on both units?
I don't have access to any Speedtronic manuals at the writing. But, you do. Appendix D of the Mark V Application Manual, GEH-6195, shows what card has what power supplies.
my guess is something powered by the 24 VDC power supplies of the TCEA is grounded. I believe if you look at the <P> PTBA (I think it's the PTBA) you will see that the 24 VDC comes from each TCEA, through the TCEB, and to the PTBA. The three 24 VDC power supplies were high-selected through a diode selector on the TCEB before being passed to the PTBA.
I believe in later versions of the Mark V that the Reuter-Stokes Flame Trakker interface modules were, at least in part, powered by the <P> 24 VDC power supplies. SO, if one device powered by the <P> 24 VDC power supplies develops a ground, they may all, effectively, be grounded.
Please write back to let us know what you discover.
Happening on only one unit. I suspected the flame detector scheme originally but got side tracked with the 3 cores having grounds. Thanks for the redirection.
I will go through all your suggestions and follow up with what I have found.