Good morning,
During a recent major outage, we replaced and rewired three primary and three emergency overspeed probes. We had high vibration during startup (another issue altogether) and had one of the emergency overspeed probe wires come loose, producing a 0 signal in the prevote logic. After a few months of running in this manner, with plans to remove the bearing cap and rewire the faulted sensor during the next outage, we had a 2nd emergency overspeed probe wire come loose, and now have a diagnostic alarm L14H_ZE. A little research shows this alarm appears to be active when 2/3 emergency overspeed probes indicate a 0 instead of a 1. Here is my question. What is the result of a loss of the third emergency overspeed probe? Is it a trip, or are we already in a position where a trip will not occur if called for due to 2/3 overspeed probes indicating a 0 logic? Calling CSA on this one, I'm sure he'll be able to steer me in the right direction.
Thanks in advance,
Bill
During a recent major outage, we replaced and rewired three primary and three emergency overspeed probes. We had high vibration during startup (another issue altogether) and had one of the emergency overspeed probe wires come loose, producing a 0 signal in the prevote logic. After a few months of running in this manner, with plans to remove the bearing cap and rewire the faulted sensor during the next outage, we had a 2nd emergency overspeed probe wire come loose, and now have a diagnostic alarm L14H_ZE. A little research shows this alarm appears to be active when 2/3 emergency overspeed probes indicate a 0 instead of a 1. Here is my question. What is the result of a loss of the third emergency overspeed probe? Is it a trip, or are we already in a position where a trip will not occur if called for due to 2/3 overspeed probes indicating a 0 logic? Calling CSA on this one, I'm sure he'll be able to steer me in the right direction.
Thanks in advance,
Bill