CSA. I will try after a long time of absence to be more specific.
Usually when the unit is stopped we have a purity of 97%. When the machine accelerates to FSNL and then synchronizes we have a steady drop that finally drives purity to 95%. While the machine is running for 1 month continuously we see a drop until 92@. If we increase the low flow scavenging then we will drive the purity back to 97%.
we dont wait to let the automatic scavenging start, we interfere before with the low flow scavenging.
Sensors of purity analyzer measure for 55 minutes the purity pon the two ends and for 5 minutes they measure the casing. The numbers i give is from the lowest purity part the Generator TE. Casing is higher. BUT the drop is more or less the same in all measurements.
In the worst case, when we start eh manual low flow scavenging we have TE 92%, CE94% Casing 96%.
The main seal oil flow is staedy through the 2,5 years of plant commercial opeartion.
The hydrogen is 99,99999 purity.
Unfortunately we dont have individual seal oil flow rates.
The seal oil flow rate is the same before and after the MAGIC inspection.
The unit does not have hydrogen dyer and the seal oil is nto vacuum trated.
We had an issue with the coolers , a suspicion of leakage.
That is all i can say for the moment.
Something last , the problem started form the time that we changed the moisture indicatiors of the purity analyzer. I dont know and i dont think that this has anything to do with the purity drop but in any case i have to mention it.