Joe,
Lets not forget that we had measure problems due to failing MS3 relay in the 
SEG converter, which caused the crow bar to engage, which in turn forced CB1 
to fault.

CB1 is designed to do both synchronization and was set to protect the turbine 
and the converter in a fault condition. The original instantaneous settings 
of 8000A was too high and allowed too much current through the system that 
damaged the converter and caused IGBTs to blow before it tripped. The second 
failure was due to a QA issue with failing CB1 to trip when it was commanded 
to by the converter. In both events we had catastrophic failures and lost 2 
converters due to CB1 failing to protect the system. To remedy this problem, 
we installed the PMT for CB1 redundancy and decreased the instantaneous 
setting from 8000A to 3000A and since then we didn't have any IGBT blow ups 
or any catastrophic failures

Even though that I am still not clear about Gary's question at the end, I 
hope that the above provide some help.


Thank you,

Tim M  




Joe Thorpe
06/13/2002 04:48 PM
To: Kurt Anderson/EWC/Enron@ENRON, Kevin Cousineau/EWC/Enron@ENRON, Tim 
Mohammed/EWC/Enron@Enron
cc: Jeff Maurer/EWC/Enron@ENRON, John Nemila/EWC/Enron@ENRON, Hollis 
Kimbrough/EWC/Enron@ENRON, Mark Fisher/EWC/Enron@Enron, Mark V 
Walker/EWC/Enron@ENRON 

Subject: Zilkha Availability

Kurt,
 Per our phone conversation, Mark Fisher and myself have been discussing 
availability with Gary from Zilkha. A question arose regarding the many 
operations of our breaker in the pad mounted transformer that took place 
December through March. Gary's thought is that when we recalculate the 
availability, we need to count these times as down time and not Line Out 
Hours as they have currently been counted. I suggested that according to 
Exhibit GG in the TSIA, LOH is defined in short as any time the grid does not 
meet "(i) the specifications required by the WTG as set forth in the 
Technical Specifications", and Gary agrees with this. The problem is that an 
engineering change on the breaker settings was implemented some time in March 
to reduce the number of breaker operations on site. We are still seeing many 
grid faults in the turbine but not in the PMT breaker. The question that Gary 
brought up is were the original settings of the breaker set to the WTG 
Technical Specifications and operating due to the on going grid conditions OR 
were the settings improper to start with causing the breaker to operate while 
the grid was within Technical Specifications.