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Enron Mail |
To cut to the chase....would CB1 fault the turbine when the PMT breaker
tripped and if so then would the downtime or line out time availability hour counter be incremented? If the PMT breaker trip doesn't always cause a given fault then is there any easy way (SCADA data or site crew experience) for us to estimate what percentage of the trips did fault the turbine offlline due to a downtime or line out fault? Please answer these questions; we will then know what corrections, if any, we need to make to availability. Tim Mohammed 06/14/2002 07:52 AM To: Joe Thorpe/EWC/Enron@Enron cc: Kurt Anderson/EWC/Enron@ENRON, Kevin Cousineau/EWC/Enron@ENRON, 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, Tom Nemila/EWC/Enron@ENRON Subject: Zilkha Availability 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.
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