|
|
Enron Mail |
There are several ambiguities and operational issues with this definition.
SOT: First, the phrase "available to operate without a status condition or fault that would otherwise limit its operation" in SOT is very easily misunderstood. Many owners & I.E.'s think that "System Okay" means the turbine should produce power, as per the power curve, during every second of SOT. This isn't true. If the turbine is paused offline or manually stopped, untwisting cables, resetting, undergoing a load shutdown, in low noise operation, or in spinning or starting up mode, then the SOT clock is incremented even though the turbine can't produce power. I think the SOT description should read something like"not faulted off for turbine malfunction or offline for failed turbine systems." Either that or call this counter something other than "System Okay". DT: The phrase "or that is counted as Weather Out Time" may confuse the owner. According to SCADA training if a downtime fault occurs at the same time as a "weather out" condition then the turbine fault (DT) will have precedence. This precedence may be hard to explain to owner. Therefore, I recommend you delete the Weather out phrase. In other words, stop the sentance on Majeure Events. LOT: Precedence also can cause confusion here. If a turbine fault occurs when the grid is outside of specs we've been told that DT will always take precedence whether the grid induced the fault or the fault occurred due to turbine malfunction not related to the grid. How does the controller distinguish (and analysts from ten minute SCADA data) whether the fault was due to the grid or the grid was driven out of spec by a turbine malfunction? I recommend that you replace the phrase "except where line conditions are forced out of specs due to Turbine malfunction" with " except when the turbine faults offline." Further, it should be noted that when the turbine faults off due to grid variations then it probably is true that EWC is penalized for the grid variations. MT: How do we implement the 36 hour limit on MT in the equation? I assume that we compute a value MTexcess that is that portion of MT in excess of the 36 hour limit. Then we use MTexcess in the numerator instead of MT to penalize EWC for exceeding the MT limit. Where did 36 hours come from? The previous limit in all existing 1.5 contracts is 48 hours and MT, as defined by the controller fault listing, includes several other tasks that are not on a scheduled maintenance checklist. The 48 hours per year was intended only to capture those tasks on the maintenance checklist. WOT: How does the controller know when the turbine can't be repaired due to weather related events or that weather makes access unsafe? If it can't then you are adding an activity that must be tracked by manual log and integrated into availability computations by a manual procudure that is not value added to the customer and costly to operator. EOT: What about icing sensor shutting down turbine? This isn't due to Owner. ST: This definition of ST rarely equals the total number of hours in the "survey or measurement" period due to communication losses and power outages. I recommend you remove that phrase from the definition OR alter the definition of availability to (SURVEY - DT - RT - MT)/(SURVEY - MTprorated). SURVEY is the maximum possible number of hours in the survey period and MTprorated is the percent of 36 hours per year in the survey period. I recommend keeping the current availability definition as it uses info already in Visupro. Availability equation as shown doesn't penalize EWC for MT above the 36 hour limit. See MT above for solution. From: Ilan Caplan on 04/17/2002 09:14 AM To: Mark Fisher/EWC/Enron@Enron, Mark V Walker/EWC/Enron@ENRON cc: Hollis Kimbrough/EWC/Enron@ENRON Subject: Proposed Clipper Availability Mark(s) - Please review the attached calculation which Clipper proposes for Availability. I will compare it with the contractual availability which have recently proposed, but would prefer your input. Thanks, Ilan ---------------------- Forwarded by Ilan Caplan/EWC/Enron on 04/17/2002 09:26 AM --------------------------- Mark Eilers 04/17/2002 09:02 AM To: Ilan Caplan/EWC/Enron@Enron cc: Subject: Availability Ilan Can you please give this a quick read to see if this my work. This is a take on our standard availability that Clipper is proposing. Let me know your thoughts. Mark
|