ENERGY SERVICES ENGINEERING PRODUCT SERVICE
TIL 1420-2R1 30 OCTOBER 2007 Compliance Category – M Timing Code - 7
TECHNICAL INFORMATION LETTER LUBE OIL LOGIC ENHANCEMENT APPLICATION All Gas Turbines equipped with Speedtronic Control Mark V or Mark VI.
PURPOSE To change the Speedtronic Control Panel to protect the turbine bearings following a plant AC power loss by maintaining the continued operation of the DC lube oil pump.
REASON FOR REVISION Update to include Frame 5, Frame 6 and Frame 9 turbines. Compliance Category O - Optional
Identifies changes that may be beneficial to some, but not necessarily all, operators. Accomplishment is at customer's discretion.
M - Maintenance
Identifies maintenance guidelines or best practices for reliable equipment operation.
C - Compliance Required
Identifies the need for action to correct a condition that, if left uncorrected, may result in reduced equipment reliability or efficiency. Compliance may be required within a specific operating time.
A - Alert
Failure to comply with the TIL could result in equipment damage or facility damage. Compliance is mandated within a specific operating time.
S – Safety
Failure to comply with this TIL could result in personal injury. Compliance is mandated within a specific operating time.
Timing Code 1
Prior to Unit Startup / Prior to Continued Operation (forced outage condition)
2
At First Opportunity (next shutdown)
3
Prior to Operation of Affected System
4
At First Exposure of Component
5
At Scheduled Component Part Repair or Replacement
6
Next Scheduled Outage
7
Optional
COPYRIGHT 2007 GE The information published in this Technical Information Letter is offered to you by GE in consideration of its ongoing sales and service relationship with your organization. However, since the operation of your plant involves many factors not within our knowledge, and since operation of the plant is in your control and ultimate responsibility for its continuing successful operation rests with you, GE specifically disclaims any responsibility for liability based on claims for damage of any type, i.e. direct, consequential or special that may be alleged to have been incurred as result of applying this information regardless of whether it is claimed that GE is strictly liable, in breach of contract, in breach of warranty, negligent, or is in other respects responsible for any alleged injury or damage sustained by your organization as a result of applying this information. This Technical Information Letter contains proprietary information of the General Electric Company, USA and is furnished to its customer solely to assist that customer in the installation, testing, operation and/or maintenance of the equipment described. This document shall not be reproduced in whole or in part nor shall its contents be disclosed to any third party without the written approval of GE Energy Services Engineering.
TIL 1420-2R1
BACKGROUND DISCUSSION The emergency DC lube oil pump operates in the event of a loss of AC power supply to the electrically operated lube oil main pumps or failure of the main mechanical lube oil pump. This causes a loss of lube oil pressure, and initiates the emergency DC lube oil pump operation. The operation of the emergency DC lube oil pump is also controlled by the speed feedback signal from the speed pickups. Upon zero speed detection the DC pump is stopped due to a perceived turbine shaft standstill condition. However, an event was reported in which the loss of speed signal caused the DC lube oil pump to stop its operation while the turbine shaft was still rotating. This caused extensive damage to the bearings.
To implement the enhanced control logic for the lube oil system, if applicable, please contact your local GE Service Manager or Contract Performance Manager (CPM). This updated logic extends operation of the DC lube oil pumps for 30 minutes following a turbine trip due to loss of power to the AC pump motor or the loss of oil pressure from the main lube oil pumps. Implementation of the new logic will ensure that even if the speed pickup signal is lost, the DC pumps will maintain adequate lube oil flow to the bearings for unit coast down. Units shipped after 2003 have already implemented the latest control software and are not affected by this TIL.
PLANNING INFORMATION Compliance • Compliance Category: M • Timing Code: 7 Manpower Skills A qualified GE Controls TA. Parts None. Special Tooling None. Reference Documents None.
Figure 1:
Damaged Bearing
GE has developed new control software to enhance the operation of the DC lube oil pump. The new control software extends the operation of the DC lube oil pump by 30 minutes following a turbine trip due to loss of AC power or loss of lube oil pressure. This enhancement ensures that even if the speed pickup signal is lost, the DC pump will maintain adequate lube oil flow though the bearings until the unit is safely brought down to zero speed. The 30 minutes is an estimated maximum time required to decelerate the unit from rated speed to zero speed. In addition, the new logic measures all bearing temperatures and selects the maximum value. The previous logic measured the temperature at bearing #2 only.
RECOMMENDATIONS GE recommends that a qualified GE Controls TA review the existing control sequence at the first opportunity, to determine if these software upgrades are applicable.
Previous Modifications None. Scope of Work GE Controls TA to perform on-site checks to determine if a software change is required. If software changes are required a second trip to site will be required after the software has been updated, for its installation and testing. Estimated time: Controls TA - four hours for each operation. Two hours craft labor required for post-upgrade testing. To implement the upgrade, as-running software should be submitted to GE engineering by Service Manager or CPM two weeks prior to the required implementation date. After approximately two weeks the upgraded software will be returned to the site for implementation by a qualified GE Controls TA. Contact your local GE Service Manager or Contract Performance Manager for assistance or for additional information. NOTE: If you would like to receive future TILs by email,
contact your local GE Service Manager or Contract Performance Manager for assistance.
COPYRIGHT 2007 GE This Technical Information Letter contains proprietary information of the General Electric Company, USA and is furnished to its customer solely to assist that customer in the installation, testing, operation and/or maintenance of the equipment described. This document shall not be reproduced in whole or in part nor shall its contents be disclosed to any third party without the written approval of GE Energy Services Engineering. Page 2 of 4
TIL 1420-2R1
TIL COMPLIANCE RECORD Compliance with this TIL must be entered in local records. GE requests that the customer notify GE upon compliance of this TIL. Complete the following TIL Compliance Record and FAX it to: TIL Compliance FAX: (678) 844-3451 Toll free FAX: 1-888-896-TILS (1-888-896-8457)
TIL COMPLIANCE RECORD Site Name: Customer Contact Information
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COPYRIGHT 2007 GE This Technical Information Letter contains proprietary information of the General Electric Company, USA and is furnished to its customer solely to assist that customer in the installation, testing, operation and/or maintenance of the equipment described. This document shall not be reproduced in whole or in part nor shall its contents be disclosed to any third party without the written approval of GE Energy Services Engineering. Page 3 of 4
TIL 1420-2R1
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COPYRIGHT 2007 GE This Technical Information Letter contains proprietary information of the General Electric Company, USA and is furnished to its customer solely to assist that customer in the installation, testing, operation and/or maintenance of the equipment described. This document shall not be reproduced in whole or in part nor shall its contents be disclosed to any third party without the written approval of GE Energy Services Engineering. Page 4 of 4
