6b users conference generator - frame 6 users...

June 23 – 26, 2014 | Fort Myers, FloridaJune 23 – 26, 2014 | Fort Myers, Florida

Imagination at work.

6B Users Conference

GeneratorMikkel Broas, Manager, Generator Product Service

2© 2014 General Electric Company. Proprietary Information. All Rights Reserved.

© 2014, General Electric Company.

GE Proprietary Information - The information contained in this document isGeneral Electric Company (GE) proprietary information. It is the property of GEand shall not be used, disclosed to others or reproduced without the expresswritten consent of GE, including, but without limitation, in the creation,manufacture, development, or derivation of any repairs, modifications, spareparts, or configuration changes or to obtain government or regulatory approvalto do so, if consent is given for reproduction in whole or in part, this notice andthe notice set forth on each page of this document shall appear in any suchreproduction in whole or in part. The information contained in this document mayalso be controlled by the US export control laws. Unauthorized export or re-export is prohibited.

GE Power & Water

All relative statements are with respect to GE technology unless otherwise noted.

© 2014 General Electric Company. Proprietary Information. All Rights Reserved.

Generator Maintenance

Recommendations of GEK-103566• Alternating major-minor inspections starting at 1

year and then continuing every 30 months thereafter … calendar based

Inspection Scopes• Minor

• Visual inspection of end-winding and connection rings along with various electrical tests

• Major

− Scope of Minor Inspection plus:o Field removal

o Thorough visual inspection

o Stator wedge tightness test

o Optional El-Cid

• May be substituted with a MAGIC* inspection

*Trademark of General Electric Company.


Generator maintenance


Generator maintenance

Revision of GEK 103566 in approval stage:• Release target June 2014

GEK is split into two parts• Part 1 : Calendar based maintenance outage planning

− Based on current 103566 Rev H

− Describes inspection scopes

• Part 2 : Aligning maintenance outages to prime mover

• Allows for conducting generator outages with the GT/ST outages

• Describes best methods for monitoring the unit to ensure reliability


One year inspection recommendation

Break-in period during first few initial months with possibly more severe duty/wear than normal

Provides an opportunity to repair any common manufacturing concerns such as loose hardware, dusting, foreign objects, etc.

Helps to prevent forced outage or increased maintenance outage scope

Examples of increased workscope due to not completing first year inspection


Generator Field Balancing


Generator field balancing

When is high speed balance necessary?

• New field

• Generator rotor rewind with new copper

• In-service incident causing forging or rotor damage

• Significant generator rotor modification

• Lathe work on journals

• In-service vibration concerns

• Non-standard components used

Note: High speed balance “should” include thermal sensitivity test

High speed balance is not necessary for:

• Generator rotor rewind with existing copper

• TIL 1292 repairs including profile machining and new wedges

• Routine major inspections when rotor is re-installed

• Rotor maintenance/disassembly using existing components

• Rotor maintenance/repairs approved by GE generator engineering


Generator rotor high speed balance definition

• Lathe work to ensure proper run-outs

• Mechanical balance

– Rotor body balance weights

– Other axial locations

• Thermal sensitivity test

• Bunker calibrated with actual operating data

• Overspeed test

– Set coil positions

– Proof test for forging and field components

• Flux probe test for speed sensitive shorted turns


Generator rotor High Speed Balance (HSB)

HSB will address mechanical unbalance

HSB will test for amount of thermal sensitivity

HSB will check for speed sensitive shorted turns

HSB will not fix alignment concerns

HSB will not fix turbine concerns

HSB will not fix stator concerns

HSB will not address rotor rubs due to mis-assembly

HSB will not address rotor that are assembled incorrectly or with the wrong materials


Visible Axial Motion on 6A2/6A3 Generator Fields


6A2/6A3 Visible axial field motion

Observations

• On some 6A2 and 6A3 generators, visible axial oscillations can be observed on the load gear high speed shaft (HSS)

• No equipment damage has been reported

Cause

• Cold Axial misalignment … field attempts to maintain magnetic center

• Axial force on the load gear low speed shaft (LSS) … pulls on HSS causing oscillations

Corrective actions

Perform alignment in accordance with generator mechanical outline drawing

Pay specific attention to distance between generator and load gear flanges

6b users conference generator - frame 6 users...

Documents