Lloyd Price - GE Power Solutions

Imagination at work

Inspection options Turbo Generators Lloyd Price

November 2016

.

Maintenance Overview

See tutorial regarding confidentiality

disclosures. Delete if not needed.

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Generator Lifecycle Air Cooled



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Generator Lifecycle Air Cooled



Generator Maintenance Overview

Diagnostic, Monitoring and Assessment

StoppedDiagnostic Inspections

(off-line)

Rotor pulled Full Inspection



Key Areas to Address

How can I reduce the risk of a forced

generator outage?

How can I support my decision making

as to the timing of planned outages

without increasing the risk of failure?

How can I optimise my generator scope

of work during an outage ?

How can I optimise the timing and order

of my life time extension program?

Alternative Inspections





Operating on-line Monitoring

Partially opened

Diagnostic Inspection

with Rotor in Situ

(Robotic Inspection)





Operating on-line Monitoring



Generator Health Monitoring

Title or Job Number | XX Month 201X 12

L1 Sensors

Permanently installed, including cabling & connection boxes (GE or third party)

L2 GOLD® Service

• Portable DAU• Site visit twice a year• Report on collected data

Periodical Monitoring Continuous Monitoring

• Permanently installed DAU• Permanent data link &

storage• Weekly checks• Quarterly full report

L3 Service L4 Remote Service

• Permanently installed DAU• Half yearly full report



Cost-effective solution for online monitoring

L2 GOLD® Service - Generator Health Monitoring


SOFTWARE SOLUTIONS

Power Plant

Sensors• Partial Discharge

• Rotor Flux

• Rotor Shaft Voltage

On-site visit

Portable

DAU

Half yearly full report

based on collected data (snap

shot)



Data accessible at plant level with download option for analysis to GE

L3 Service - Generator Health Monitoring


SOFTWARE SOLUTIONS

Power Plant

• Partial Discharge

• Rotor Flux


• End Winding

Vibration

• Stator Temperatures

• Collector Health

Monitor*

• Stator Leakage

Monitoring System*

Server

On-site Monitoring

DCS

Half yearly full report

based on 6 months of data

USB,

CD,

DVD,

….

Sensors

Local Network

* stand alone



Data accessible at plant level with direct feed to GE

L4 Remote Service - Generator Health Monitoring


SOFTWARE SOLUTIONS

GE Monitoring & Diagnostics

• Weekly checks

• Quarterly full reports

• Permanent data storage

Power Plant

Server

On-site Monitoring

DCSSensors

Local Network

• Partial Discharge

• Rotor Flux


• End Winding

Vibration

• Stator Temperatures

• Collector Health

Monitor*

• Stator Leakage

Monitoring System*

* stand alone



Moving to condition-based maintenance

Generator Health Monitoring


Rotor Shaft

Voltage

Partial

Discharge

Rotor Flux End Winding

VibrationStator

Temperature

Leakage*Collector*

* Stand alone, check for applicability



GHM - Partial Discharge Sensors

• Capacitive Bus Couplers

• Low Frequency 9 nF sensors

• 1 Per phase + 1 at neutral point

Monitoring• Slot PD

• Void / Delamination PD

• Surface PD

• Phase to Phase PD

• Vibration sparking

• Partial Discharge location

Identification of• Stator bar insulation condition

– Aging of insulation

– Semi-conductive coating deterioration

• Loose stator bars

• Generator contamination



GHM - Rotor Flux

Sensors• Rod-Type Probe

• Wedge Mounted Flip-up Probe

• Wedge Mounted Pop-up Probe

Monitoring• Rotor Inter-turn short circuits

• Accurately identification of effected slot

• Magnitude of fault

• Trend deterioration

Identification of• Electrical breakdown of interturn insulation

• Mechanical breakdown of interturn insulation

• Carbon and Oil Contamination of windings

• Copper dusting due to excessive barring

• Turn to turn contact due to coil shorting,

distortion or elongation



GHM - Rotor Shaft Voltage

Sensors• Shaft grounding with copper braids

• Good contact even at high surface velocity

• High performance in contaminated conditions

(Oil and Dirt)

Monitoring• Electric discharge

• Shaft magnetization

• Shaft rubbing

• Grounding problems

• Brush sparking

• Rotor interturn faults

Identification of• Bearing damage

– Electro pitting

– Voltage tracking

− Electric erosion

− Frosting

• Insulation breakdown



GHM - End Winding Vibration

Sensors• HV Protected Piezo-Electric Accelerometers

− Uniaxial or Tri-axial measurement

• Biaxial Fibre Optic Accelerometers

Monitoring• Overall vibration amplitude of end winding

structure

• Vibration in relation to operating parameters.

• Trending of vibration

Identification of• End winding looseness

• Insulation fretting and contamination

• Insulation damage due to vibration

• Overhang support cracking



GHM - Stator Temperatures

Sensors• Original installed Termo Couples

• Original installed RTD’s

• Customised condition based installed

sensors

Monitoring• Stator temperatures

• Deviation from average temperature

• Temperature in relation to operating parameters

• Deviation from design parameters

• Trending of deterioration

Identification of• Blocked water cooled stator bars

• Stator cooling efficiency decrease

• Stator core defects

• H2 cooler effectiveness



GHM – Collector Health Monitor*

Sensors• Radio Frequency Current Transformers

Monitoring• Milliamp variation in excitation current

• Disruption of current flowing from the

collector brushes to the collector rings

• Trend the variation

Identification of• Sparking which is correlated to Collector

Ring Flashover

*stand alone



GHM – Stator Leakage Monitoring System*

Sensors• Optical Dissolved Oxygen Sensor

• Thermal Conductivity Hydrogen Sensor

Monitoring• Hydrogen Leakage into the Stator Cooling

Water System with high oxygen regime

• Stator Cooling Water Dissolved Oxygen

• Purges the airspace at the top of the Stator

Cooling Water Tank

• Injects oxygen to ensure the formation of

cupric oxide (CuO)

Identification of• Breakdown of the copper barrier between the

stator cooling water and the generator air

space

• Calculates the hydrogen leakage rate into the

Stator Cooling Water system

• Loss of oxygen leading to destabilization of

the protective cupric oxide (CuO) layer

*stand alone



Generator Health Monitoring Customer Training

Duration: 1 Day per Module

Generalities about generator monitoring:

Principles and constitution,Electrical power generation,PQ diagram and operating limits,GHM Generator monitoring system operation.

Module 1 - Partial Discharge Monitoring:

Functional description, Instrumentation and protections,Voids and electrical discharges,Partial discharge measurement, Data display and presentation.

Module 2 - Shaft Voltage Monitoring:

Functional description,Instrumentation and protections, Electro erosion, Sources of shaft voltages,Data display and presentation.

Module 3 - Rotor Slot Leakage Flux Monitoring:

Functional description,Operation and maintenance,Effects of rotor shorted turns,Data display and presentation.

Module 4 - Stator End-Winding Vibrations Monitoring:

Functional description,Instrumentation and signal conditioning,Issue caused by end-winding vibrations,Data display and presentation.

SOFTWARE SOLUTIONS





Partially opened

Diagnostic Inspection

with Rotor in Situ

(Robotic Inspection)



Generator In-Situ Inspections

28

Alstom –

DIRIS®GE –

MAGIC®

• Two Technologies

• Great Coverage



In-Situ (Air Gap) Inspection GE offers fast and reliable inspection of the turbogenerator without the need to pull

the rotor out. (OEM & OOEM)

1. Robotic Visual Inspection (via air gap)

2. Robotic Low Flux / EL-CID

3. Robotic Slot Wedging Tightness Test

4. HV tests (optional)

5. Brush gear & Exciter inspection

Customer benefits

Up to 40% time saving compared to

conventional inspection with rotor out

Reduced costs by keeping rotor in, simplify

crane support and lay down space

Reduced risk during overhauls due to

reduced dismantling

Accurate and reproducible assessments

Faster Return to Grid without sacrificing

safety and quality

Supports condition-based maintenance

program development

6. Partial Visual Inspection (End winding)

7. Insulation Resistance Measurement

8. Rotor Inter Turn Short Circuit Detection

(optional on Legacy GE)

9. Instrumentation check

10. Bump test (optional)

SERVICES

Several robots to fit a broad range of generator types



Flexible Robot Inspections

2016 32

Diris robot installed in sub 50MVA generator

Alstom DIRIS.mov

Alstom DIRIS.mov



Typical inspections

recommendations:

Generator in

cycled

operation or

on stand-by

on turning

gear

18-18 Retaining Rings

18-5 Retaining Rings

Every

5 Y

ears

Fro

m 9

to

12

Ye

ars

Every

3 Y

ears

Generator

in base-

load

operationCustomer benefits

Shorter down time periods due to reduced

dismantling (rotor in-situ ; end bells in place)

without sacrificing safety and quality

Increased generator availability with faster returns

to service

Accurate and reproducible assessments

Supports condition-based maintenance program

development

In-Situ Retaining Ring Inspection

GE utilizes an inspection robot to detect indications of impeding cracks

with the rotor in or out.

SERVICES



In-Situ Retaining Ring Inspection

Dec 2015 35



Flexible Robot Inspections

Dec 2015 36

Ultrasonic inspection of the retaining rings

Inside surfaces: UT (Phased Array), outside surfaces: EC (Eddy Current)

- Alstom TurboRotoscan2.mp4

- Alstom TurboRotoscan2.mp4



– Inspection Options Take aways

38

Generator Health Monitoring Generator In-Situ Inspections)


disclosures. Delete if not needed. 39

Engineering

Lloyd Price - GE Power Solutions