The Generator Condition Monitor Explosion Proof Design The GCM-X
Outline Role of generator monitoring The GCM system (history, operation, benefits, installation, commissioning) Collector analysis Alarm reactions
Generator Monitoring Examples Condition Detector Arcing Shaft/rotor imbalance Stator insulation deterioration Moisture Hydrogen purity Electrical overload Radio frequency monitor Vibration sensor Partial discharge analyzer Dew point analyzers Thermal-conductivity analyzer Protective relays
Generator Monitoring Examples Condition Detector End-turn vibration Rotor winding shorts Excessive temperature EXPERT systems Overheating/arcing Fiber optic accelerometer Air-gap search coil (magnetic fields) RTD s, thermocouples GEMS Generator Condition Monitor (GCM)
Detection of Overheating/Arcing Review of Applicable Devices Device Overheating Arcing Temperature Sensor YES, Not Early NO (RTD, Thermocouple) Radio Frequency Monitor NO YES Partial Discharge Analyzer NO YES Generator Condition Monitor YES, Very Early YES
Generator Condition Monitor Brief History 1968 Developed at GE by G. Skala, et al 1971 Environment One builds first 10 for GE 1974 Detection at Detroit Edison 1975 GE designs own version 1975 Environment One obtains patent license
First-Generation Generator Condition Monitor
Single-Cabinet Generator Condition Monitor (ATEX II prohibits use in Europe in 2006)
Auto Alarm Remote Panel The Auto Alarm was added to the GCM system to distinguish between low-flow conditions, electronic faults and actual verified alarms from overheating or arcing.
Split Cabinet Generator Condition Monitor (ATEX II prohibits European use in 2006)
Explosion-proof Generator Condition Monitor (Earlier Cenelec configuration is prohibited for European use in 2006; ATEX II directive)
The GCM System Detector assembly Sensor Sampling system Electronics Automatic alarm verification Self-diagnostics Flow control
The GCM System Oil/moisture trap Gen-Tags Collector analysis
GCM Piping
GCM Principle of Operation Ion chamber detector Detection of submicron particles
GCM-X Ion Chamber Detector
Thermal Particulation Temperatures Turbine Lube Oil Mica-glass Laminate Silicone Rubber Glass Epoxy Laminate Polyphenolic Varnish Melamine Teflon Gen-Tags 125 130 C 200 C 200 C 250 C 260 C 350 C 440 C 200 C
Clean Hydrogen When there are no particles from overheating present, ion chamber output is 80% nominal.
Hydrogen with Thermal Particulation When overheat particles are present, they are attracted to the collector and reduce ion chamber output.
GCM Piping
Thermal Degradation Not subtle Dramatic signal Facilitated in generator environment Easy to detect One source thermal Minimal interference Minimal mass very early warning
GCM-X Front Door
GCM-X Display/Control Panel
GCM-X (ATEX) with Door Open Location of: Processor PCB I/O PCB Flowset transmitter Flowset valve Sample collector Sample flowmeter
GCM-X (ATEX) Rear View Location of: Ion chamber detector Filter/solenoid assembly Sample solenoid ICD heater
Benefits Early warning Reliable Proven Broad range of detection Stable minimal interference Simple Cost-effective Low maintenance
GCM Installation Determine location Minimize potential for contamination Avoid flow changes Maximum 100 ft (30 m) inlet High-pressure/low-pressure taps Vent connection Wiring connections
Oil/Moisture Trap The Oil Moisture Trap is used to protect the GCMX from oil and liquid contamination.
GCM-X Located on Turbine Floor
GCM-X Location under Generator Belly
GCM Commissioning Generator operating mid-point Adjust flow through GCM Calibrate Confirm status w/ filter Initiate sampler/confirm flow Confirm wiring to control room
Alarm Reaction Considerations Generator characteristics Design Age Performance/experience History with GCM Severity of alarm Recent maintenance/modifications
Alarm Reaction Fact Something is abnormal (overheating or arcing) Action Insure alarm sample was collected Send sample for analysis Note generator operating condition Review other monitors Continue? Deload? Shut down?
Collector Analysis Collector analysis is used to validate a GCM alarm and to analyze the pyrolysate products that are generated during the thermal even it becomes even easier if you have Gen- Tags Operators can maximize the benefits of the GCM and GCM-X system by maintaining a regular collector analysis program which can help identify shifts in the generator s baseline condition
Collector Analysis Confirms validity of GCM alarm Qualifies nature and/or source of the alarm Provides historical data baseline for comparison Standard analysis process or emergency 24-hour turnaround Conventional or Gen-Tag analysis
GCM Saves Customer Pacificorp Glenrock, WY ABB Baden, Switzerland Canal Electric Sandwich, MA Details GCM detected a field ground approximately 42 minutes before the generator was manually tripped. The alarm was the result of several rotor end windings elongating and shorting to the retaining ring. GCM used during field test of generators detected a stator cooling water blockage early and prevented further damage. Before using the GCM routinely, ABB lost an entire rotor, which they felt could have been prevented if a GCM was installed. GCM detected a hot spot approximately two square inches in size.
GCM Saves Customer Ontario Hydro Nanticoke, Ontario CP&L Roxboro, NC Pacific Power Centralia, WA Details GCM alarmed over 30 minutes before failure of generator. Warnings were given months before as the GCM was alarming sporadically due to back core burning. GCM alarm prompted a manual trip of the generator. Tests later uncovered two shorted stator coils. GCM detected overheating in a 655 megawatt generator while it was ramping up to full load without the hydrogen coolers operating. The GCM alarmed when the generator reached 150 megawatts and approximately 30 minutes before being manually tripped at 254 megawatts.
GCM Saves Customer ACEC Charleroi, Belgium Virginia Electric Mount Storm, WV National Power Eggborough, UK Details GCM detected overheating within a generator during commissioning of unit, caused by shipping baffles that had not been removed before start-up. GCM was alarming intermittently when generator was at high loads. Transposition test revealed high resistance between several tube to copper resistors. One faulty resistor resulted in a hole being burned in the cooling duct where it had been soldered. GCM detected a stator cooling water blockage and the generator was tripped, thereby preventing further damage.
ATEX directive 99/92/EC E/One is interested in working with European utilities and independent power producers as they plan their compliance strategy in advance of 2006. Options exist, ranging from field upgrades to ATEX compliance to full replacement of older designs with current versions that are fully compliant with the directive. If your plant has a GCM Single Cabinet, GCM Split cabinet, or GCM-X (Cenelec) configuration, contact E/One to determine the available options. E/One requires a unit serial number reference to answer how your site can comply with the directive.
GGA/GCM-X Gas Station Ideal for retrofit applications a cost effective option combining gas purity and overheat monitoring.
Questions & Answers
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