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Shorted Turn Detection for Generator and Motor Rotors

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Site www.Generatortech.com 

See our article in Power

Engineering Magazine 

Flux Probes Provide On-Line

Detection of Generator

Shorted Turns 

"The use of air-gap magnetic

flux probes has proven

effective in the detection of 

generator rotor winding

shorted turns and has helped

to improve the quality of 

predictive maintenance

decisions concerning when

or if to perform rotor

rework..." PowerEngineering September

1999, Volume 103, Issue 9, p.

28-32 

Generatortech, Inc.specializes in the detection of rotor winding shorted-turns in synchronousgenerators and motors. This information can help your plant operators andengineers pinpoint the cause of abnormal vibration, assist in major maintenancedecisions and verify the quality of rewound rotors. These pages provide

information on the theory behind the field winding shorted-turn detection systemfor round rotor generators. We utilize a similar technique to detect shorted-turnsin synchronous salient pole motors and generators.

Generatortech, Inc., as the industry leader in shorted-turn detection and analysisservices, offers:

  permanent and temporary air-gap flux probes designed for your machines  installations of permanent and temporary flux probes  testing services

o  tests and report provided by our staff

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o  testing conducted by your own staff using rented Generatortechequipment, but data analyzed and report provided by Generatortechexperts.

  Rotor Winding Shorted-Turn Analysis Package. Will allow your staff to testand analyze your machines.

Data collected on a 2-pole, 7-coil/pole generator with 1 out of 9 turns shortedin Pole A - Coil # 3.

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Overlay of Pole A and Pole B's coil #3 lead slot peaks from data aboveshowing the decrease in slot leakage flux due to shorted turn in Pole A - Coil #

3.

Valuable Predictive Maintenance Tool

Shorted turns are the result of failed insulation between individual windings ingenerator rotors and can cause:

  Load sensitive vibration  Undetected local winding hot spots  Excessive excitation currents  Possible forced outages

In today's highly competitive electrical power market, predictive maintenance isan effective method of minimizing maintenance costs and downtime. Monitoringthe condition of your rotor windings using the Generatortech, Inc. flux probe andanalysis products will help you make informed decisions on "when" and "if" tobring a machine down for a major overhaul and rotor rewinds.

Versatility and Quality

Generatortech, Inc. can install probes in all major power generation equipment,including Gas, Steam, Hydro, Fossil and Nuclear. Quality design, construction andinstallation are top priorities at Generatortech.

Generatortech. Inc.'s computer analysis program records and analyzes flux probedata, yielding a highly accurate "snapshot" of the rotor winding insulationcondition. Our system not only tells you if you have shorted turns in the rotorwinding, but it pinpoints which coils are affected and provides an accurateestimate of the number of turn shorts in each coil. We currently have about 400 ofour air-gap flux probes in generators worldwide. With this many probes in place,we have been able to confirm the accuracy of our analysis system many times.When rotors with shorted turn indications have been inspected during rotorrewinds or retaining ring replacements, we have found excellent agreement withour on-line shorted turn indications.

Generatortech, Inc. performs full service installation, testing and analysis withreporting and trend analysis. Although moderately complex, Generatortech, Inc.can train power plant personnel to perform installations, testing and analysis ontheir own. Some plant operators choose to take their own test data and have theanalysis performed by Generatortech, Inc. Generatortech, Inc. recommendsbaseline testing of new or rewound rotors and a continuing program of periodictesting for predictive maintenance evaluations.

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Air-Gap Flux Probe Technology forDetecting Rotor Winding Shorted Turns

Generatortech specializes in detecting rotor winding shorted turns in round rotor and salient

pole generators and motors while your generator is online and at speed and temperature .

We have over 20 years of dedicated experience in the science of rotor winding shorted turn

detection, and a worldwide customer list including most major OEMs, generator service

companies and power utilities. Generatortech is the world leader in shorted turn detection

product design and analysis. Knowledge of the shorted turn conditions of your field windings

will help your plant operators and engineers pinpoint the cause of abnormal vibrations, assist in

major maintenance decisions, and verify the quality of rewound rotors.