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Air-Gap Flux Probe Technology for Detecting Rotor Winding Shorted Turns

Setting Up a Shorted-Turn Condition
Monitoring Program

When planning the installation of permanent probes, the following advance planning subjects should be addressed.

Critical machine dimensions such as rotor outer diameter (O.D.), retaining ring O.D., and stator core I.D. need to be supplied to Generatortech so the flux probe can be manufactured before assembly. Generatortech will provide a drawing showing which dimensions must be supplied. If desired, Generatortech personnel will take the dimensions.

Magnetic wedges in the rotor coil slots reduce the air-gap slot leakage flux signal. Thus, shorted turn detection sensitivity is reduced in these slots. If plans are being made to assemble an air-gap probe, extra effort and possibly cost should be expended to ensure that all wedges in the leading slots at the axial position of the flux probe are non-magnetic. On some fields, this may require purchasing 2 to 4 non-magnetic wedges from the Original Equipment Manufacturer. The wedges would be used to replace the magnetic wedges near the turbine end in the slots leading the pole.

Discussions with Generatortech should be made early in the planning stages.