A customer contacted us to work on a TGF 5000 hp motor.  Trisonic Gasdynamics Facility.  What in the heck is a TGF.  A wind tunnel.  The AFB tests airplane models in a wind tunnel.  The wind tunnel air speed maximum is mach 3.5.  The 10 stage Allis Chalmers compressor requires 8500 hp.  A 3500 hp wound rotor motor couples to a Falk gearbox with the 5000 hp synchronous motor.

This job started with the Springfield field service department. Jim Delawder inspected and tested the motor, determining that rewinding was needed. John Franzer and Mike Harper presented a quotation for repair to the customer. After some sticker shock and some questions and answers, we were presented with the order to rewind the motor. After receiving the 3600 RPM synchronous motor, we observed the rotor design is different than previous synchronous motors we repaired.  This rotor is a generator rotor used in a motor application.   The Westinghouse motor manufacture was 1942.  After several discussions with our customer, we agreed the repair work scope includes rotor and stator rewind.  Both rotor and stator windings were the original 1942 manufacture.

Toshiba America Energy Systems was contacted to outsource the rotor rewind to a power generation repair facility.  Partnering with Toshiba made sense, since we are a distributor of Toshiba motor/drive products.  Rotor photos, dimensions, and nameplate data were sent to Toshiba and we received a rotor rewind, possible asbestos abatement, and high-speed balance work scopes. Bert Serak was designated as the point man for the rotor work with Toshiba, due to his extensive background in power generation and large equipment repair.

After several discussions with customer, including potential asbestos in rotor & stator, repair work was authorized.  Of course, we found asbestos in the rotor and stator, since this unit was produced pre-WWII.  Toshiba performed rotor and Horner performed the stator asbestos abatement. The stator rewind was completed on time at our Horner Washington Street shop. Special thanks to Mike Butler, Randy Jones, and Alan Horner for their assistance with the stator rewind. The rotor rewind had delays caused by the asbestos abatement.  Asbestos was found in all 10 coils and 20 core iron slots.  Another delay was caused by the unusual 1942 design of an insulated ring between the core iron and retaining ring.  The retaining ring is the mechanical ring holding the coil end turns against the shaft to eliminate coil movement during operation.  During high speed balance, rotor turning at 1900 rpm, vibration amplitude and phase angle continually change.  Retaining ring movement was identified as cause and high-speed balance was stopped.  The retaining rings were removed.  Toshiba engineering manufacture new end discs and supplier manufactured new insulated rings.  Assembly was completed and high-speed balancing was scheduled.    A very unfortunate catastrophic incident occurred during balance.  The drive shaft/coupling to rotor failed and caused damage to 5000 hp rotor shaft coupling fit.  Shaft machine work and a new coupling hub was installed.  The high-speed balance was completed.  At 3600 rpm, electrical tests were performed on rotor windings and all test measurements were very acceptable. Our Washington Street shop assembled the rotor in stator.  The Springfield division field service provided technical direction during motor installation at the customer site.

During motor commissioning, the wind tunnel engineers said the motor operation was never so smooth.  Vibration levels were lower after repair.  Stator winding and bearing temperatures were normal.  Wind tunnel testing at the 3.5 Mach speed is complete.  Customer is exceptionally happy with Horner Industrial service and the teamwork of Indianapolis and Springfield.  One company, one team, one happy customer.  Discussions are already in the works to recondition the 3500 hp wound rotor motor.