DESIGN, WINDING, & ASSEMBLY
It is our standard practice to incorporate the following procedures when rewinding power transformers. A project manager will be assigned to this project to verify that your specification is followed completely.

CORE
The existing coils are removed from the core and the core is removed from the structure to completely reinsulate the core from the structure. At this point the only components that are recycled are the core steel and transformer tank.

TANK
The tank is pressure tested to ensure integrity and any areas of concerns are either machined (in the case of gasket surfaces) or welded to ensure the integrity.

COILS
All coils will be balanced to minimize short circuit forces. A computer short circuit analysis of the new design will be made to determine short circuit forces and stresses the coils will receive. (NOTE: See Short Circuit Analysis). As required, steel clamping structure, tip rods, and jack bolts will be modified as needed to meet forces. At a minimum, high density insulation material will be used for coil forms, spacers, etc. All coils will have thermally upgraded paper insulation and will be wound utilizing techniques equivalent to the latest factory procedures.

GASKETING
New gaskets will be installed to seal all accessories, bushings, and other devices attached to the transformer both oil to oil and oil to air. The interior of the tank, the radiators, and the core structure will be flushed and cleaned.

INSULATION
The original insulating material used between the core and the tank will be replaced with new insulation.

DEHYDRATION
After rewinding, and assembly of the rebuilt core and coils, the entire unit will be dried in our State of the Art Auto-Clave. This insures that the final product will maintain a power factor of less than .5%. After the transformer has been placed back into the tank a secondary dry-out will occur, that involves vacuum and hot oil treatment prior to testing.

Application of the finish coat, after all tank surfaces have been properly cleaned,
prepared, and primed, will be with ANSI 70 light gray paint. The transformer will be tested and certified test reports will be provided. A new Stainless Steel nameplate will be provided. The transformer will then be prepared for shipping. During the entire process you or your representatives are welcome to visit the facility and inspect the work.

SHORT CIRCUIT ANALYSIS
We use a short circuit analysis program developed in Norway. We prefer this program because it performs comparably to the General Electric Short Circuit Analysis Program. With the system impedance set to zero (infinite bus, never realized in actual conditions), the program analyzes the windings in their rated position and all tap extremes. The axial and radial forces are computed for all winding segments along with the total force transmitted to the upper and lower clamps. The latter allows our mechanical engineer to analyze the clamping structure components to determine what modifications will be necessary to insure it will withstand maximum short circuit forces.

TESTING
The following tests will be performed and certified test reports will be provided: