Stator Construction

Stators: From the lamination steel to the frame material to the windings, Kato Engineering's stators are precisely designed and constructed to ensure peak generator performance and operating life. 

Frames: Sophisticated design software and over 75 years of experience ensure that the generator frame is made with strength and support where needed instead of just adding useless size and weight. Stator frames are welded with heavy rings and bar steel. The frame is reinforced with welding plates between bars or with a heavy wrapper. Heavy gauge steel is formed and fasted to the frame to provide an ample airflow path. The endbells are precisely machined to support the bearing brackets.

Form-wound windings: Because of the high voltages they incur and their importance to generator performance and life, the stator coils are the heart of a generator. Kato Engineering uses modern and precise equipment to make these coils. Insulating tapes are precisely layered to ensure maximum insulation properties and optimum fit in the coil slot, eliminating discharges that would shorten the generator's operating life.

In the stator, coil end windings are supported with surge ropes and blocking material to withstand short-circuit fault conditions. Entire stator assemblies are immersed into liquid epoxy resin and vacuum-pressure impregnated. The vacuum exhausts air and moisture from the windings and permits complete penetration of the epoxy resin during the pressure cycle, filling voids and creating a rigid mass with optimum dielectric strength. 

Rotor Construction

Rotors: For long, smooth operation Kato Engineering rotors are precisely made with the highest quality components. State-of-the art equipment ensures the most stringent manufacturing requirements are met.

Rotor pole shape is designed to withstand mechanical stresses caused by rotational forces and prime mover pulsations. The pole contour is optimized to minimize harmonics in the voltage waveform.

Field coils are machine wound on the poles with high temperature rated insulated copper wires. The coil end and interpolar region are blocked to prevent coil movement and distortion. Depending upon the application, damper bars are inserted into the pole face and brazed or welded at each end to complete the damper/amortisseur winding. The purpose of the damper windings is to reduce the generator harmonics and absorb torque pulsations caused by the prime mover or an unbalanced load distribution. The damper windings also reduce system oscillations caused during parallel operation. The rotor is either vacuum-pressure impregnated or wet wound.

The shaft is precision machined to meet the stringent tolerance requirements for runout and concentricity of the shaft bearing surfaces. The rotor is dynamically balanced to meet specifications.  For large sizes or special applications, a solid rotor (rotor current shaft in one forged piece) is provided.