The turbo generator is an electrical generator that is connected to the shaft of a steam turbine or gas turbine for electric power generation.
Turbo generators are employed for high shaft rotational speeds (usually steam and gas turbines). Its rotor is of non-salient pole-type construction that usually has two poles.
Two pole turbo alternators operate at 1500 or 1800 RPM in case of 50 and 60 Hz frequency. While 4 pole turbo alternators operate at 3000 or 3600 RPM (in case of 50 and 60 Hz).
Rotor Construction in Turbo Alternators
The rotor of turbo alternator is made from solid forging of alloy steel in order to make it mechanically resistant. The rotor is of non-salient pole construction. The surface is milled, forming the slots. In practice two-third of surface is kept slotted while rest is kept unslotted. The coils employed are of concentric multi-turn type.
Stator Construction in Turbo Alternators
The core is made of segmental laminations. Slots, ventilation holes and key holes are punched together. The stator windings are three phase doubler layer and short pitched coils that are placed in slots on stator. The core is made of segmental laminations. Slots, ventilation holes and key holes are punched together. The stator windings are three phase doubler layer and short pitched coils that are placed in slots on stator.
The figure below displays Parsons first 1 MW steam turbine driven “Turbogenerator” (made 1900 for a plant in Elberfeld, Germany).
