Introduction of hydro generator
It is a water-to- wire generator with the turbine as the prime motor. When the water flow goes through turbine, it changes the water power into mechanical energy. After the rotation of the rotor of generator driven by turbine’s spindle, it changes the mechanical energy into electricity power to output. hydro generator is the main power equipment to making electricity energy in a hydropower station.

The capacity of generator range from 100KW to 200MW. And the range of its voltage is 0.4kV-13.8kV; The insulation class includes B/F-grade. Hydropower generator is driven by hydro turbine.

The types of hydro turbine
Horizontal type generators Vertical type generators
Types of hydro generator
According to its axis location, hydro generator is usually divided into two types: horizontal and vertical. Large and medium-sized units usually adopt the vertical type layout, whose max. speed can reach 750 r/min. While horizontal type usually is used for medium and small capacity units, whose max. speed can reach 1500 r/min.

As per its excitation mode, Hydro generator can be classified as brushless excitation unit and excitation with brush generator.

Capacity and speed class of hydro generator :

Type

Rated power Pn (kW)

Rated speed Nn (r/min)

Low

Middle

High

Micro hydro generators

<100

 

750-1500

Small hydro generators

100-500

<375

375-600

750-1500

Medium-sized hydro generator

500-10000

<375

375-600

750-1500

Huge hydro generator

>10000

<100

100-375

>375

Structure of hydro generator
Hydro generator usually consists of the following major parts: Rotor, stator, frame, thrust bearings, guide bearings, cooler, brake, etc. The rotor and stator are the main parts of the product for electromagnetic effect. Other parts are for support or subsidiary use only. The rotor is the main part for transforming energy and delivering torque, which consists of the main shaft, rotor frame, magnetyoke(torus) and pole, etc.. Stator consists of base, iron core and three-phase winding coil , etc.. Stator core is made of cold-rolled silicon steel , which can be made into an entirety and split structure as per the manufacturing and transportation requirements. The type of cooling for Hydro Generator usually uses closed loop air cooling (ONAN). The huge capacity unit is apt to use water cooling to cool the stator directly. If both the rotor and stator need to be cooled at the same time, it should be dual cold water cooling inside turbine generating unit .

The installation structure of the hydro generator
The installation structure of the hydro henerator is confirmed by the type of turbine. It mainly includes the following styles:
Horizontal structure
Usually, the horizontal hydro generator drives by Pelton turbine. Horizontal turbine usually uses two or three bearings. The structure of two bearings is short in its axial length, compact structure, and easy to install. But when the combined critical speed canít meet the requirement or the bearing load is large, three bearing structure should be used.

Vertical structure
The domestic hydroelectric generating units widely use vertical structure. Usually, the vertical hydro generator drives by Francis or Kaplan turbines. It also can be classified as hanging and umbrella type. It is called hanging type that thrust bearing of generator is upper on the rotor. While it is called umbrella type, its thrust bearing of generator is under the rotor.

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