7FH2 Gen Fund Construction

GE Power Systemsg

Revision Date: 02/10/2000 Property of Power Systems University- Proprietary Information for Training Purposes Only!

Introduction to GE Generators

GE Power Systemsg


GE Power Systemsg


Rotor is rotated by a mechanical setup

Field coils placed in the rotor slots are excited by DC current - produces a

rotating magnetic field (Amperes Law).

Three phase stator coils cut by the varying flux produces sinusoidal

voltage (Faradays Law).

How Generator Works?

Rotor

Air Gap

Rotor Slot Coil

3 phase coil

Stator

GE Power Systemsg


7FH2 Generator

RotorStator

Stator Winding

Coolers

Collector Brushes & Rings

Turning Gear

Terminal Enclosure

Introduction to GE Generators

GE Power Systemsg


GE electrical generators are totally enclosed units that use Hydrogen or Air as the cooling medium.

GE Generators

GE Power Systemsg


GE Generators

The generator is supplied with: a self contained

ventilation system that includes gas coolers, fans, and filters..

GE Power Systemsg


7FH2 Cooling Flow Path

GE Power Systemsg


GE Generators

GE machines are designed for continuous operation.

Temperature Detectors (RTDs) permit the measurement of winding and gas stream temperatures.

GE Power Systemsg


GE Generators

The generator is constructed to withstand all normal conditions of operation as well as short circuit faults.

Hydrogen cooled units are capable of containing an internal explosion.

GE Power Systemsg


The Stator

GE Power Systemsg


The Rotor is a simple bar magnet that has DC flowing through it and is turned by either a steam or gas turbine.

GE Power Systemsg


DC current is supplied to the rotor by an excitation system or Exciter

GE Power Systemsg


The rotor receives DC current from the exciter and creates a rotating magnetic field.

The rotor is machined from a single alloy steel forging.

The Rotor

GE Power Systemsg


Longitudinal slots cut into the rotor body hold the field coils.

Additional slots provide rotor ventilation.

The Rotor

GE Power Systemsg


GE Power Systemsg


DC is applied to the rotor through slip rings (collector rings) and carbon brushes.

The Rotor

GE Power Systemsg


Larger generators will use steel collector ringsto compensate for large amounts of heat that can be generated.

Rings are orientated such that the (-) negative ring is inboard (closest to the generator) and the (+) outboard.

The Collector Rings

GE Power Systemsg


GE Power Systemsg


The Stator

GE Power Systemsg


Stator Core

Laminations or punchings are assembled in an interleaved manner on machined keys (ribs) and are separated into

packets by small space blocks to provide ventilation ducts.

GE Power Systemsg


Stator Core

Up to 350,000 individual laminations.

Each approximately 0.020 (0.50 mm) thick

GE Power Systemsg


Stator Core

The laminations must be carefully aligned and checked to ensure that the stator bars will fit accurately into the

slots and maintain the required specific clearances.

GE Power Systemsg


Stator Core

GE Power Systemsg


Stator Windings (stator or armature windings)

GE Power Systemsg


Stator Windings

The stator windings are composed of insulated bars assembled in the stator slots, joined at the ends to form coils, and connected to the proper phase belts by bus rings.

GE Power Systemsg


GE Power Systemsg


M

89ND-1

DGP

89SS-1

52G

Rotor

M

From LCI

Stator Arrangement

GE Power Systemsg


In a simple generator, the field winding or Rotor is rotated under 3 sets of armature or Stator windings.

These windings produce 3 distinct outputs that are 120o apart.

Three Phase AC Generation

GE Power Systemsg


Each stator winding or phase is actually several windings connected in series.

Windings connected in series increase the voltage in each phase. This is desirable to limit the strength of the excitation current.

Three Phase AC Generation

7FH2 Gen Fund Construction

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