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GE Power Systems
Revision Date: 02/10/2000Revision Date: 02/10/2000 Property of Power Systems University- Proprietary Information for Training Purposes Only!Property of Power Systems University- Proprietary Information for Training Purposes Only!
Introduction to GE Generators
GE Power Systems
Revision Date: 02/10/2000Revision Date: 02/10/2000 Property of Power Systems University- Proprietary Information for Training Purposes Only!Property of Power Systems University- Proprietary Information for Training Purposes Only!
Objectives
• Understand the basic GE generator.• Understand what the following components do:
– Rotor
– Collector Rings
– Brushes
– Stator Frame
– Stator Core
– Stator Windings
– Stator Connections
GE Power Systems
Revision Date: 02/10/2000Revision Date: 02/10/2000 Property of Power Systems University- Proprietary Information for Training Purposes Only!Property of Power Systems University- Proprietary Information for Training Purposes Only!
• GE electrical generators are totally enclosed units that use Hydrogen or Air as the cooling medium.
GE Generators
GE Power Systems
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GE Generators
• The generator is supplied with:– a self contained
ventilation system that includes gas coolers, fans, and filters..
GE Power Systems
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GE Generators
• GE machines are designed for continuous operation.
• Temperature Detectors (RTD’s) permit the measurement of winding and gas stream temperatures.
GE Power Systems
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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 Systems
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Generator Rotor
GE Power Systems
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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 Systems
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• DC current is supplied to the rotor by an excitation system or “Exciter” (aka Voltage Regulator).
GE Power Systems
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• Longitudinal slots cut into the rotor body hold the field coils.
• Additional slots provide rotor ventilation.
The Rotor
GE Power Systems
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• 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 Systems
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The Rotor
GE Power Systems
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• DC is applied to the rotor through slip rings (collector rings) and carbon brushes.
The Rotor
GE Power Systems
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• Collector Rings are made from copper, brass or steel and are insulated from the generator shaft.
The Collector Rings
GE Power Systems
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• Larger generators will use steel collector rings to 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 Systems
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• Steel collector rings will have a groove cut into the face for cooling and for proper brush wear.
The Collector Rings
GE Power Systems
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• 48 Brushes are used in 7FA applications.
• Carbon is chosen because:– Excellent Conductor– Cheaper– Natural Lubricant
The Brushes
GE Power Systems
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Current into the page
Current out of the page
Centerline of Poles
A
A
View A - A
ROTOR w/Field Windings
+
-
GE Power Systems
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The Stator
GE Power Systems
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The stator is composed of three major elements:
The Frame
The Core
and
The Windings
The Stator
GE Power Systems
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The Stator
GE Power Systems
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The Outer Frame
• The Outer Frame:– Gas Guide
– Explosion Proof Barrier
– Sound Proof Enclosure
– Grounded
GE Power Systems
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The Inner Frame
• The Inner Frame:– Supports the Core
and Windings
GE Power Systems
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Stator Frame
GE Power Systems
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Stator Core
Up to 350,000 individual laminations.
GE Power Systems
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Stator Core
Laminations or punchings are assembled on machined key bars (ribs) and are separated into packets by small space
blocks to provide ventilation ducts.
GE Power Systems
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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 Systems
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Stator Core
Once assembled tightening is accomplished with a hydraulic ram which can apply a total load of up to
1200 tons.
GE Power Systems
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Stator Core
The end result is that the core behaves similar to that of a solid cylinder.
GE Power Systems
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Stator Core
GE Power Systems
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Stator Core
GE Power Systems
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Stator Windings
GE Power Systems
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Stator Windings
• Each phase is split into groups of windings 180o apart.
GE Power Systems
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The Stator• The stationary component of
the generator.
• The stator or “armature” is where generator voltage and current is induced.
GE Power Systems
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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 Systems
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Stator Windings
• The stator bars are composed of insulated copper conductors (strands) transposed by the “Roebel” method.
GE Power Systems
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The Stator
GE Power Systems
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• 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 Systems
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• 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
GE Power Systems
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Stator Arrangement
GE Power Systems
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A
AView A-A
GE Power Systems
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Centerline of Poles
Centerline of Flux
Flux Pattern inside the generator when the unit is:
OFF LINE
@ RATED Terminal volts
GE Power Systems
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A
AView A-A
GE Power Systems
Revision Date: 02/10/2000Revision Date: 02/10/2000 Property of Power Systems University- Proprietary Information for Training Purposes Only!Property of Power Systems University- Proprietary Information for Training Purposes Only!
Draw the AC WaveformIn
duce
d V
olta
ge
TB1-06