CAT Titan 250 - Manual (Page 15)

Turbomachinery Package Specification Titan 250 Generator Set
5 Generator and Associated Equipment
5.1 General Description
For maximum flexibility, the gas turbine package can be provided with several different
generator types and voltage outputs to accommodate a broad range of application
requirements. The generator, exciter, and control system are integrated to provide
optimal performance.
The standard generator type supplied is open drip-proof (ODP) (Figure 6). However the
following other enclosure types are available to meet a variety of environmental
conditions and cooling requirements:
• Closed air circuit air cooled (CACA)
• Closed air circuit water-to-air cooled (CACW)
• Totally enclosed air-to-air cooled (TEAAC)
• Totally enclosed water-to-air cooled (TEWAC)
Figure 6. Typical Open Drip-Proof Generator with Permanent Magnet Exciter System
5.2 Functional Description
During generator operation, three-phase AC power generated by the exciter armature is
converted to DC power by a rectifier. The DC output from the rectifier is applied as field
excitation current to the generator rotor windings to create magnetic flux. The generator
voltage output is controlled by the generator field current and the generator field current
is controlled by a brushless exciter. The amount of DC current applied to the exciter field
determines the exciter output voltage. A potential transformer senses the bus potential
and provides a signal to the combined generator control module (CGCM) for excitation
control.
© 2008 Solar Turbines Incorporated. All rights reserved. TPS250GS/908 - Preliminary
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