Turbine Package Operators Manual
Chapter 1
Turbine Package System Overview
1-33
Gearbox and Generator
Gearbox
The main gearbox located between the gas turbine and the generator provides speed reduction
of the turbine output shaft to that suitable for operation of the generator.
The gear unit is a single reduction parallel shaft speed reducer with vertical offset. Lubrication of
the gear units and bearings is provided by the gas turbine lubricating oil system. The gear unit is
foot mounted on to the underbase.
Gearcase-mounted accelerometers provide indication of excess vibration.
The information contained within this section provides an overview of a typical gearbox and
associated equipment. For specific manufacturer information, refer to the Driven Unit Manual.
Generator
The generator is of salient-pole construction with brushless excitation, and a permanent magnet
generator (PMG) for automatic voltage regulator (AVR) power supply. The design incorporates
accessibility to facilitate commissioning, operation, inspection and maintenance.
All the component items of the generator are fixed to the base frame, which is the main
structural member. It carries the end brackets and bearings, the stator corepack and the cooler,
which is mounted on top. The exciter and PMG stators are fixed to a bracket mounted on the end
bracket at the non-drive end (NDE). Terminals are mounted off the frame, either all on one side
or lines one side and neutrals on the other, as required.
The information contained within this section provides an overview of a typical generator and
associated equipment. For specific manufacturer information, refer to the Driven Unit Manual.
Cooling System
A fan, mounted on the generator rotor shaft, provides circulation of cooling air to the electrical
windings of the rotor and stator. This circulating cooling air inside the machine is sealed in and is
cooled by passing it through an air cooled heat exchanger mounted on the top of the generator.
The air flow to the heat exchanger is induced by fans mounted in the air inlet.
A pressure differential switch monitors air flow to the heat exchanger.
The temperature of cooling air to the generator windings is monitored by resistance temperature
detectors.
Generator Bearing Lubrication
The generator bearings are supplied with lubricating oil from the turbine lubricating oil system.
One resistance temperature detector is fitted to each bearing housing. This monitors bearing
temperature and provides warning and turbine shutdown functions if the temperature levels
reach predetermined levels.
