Taurus Group 60 - Manual (Page 39)

Turbomachinery Package Specification Taurus 60 Compressor Set and Mechanical Drive
The fuel control valve gradually opens and admits fuel into the combustor through the
injectors. The inlet guide vanes open and the bleed valve gradually closes. Fuel flow,
engine temperature, and turbine speed all increase. Once starter dropout speed is
exceeded, the starter freewheels and is de-energized. The engine continues to
accelerate under its own power.
10.4.2 Steady-State Control
During steady-state operation, the control system keeps the equipment within specified
operating conditions. The maximum power limit is determined by engine temperature and
speed.
Temperature control is based on the third-stage nozzle temperature (T5). Six
thermocouples are used and the values averaged. If one thermocouple has a value that
deviates from the average by more than a preset amount, an alarm is generated by the
control system. If two thermocouples deviate, the package is shut down.
Special sensors continuously monitor the gas turbine speed and the control system
makes adjustments to meet operating requirements and to keep the speed within
specified limits. A separate backup overspeed detection system provides additional
protection by automatically shutting the engine down if a preset overspeed limit is
reached.
10.4.3 Stopping
The gas turbine may be shutdown either manually or automatically.
The Normal Stop command initiates a cooldown stop. The gas compressor is
depressurized (if applicable) and the gas producer runs at idle speed for a preset time to
allow the gas turbine and driven equipment to cool, then the fuel valves close. The
Emergency Stop
command results in the immediate depressurization of the gas
compressor and closure of the fuel valves without a cooldown period.
In the event of a hazardous condition or equipment malfunction, the control system will
shut the package down automatically. These shutdowns are divided into four categories:
• Cooldown stop nonlockout (CN)
• Cooldown stop lockout (CL)
• Fast stop nonlockout (FN)
• Fast stop lockout (FL)
Cooldown and fast stops correspond to the manual normal and emergency stops
respectively. Lockout stops inhibit operation of the control system and prevent restarting
until the malfunction is reset. Lockout stops result from serious malfunctions that require
corrective action before the system can be restarted. Nonlockout stops result from an
operational disruption or abnormal condition and can be reset when conditions return to
normal.
In all cases, after the package has come to a complete stop and the rundown timer has
timed out, the control system initiates and supervises a post-lube cycle to protect the gas
turbine and driven equipment bearings from thermal damage. If the shutdown is the result
of a fire being detected, start of the post lube cycle is delayed for 10 minutes unless an
operator intervenes.
10.4.4 Vibration and Temperature Monitoring
In addition to the T5 thermocouples, the system provides continuous monitoring of
temperature and vibration levels at key package locations. Refer to the Specification
Table for details.
© 2009 Solar Turbines Incorporated. All rights reserved. TPS60CSMD/309
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