Turbomachinery Package Specification

Titan 250 Generator Set

 

 

6 Start System

6.1General Description

The start system includes a direct-drive AC starter motor driven by a solid-state variable frequency drive (VFD). The start system provides torque to initiate engine rotation and to assist the engine in reaching a self-sustaining speed. The starter motor is mounted directly on the gas turbine accessory drive gearbox. The VFD regulates voltage and frequency to the starter motor for engine rotation as commanded by the Turbotronic 4 control system.

6.2Functional Description

To begin gas turbine rotation, the VFD initially provides low-frequency AC power to the starter motor. The VFD gradually increases the speed of the starter motor until the gas turbine reaches purging speed. When purging is completed, the control system activates the fuel system. The speed of the starter motor is gradually increased until the gas turbine reaches starter dropout speed. The VFD then deenergizes the starter motor and the motor clutch assembly is disengaged.

6.2.1Starter Motor

The starter motor (Figure 7) provides high breakaway starting torque and acceleration from standstill to starter dropout speed. The motor is standard frame size and is constructed to be explosion proof and flameproof. The motor includes an integral over-temperature protection thermostat connected to the Turbotronic 4 control system for hazardous area motor certification and protection. Separate cable entry points are provided for power connections, thermal protection wiring, and the space heater wiring. Starting power is transferred to the gas turbine via the reduction-drive gearbox and over- running clutch and shaft assembly. After a shutdown, the starter motor rotates the turbine at low speed to prevent deformation of the rotor during cool down.

Figure 7. Direct-Drive AC Starter Motor and VFD Cabinet

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TPS250GS/908 - Preliminary

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