How long should be a turning gear be operated?

In a single S109FB turbine shaft configuration, the time that the unit must remain in turning gear, at a minimum should be four hours, before the start if the shaft is stopped.

How long does it take to warm up a steam turbine?

approximately five to nine hours
They should be warmed up and cooled down slowly to minimize the differential expansion between the rotating blades and the stationary components. Large steam turbines may require approximately five to nine hours to warm up.

Why do we use turning gears?

A reversible electric motor which, through a system of gears, can be used to turn slowly a large diesel engine or steam turbine and gearbox assembly. It enables precise positioning for overhaul or examination. The engaging and disengaging of the turning gear is accomplished by the lever.

What is turning gear operation?

marine. A reversible electric motor which, through a system of gears, can be used to turn slowly a large diesel engine or steam turbine and gearbox assembly. It enables precise positioning for overhaul or examination. The engaging and disengaging of the turning gear is accomplished by the lever.

How does a turning gear work?

The turning gear assembly typically consists of an electric motor connected to a set of reduction gears that mesh with a corresponding bull gear attached to the turbine rotor. The electric motor torque is converted to slow-speed rotation of the turbine rotor through a series of gear reductions.

Why does a steam turbine have a turning gear?

If a warm turbine rotor sits, gravity will cause the heavy rotor to bend or sag on the beating. The turning gear very slowly rotates this shaft (rotor) so there is no sagging. The turning gear operates from an electric motor and is disengaged when it is time to flow steam.

Why must the turbine rotor be manually turned by one revolution?

Prior to repeated switch on of the turning gear, turbine rotor must be man- ually turned by one revolution in order to check if rubbing has not taken place. If rubbing is found it is necessary to wait until the rotor rotates freely and only then the turning gear can be repeatedly switched on. Steam turbines start-ups 171

What happens during the cold start up of a turbine?

During cold start up of a turbine, steam is not let into the turbine with full pressure and flow. Instead, steam is let in at a relatively small flow rate so as to heat up the turbine parts and attain thermal equilibrium. For facilitating uniform heating of turbine rotor, it is rotated at a slow but constant speed using a Turning gear.

What happens to the turbine when it is shut down?

During shut down of the turbine, it is never brought to standstill condition instantaneously. The speed of the turbine is slowed down to a certain level by reducing steam flow through it.