What is barring gear in turbine?

Barring gear (or “turning gear”) is the mechanism provided to rotate the turbine generator shaft at a very low speed after unit stoppages. Once the unit is “tripped” (i.e., the steam inlet valve is closed), the turbine coasts down towards standstill.

What is the main purpose of a turbine?

A turbine is a device that harnesses the kinetic energy of some fluid – such as water, steam, air, or combustion gases – and turns this into the rotational motion of the device itself. Turbines are generally used in electrical generation, engines, and propulsion systems.

What is turbine hogging?

In the time it takes for a turbine to come to a complete stop following shutdown, the casing and rotor hardly cool down at all. This results in a greater contraction of the bottom of the rotor than the top. The differential contraction results in an upward bowing of the rotor called shaft hog.

What is barring over?

Definition of barring : excluding by exception : excepting …

What is barring of compressor?

The compressor should be fitted with a barring device (barring gear), which can be manual, electrical or pneumatic. This device is used only for maintenance, while the compressor is stopped.

Which principle is used in hydralic turbines?

Answer: Newton’s second law of motion The hydraulic turbine’s principle is based on Newton’s second law of motion. The force is directly proportional to the change in momentum, according to this law.

What causes shaft bow?

The friction forces due to light rotor-to-stator rubs in rotating machines can cause a time-varying thermal bow of the shafts. Owing to this, stable partial arc rubs and full-annular rubs can induce mainly progressive changes in the synchronous vibrations of the rotor-trains.

How does a gear motor 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.

What is a turning gear?

A jacking gear (also known as a turning gear) is a device placed on the main shaft of an engine or the rotor of a turbine. The jacking gear rotates the shaft or rotor and associated machinery (such as reduction gears and main turbines), to ensure uniform cool-down. Without turning, hogging or sagging can occur.

When should I use Barring?

You use barring to indicate that the person, thing, or event that you are mentioning is an exception to your statement. Barring accidents, I believe they will succeed.

What is barring speed in turbine?

What is the barring speed of turbine? – Quora. Typical barring speeds vary for different manufacturers depending on the required moment to roll out the sagging. As far as my operational experience goes it varies between 20 – 50 rpm.