# How torque is converted into ampere in a generator

1. Apr 1, 2014

### RohitRmB

As i have read on the internet that during synchronization the prime mover connected to the turbine produces a little over than required power to keep the turbine cum generator assembly moving at the synchronous speed that is regulated by the grid frequency (In india its 50Hz). As the generator is synchronized, the speed of the turbine cum generator will remain equal to 3000 RPM (As per frequency of 50Hz). Now if more steam is admitted to the turbine, then the torque produced by the turbine will increase but the speed of the turbine cum generator assembly cannot increase beyond synchronous speed, so that increased torque gets converted into amps.
Now my question is, i am not able to understand the physics behind how this conversion of torque into amps takes place at fundamental level.
So kindly help me in this.

2. Apr 1, 2014

### mjhilger

Power generation is not really my field; however if your background is in physics, then this is all driven by Maxwell's equations. The turbine spins the generator at the specified frequency to match the grid as you state. So to change the power output the magnetic flux is controlled through the control circuits. This is an easy job these days as the computers that control the process quickly adjust the settings such that any change in input power matches the necessary output power while keeping the speed constant. In days before the computer control, operators did this by hand controls and must have been very good at their jobs!
Think of it as riding a bike. When you are on level ground you are required a certain amount of leg energy to keep a constant pedal cadence thus speed; going downhill required much less leg energy to keep the speed constant; while going uphill required much more leg energy to keep the same speed. The fields of the generator are adjusted in a similar way as you adjust your leg muscles to produce more power.

3. Apr 1, 2014

### RohitRmB

Thanks for your reply but I want to know actually which equations govern this conversion and how the generator actually knows that now speed should be constant and further addition of energy from the turbine (torque) is now to be converted to amps?
Sorry but please bear with my childish question.

4. Apr 1, 2014

5. Apr 1, 2014

### jim hardy

see if second page of thread below is any help.

The answer to your question is the Lorentz force acting on charge in the conductors, F = QV cross B.

It's discussed here with some illustrations from hyperphysics..