# Homework Help: How frequency is controlled

1. Mar 23, 2012

### kamalk26864

1.since the performence of electrical loads does not depend on frequency,why it is important to keep the frequency at 50hz.?
2.how the generating companies keep theier frequency at 50hz though loads keeps on changing..?

2. Mar 23, 2012

### yungman

Who said load don't change with frequency, some do. Anything with inductance would be affected by frequency.

50Hz is just a standard, we use 60Hz here.

Frequency is the number of cycles per second from the generator side which is the power station, it is load independent. Power station just output a 50Hz.

3. Mar 23, 2012

### vk6kro

It used to be very common to run clocks from the mains and the accuracy of the clock depended on the accuracy of the mains frequency. Although this is less common now since the quartz clocks became available, a lot of clocks in public buildings still do this because quartz clocks have to be adjusted regularly.

It is also very common to connect all generators to a grid of other generators and these have to be precisely on the same frequency and also in phase with each other. They also have to be producing the same voltage as the other generators.

Generator frequency is determined by the speed of rotation of the engine that drives the generator and this speed is set in much the same way as you set the speed on your car engine, by applying pressure to the gas pedal.
This happens automatically, though, and there may not be an actual gas pedal.