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hydraulic governors
Different loads can be maintained in a two generators running in parallel.

Can somebody explain me how different loads can be maintained in a two generators running in parallel.
say one generator is running on auto mode and the other on manual mode (to limit the max load that can be taken), how does the hydraulic governor get affected by changing over to manual?

Please join the community. The hydraulic governor has nothing to do with it. It only moves the fuel rack.
The speed controller/load share unbit does all the work and then drives the hydraulic governer.
What gear do you have on the engines (actuator/governer, speed controller, load shar eunit etc)?
Let us know and maybe we can help.

Hydraulic governors are proportional only controllers. The set point is adjusted by a motor which drives a mechanism in the governor. If you plot frequency on the "Y" axis against load on the "X" axis then this will be a line that starts at some nominal frequency at no load and declines to some lesser frequency at full load. The difference between no load and full load frequency is called "governor droop" and is typically around 5% of nominal system frequency. Adjusting the set point moves this line up and down.

If both machines run in this simple mode then both machines will respond to load changes and the speed of both machines will vary. The operator will have to make manual adjustments to their set points to maintain desired system frequency. Suppose they have identical 5% droop characteristics and are both adjusted so that they run at desired system frequency at half load. At no load the frequency will be 2.5% high and at full load it will be 2.5% low.

The governor motor can be operated by an external control system to maintain system frequency. If this is done on one machine and not the other then the machine without an external set point will run at fixed load and the one with the external automatic frequency control will maintain system frequency by taking all load changes.

There can be other mechanisms to limit load on a particular machine but if you understand the basics of the above then you will be able to work out any other particular features that may be available on your machines.