4 ms·

Older/basic generators would run at fixed frequency to generate the correct frequency. I believe the voltage is regulated by regulating the field strength in th

by Ballas 6y ago

Older/basic generators would run at fixed frequency to generate the correct frequency. I believe the voltage is regulated by regulating the field strength in the rotor. Modern generators have inverters that handle the output and regulates the 60Hz/110V or 50Hz/220V etc. In this case the RPM is controlled by the wattage required (with a min and max RPM). Motor -> alternator -> inverter -> load

namibj 6y ago
It depends on the size. The larger the generator, the more likely you have a constant-RPM setup.
- bluGill 6y ago
  True, but that is changing. Inverters are not very expensive anymore, provide cleaner power, and can match the frequency of the something else allowing you to put several generators in parallel and disconnected one for maintenance. They also allow running lower RPM which at lighter loads can save fuel/money. (A constant rpm generator often uses more fuel at 50% load than at 80% load!) Inverter generators can also sell power back to the grid. To pay for the fuel you need more than the typical retail price of electric, so this is only worth it if you have a need for a backup generator anyway. However if you have this need talk to the power company, they often will give you a discount because when there are load issues (See Texas last week), and the ability to add power to the grid in this time will be something they are interested in. Today most large generators are still constant RPM, but I don't expect that to last.
  - namibj 6y ago
    Why would a constant-RPM generator not be able to feed into a grid? Also, you can run them in parallel without problems, as long as you keep the governors from oscillating. But proper PID tuning and sensing architecture should turn that into a non-issue. Larger engines btw. just disable cylinders for part-load operation.
    - bluGill 6y ago
      They can, and do: if the governor is good enough. Overall it is easier to use an inverter, but there are several ways to solve the problem. Cylinder disabling has a place too.

by Ballas 6y ago

namibj 6y ago

It depends on the size. The larger the generator, the more likely you have a constant-RPM setup.

bluGill 6y ago
True, but that is changing. Inverters are not very expensive anymore, provide cleaner power, and can match the frequency of the something else allowing you to put several generators in parallel and disconnected one for maintenance. They also allow running lower RPM which at lighter loads can save fuel/money. (A constant rpm generator often uses more fuel at 50% load than at 80% load!) Inverter generators can also sell power back to the grid. To pay for the fuel you need more than the typical retail price of electric, so this is only worth it if you have a need for a backup generator anyway. However if you have this need talk to the power company, they often will give you a discount because when there are load issues (See Texas last week), and the ability to add power to the grid in this time will be something they are interested in. Today most large generators are still constant RPM, but I don't expect that to last.
- namibj 6y ago
  Why would a constant-RPM generator not be able to feed into a grid? Also, you can run them in parallel without problems, as long as you keep the governors from oscillating. But proper PID tuning and sensing architecture should turn that into a non-issue. Larger engines btw. just disable cylinders for part-load operation.
  - bluGill 6y ago
    They can, and do: if the governor is good enough. Overall it is easier to use an inverter, but there are several ways to solve the problem. Cylinder disabling has a place too.