171.Governor types

1. Mechanical or Direct acting type

    When the movement of the flyweights directly operate the engine fuel control rack, it is         called a direct acting governor.

    They need huge fly weights so that enough power can be obtained for moving the racks.

2. Mechanical / Hydraulic, Relay or Indirect acting type

    This type has the movement of the flyweights operating a pilot valve plunger only.

    The operation of the rack being through a power piston operated by hydraulic pressure         controlled by the pilot valve.

3. Electronic governor

    The speed governor can considered to be of three main parts,

    1. Speed sensing

    2. Control function

    3. Actuator.

    An electronic governor may have its speed sensing and the control functions                         electronically carried out.

    The actuating of the rack may be done by an electric motor or by a pneumatic actuator.

AE GOVERNOR

It is a constant speed governor, within a narrow range, speed variation is possible for synchronizing of alternators.

Speed droop setting is needed since generators have to run in parallel. If stable division of load is to be achieved, isochronous operation is not possible.

The remote speed setting is by an electric motor driving the speeder spring setting mechanism.

The power output of the governor is less since the engine is small.

The generator governor should be able to maintain engine speed during load changes as laid out by rules. (see below)

Requirements of A/E governor

With a load change of 25 % of the full rated load, the speed change is not greater than 2.5 %. Within two secs the speed should remain within one % of the final steady state speed and within four secs, the speed should be within half % of the final steady state speed.

ME GOVERNOR

The main engine governor is a variable speed governor which allows speed to be controlled form lowest to the maximum limit.

Speed droop setting is not needed other than for twin engine vessels which feed into a common shaft for driving the propeller. Twin engine vessels where there is no mechanical  coupling between engine do not have to have speed droop setting.

The remote speed setting is pneumatic, either through a positioner with a lever type governor or by pneumatic / hydraulic built in arrangement. Being used on large engines, the power output is higher and an amplifier is used in case the power output is not sufficient to move the rack.