The UG MAS is a pressure compensated, hydraulic governor designed to accept a standard 4-20 mA electrical current signal to set the speed of the governor.
An internal pump, relief valve, and accumulator system maintain the governor operating pressure. A self-contained sump stores the oil and so reduces the possibility of contamination from outside sources.
Oil flow to and from the governor power cylinder assembly is controlled by a ballhead and pilot-valve assembly. The power cylinder positions the fuel rack, fuel valve, or steam valve of the engine or turbine. Governor stability is provided by an adjustable needle valve and a spring-loaded buffer compensation system.
A separate UG MAS electronic driver box receives the 4-20 mA speed signal. This input signal is set to correspond to the required speed range using two potentio-meters. The driver actuates a stepper motor that moves the speeder rod. The position of the speeder rod determines the compression of the speeder spring, which determines the speed set point.
The position of the stepper motor and the speeder rod is fed back to the driver by a position sensor coupled to the motor.
Two potentiometers on the driver box separately set the ramp-up and ramp-down rates of the speed-setting actuator.
A knob on the governor provides a means of manual speed setting. During electrical operation, this manual speed setting follows the electrical speed setting. On loss of electric power, the governor speed remains at the last speed setting. This set point can be changed with the manual speed setting.
Speed Droop permits load division and balancing among prime movers operating in parallel to drive a common shaft. Speed droop can be set with a knob on the front panel.
A Minor Alarm contact on the driver box can be used to limit the maximum speed setting (for example, in case of low lube oil pressure or high cooling temperature). This reduced speed setting is adjustable with a potentiometer in the driver.
Mechanical endstops for the minimum and maximum speed are easily adjustable.