Daewoo ST Series Instruções de Operação descarregar pdf (Página 129)

The stability adjustment, when advanced clockwise, increases the time rate of response of the

governor system to match the various time constants of a wide variety of engines. The speed

control unit is a PID device, the “D”, derivative portion can be varied when required. (See

Instability section.)

During the engine cranking cycle, STARTING FUEL can be adjusted from an almost closed,

to a nearly full fuel position.

Once the engine has started, the speed control point is determined, first by the IDLE speed

set point and the SPEED RAMPING circuit. After engine speed ramping has been completed,

the engine will be at its governed operating speed.

At the desired governed engine speed, the actuator will be energized with sufficient current to

maintain the desired engine speed, independent of load (isochronous operation).

The output circuit provides switching current at a frequency of about 500Hz to drive the

actuator Since the switching frequency is well beyond the natural frequency of the actuator,

there is no visible motion of the actuator output shaft.

Switching the output transistors reduces its internal power dissipation for efficient power

control. The output circuit can provide current of unto 10amps continuous at 25?C for 12 and

24VDC battery systems. The actuator responds to the average current to position the engine

fuel control lever.

In standard operation, the speed control unit performance is isochronous. Droop governing

can be selected by connecting terminals K and L and the percent of droop governing can be

varied with the droop adjustment control . The droop range can be increased by connecting

Terminals G and H.

The speed control unit has several performance and protection features which enhance the

governor system. A speed anticipation circuit minimizes speed overshoot on engine start-up

or when large increments of load are applied to the engine.

Engine idle speed can be remotely selected and is adjustable. Accessory inputs to achieve

variable speed operation and multi-engine control can be accepted by the speed control unit

from GAC load sharing modules, automatic synchronizers.

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Daewoo ST Series Instruções de Operação Página 129