Actuator
As shown in Figure 4-2, the actuator is mechanically simple. It has specially
designed rotor and stator shapes which provide reliable, effective performance.
The rotary design gives 35° * shaft rotation to low-mass, low-friction fuel controls.
The magnetic circuit, when powered by the speed control, applies torque in the
increase-fuel direction. Two ** preloaded internal return springs supply shaft
torque in the decrease fuel direction. The preload can be factory reduced to
compensate for some external linkage forces acting in the decrease fuel
direction.
*—For 1712/1724 Actuators, and 30° for 512/524 Actuators.
**—Two springs for 1712/1724 Actuators; one spring for 512/524 Actuators.
Figure 4-2. Actuator Schematic
Applications Using a Ramp Generator
The Ramp Generator slows the speed change between idle and rated speeds. It
has no effect on steady-state speeds. Once set it provides a constant speed
change per second by biasing the speed reference when changing from idle to
rated and vice versa. The accel and decel pots control the rate of change.
Acceleration and deceleration times depend on accel and decel pot settings and
the difference between idle and rated speeds.
Paralleled Generator Applications
A Load Sensor is used with the EPG for isochronous or droop paralleling.
With an isolated bus, isochronous load sharing is usually chosen. In an
isochronous load sharing system, the load gain signal voltage is shared with all
other controls through paralleling lines, and provides an average load gain signal
used by the controller circuits.
