10.3.1.2. Speed Control Unit for Governor System
(DWC-2000 SERIES SPEED CONTROL UNIT)
<Introduction>
This speed control unit performs the electronic function of the engine governing system.
The speed control unit senses the pulses from the magnetic speed sensor, compares them
with the speed control unit's set point and supplies the appropriate current output to the
actuator to control the engine's fuel system.
An integral, independent single element speed switch is provided internally which can be
used to initiate engine shutdown in the event that an overspeed condition is reached. The
performance of the speed control unit is fast and responsive in either isochronous or droop
operation.
Adjustments are provided for: operating speed, idle speed, overspeed shutdown setting,
droop, run ramp, crank ramp, starting fuel, speed ramping and two performance
adjustments(gain and stability). All adjustments are accessible from the front cover. The
primary features of the DWC-2000 Series speed control unit are the engine STARTING
FUEL and SPEED RAMPING adjustments. The use of these features will minimize engine
exhaust smoke experienced prior to attain engine operating speed. The speed control unit
also includes other features such as adjustable droop and idle operation, inputs for
accessories used in multi-engine or special applications and protection against reverse
voltage polarity, transient voltages and accidental short circuit of the actuator. Loss of
battery supply, loss of speed sensor and overspeed signaling are built-in to provide engine
shutdown.
<Description>
- 119 -
EC8OM007
CONTROL UNIT
-
+
Output
Circuit
Actuator
Battery
DROOP
SWITCH
Pulse/second = Hz
0.45 mm
M
G
B
A
E
F
K
L
D
C
PID
Controller
Droop Adjustment
Speed Adjustment
Stability Adjustment
Gain Adjustment
Starting Fuel
Adjustment
IDLE Speed
Adjustment
FV
Converter
Speed Ramp
Adjustment
Figure 1. Governor system schemetic
