Woodward 723PLUS Technical Manual page 37

Manual 26482
The 723PLUS control also monitors the engine speed for an overspeed
condition. The overspeed fault will latch, and actuator output will go to the
minimum fuel position, if the engine speed is greater than the 08 OVERSPEED
SD value. This value is set in Configure mode, under the header E**ALARM/SD
CONFIGURE**, at prompt 08 OVERSPEED SD. This fault is reset when the
engine speed clears the failsafe speed like the other faults. The overspeed can
be reset by restarting the engine or using the software reset, which can be found
in Service mode, under either the header D**MINOR ALARMS**, C**MAJOR
ALARMS**, or B**DISPLAY 2** at prompt 13 RESET ALL ALARMS. Even
though the overspeed fault will cause the actuator output to go to the minimum
fuel position, IT SHOULD NOT BE USED AS THE OVERSPEED PROTECTION
FOR THE ENGINE.
Speed Reference and Ramps
The 723PLUS Two-Engine LON Torque sharing control provides for remote
speed setting, the control provides a 4 to 20 mA or 1 to 5 Vdc Remote Speed
Setting input.
The 723PLUS for the first engine clutched in is the master, which responds to the
speed reference inputs and uses all internal speed reference ramp rates. The
723PLUS for the second engine clutched in is the slave, which ignores all
internal speed reference ramp rates and exclusively follows the master speed
reference. The slave receives the master speed reference over Control LON.
The torque sharing signal, sent over Control LON, biases the speed reference of
each engine to effect torque sharing after both engines are clutched together.
Input functions are enabled as follows:

The Maneuvering Mode speed setpoint is selected when this discrete input
is closed on the master unit. The speed reference will be the setting of the
06 MAN MODE SPD STPT in the A**CONFIG SPD CONTROL** menu.
This section describes the operation of the speed reference and ramp functions
and their relation to each other. Read this section carefully to be sure your
sequencing provides the proper operating modes.
The idle speed set point is provided for engine start-up and for clutching in the
first engine. The idle reference is selected, at a very fast rate, by control power-
up or whenever the engine is not running, if 04 IDLE REF @ SHUTDOWN found
in configure mode under the header A**CONFIG SPD CONTROL**, is configured
TRUE. The idle reference is also selected by a clutch request, when neither
engine is clutched in, to ramp engine speed to the idle reference at the decel
ramp rate. Idle speed may be set equal to or less than the rated speed set point.
Idle is independent of the lower limit set point and may be set to a lower speed.
Idle speed set point cannot be changed except through adjustment of the idle
speed set point.
Woodward
The engine, turbine, or other type of prime mover should be
equipped with an overspeed shutdown device to protect against
runaway or damage to the prime mover with possible personal injury,
loss of life, or property damage.
The overspeed shutdown device must be totally independent of the
prime mover control system. An over-temperature or over-pressure
shutdown device may also be needed for safety, as appropriate.
723PLUS Digital Marine Control
27