3.02
, Gas
Safety, Control and Monitoring System
Page 3 : 9
0211 BC
• Prechamber pressure regulation
• Ignition control
• VVT control (Variable valve timing)
Data to and from the governor will be through hard-
wired signals either directly to the governor or
trough remote IO modules located in the ECC and
on the engine.
The fuel actuator signal output will supply 0-200mA
controlling the fuel actuator for C type engine and
0-1A for a B type engine.
The governor works with closed loops to perform
the different task, and has built in error and sensor
fault detection. The governor signals the status to
the SSC PLC through relays and through a serial
communication line.
Control loops
The following closed loops are controlled by the
speed governor:
• Speed - Controlled by means of fuel rack
movement (actuator output). Speed is based on
speed reference - a 4-20mA input signal if
analog speed control is selected or; In case of
digital speed control, by digital inputs
"Increase speed" and "Decrease speed"
- Speed can be control in four different dynamic
settings based on status of the digital inputs
"Clutch 1" and "Clutch 2"
- Speed control is based on either droop mode
or isochronous mode (selectable)
• Charge air pressure - Controlled by adjusting
wastegate position. Set point based on BMEP
and speed. In case of failure maximum air will
be applied.
• NOx - Controlled by adjusting charge air
pressure reference or temperature reference.
Set point is based on BMEP. In case of failure to
NOx sensor bias is disabled.
• Temperature before turbine - controlled by
adjusting bias to charge air pressure control.
Set point based on BMEP and speed. In case of
failure to temperature sensor bias is disabled.
Open loop control
The following are controlled by open loops:
• Gas pressure - Controlled by 4-20mA signal to
main gas pressure control valve. Set point based
on BMEP and speed.
• Throttle position - Controlled by 4-20mA signal
to position actuator control. Set point based on
BMEP and speed. Position feedback to verify
position. Fail safe to open throttle.
• Prechamber gas pressure - Controlled by
4-20mA signal to prechamber pressure control
valve. Set point based on manifold air pressure
and speed.
• Ignition timing - Controlled by 4-20mA to
CPU95 ignition system. Set point based on
BMEP and speed.
• VVT - (Only applicable to C type engines) con-
trolled by digital 24VDC signal to solenoid valve.
On/Off signal based on BMEP with charge air
pressure as back-up. Fail safe position is Miller.
Engine is started in Miller. Position feedback
sensors for both positions for error detection.
Fuel rack limits
The fuel rack movement can be limited based on the
following conditions:
• Measured Lambda - In case of too rich mixture
engine fuel rack position will be reduced.
• Estimated Lambda - Value based on measured
gas pressure, air pressure and measured throttle
position. In case of too rich mixture engine fuel
rack position will be reduced.
• Torque limit - In case of too high torque engine
fuel rack position will be reduced.
• Gas flow limit - Value based on measured gas
flow (if available). In case of too high gas flow to
engine, fuel rack position will be reduced.
Monitoring System
The monitoring system consists of a PLC and I/O
modules connected trough a Profinet ring structure
collecting engine data to be displayed
locally and remotely on the alarm management
system. The monitoring system will also interface
the SSC and Safety system so that vital information
about the state of the engine control can be visible
to the operator.
The local interface consists typically of a 6" or 10"
touch screen interface. The interface consists of
several pages of process data, alarm information,
diagnostic messages and trends. The operator can
switch between the different pages trough the use
of buttons on the touch panel.
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