Bergen B35:40, Project Manual

Page: 69 / 74

Safety, Control and Monitoring System
Page 6 : 9
3.02
, Gas
0211 BC
Design
As stated in the previous section the topology
chosen is a ring structure. Both the monitoring I/O
stations and the SSC stations are located on the
same physical medium (the same ring) but they do
not interfere with each other as the structure of the
Profinet is dedicated Master Slave relations. The data
from the monitoring stations are routed to the
Monitoring PLC while the data from the SSC stations
are routed to the SSC PLC.
If a sensor fault should occur on the monitoring
system this will be signalled to the alarm manage-
ment system; and if the sensor is duplicated on a SSC
station this signal will be available for the operator.
The operator now knows that the sensor for the
monitoring system has malfunctioned but is still
able to see the process value. This will also work the
other way around. If a sensor fails to the SSC system,
it will be signalled to the alarm management system
that a SSC sensor has malfunctioned.
Process values from the SSC system can be moni-
tored on the operator panel as such signals can be
made available to the operator through the Profinet
field bus. Such values can be rack/load deviation and
data from the speed governor indicating the behav-
iour of the engine.
Client communication
Communication to IAS or alarm management sys-
tems is usually done using a serial RS485 Modbus
RTU link. Available on this link is process data from
the engine as well as status and alarm information
initiated by the engine control system.
Back-up instrumentation
The back-up instrumentation consists of two
analog indicators (engine speed and lubrication oil
pressure), which are considered the absolute mini-
mum for operation of the engine in an emergency
situation when the engine has to be operated
manually and the graphical display fails.
The engine speed indicator signal is driven by the
Safety PLC. The lubrication oil pressure indicator
signal is driven by a separate transmitter.
Back-up instrumentation incl. graphical display
24V distribution cabinet
RREB delivers a 24V distribution cabinet.
There are 2 alternatives:
Alt1: Main 230V/24V DC with back-up 24V/24V DC
Alt 2: Main 230V/24V DC with back-up 230V/24V DC
The drawing C 976/57 below shows alt 1.
The cabinet will:
•
Secure stable redundant 24 Voltage DC to
RRMEB´s electrical equipment.
• Separate RREB´s electrical equipment
galvanically from the 24 Voltage DC on board.