Gas Plant Condition Monitoring System
BJH Controls was contracted for the design, construction and configuration of a state of the art Rockwell Automation Condition Monitoring System for a multi-national Australian based company, requiring installation to connect with twenty four velocity sensors mounted to monitor the inlet cooling fan drive assemblies in a gas plant on the sub-continent. The panel, hardware and software required programming and logic to receive and process field inputs of vibration measurements and interface with a Plant Shutdown System (PSS) and Plant Control System (PCS).
Using the Rockwell Automation XM Online Protection and Condition Monitoring System for the project, BJH Controls implemented a protocol conversion gateway to allow the condition monitoring panel to communicate with the Plant Control System.
This system is based on using the XM-121 low frequency 2 channel modules, monitoring a total of 24 vibration inputs from the Velocity sensors, plus an additional two XM-121 modules for four spare inputs. Each XM-121 module is be accompanied by a XM-441 relay module providing two required relays, however this offers a total of five relays per XM-121/XM-441 combination.
The system comprises a monitoring/protection system that interfaces to both the primary shutdown system (PSS) and the primary control system (PCS). The interface to the primary shutdown system will be via hard wired relays (Fail Safe) and the interface to the primary control system is via the Modbus RTU bridge. Vibration, Alarm and Relay state data is presented to the Modbus RTU network in standard I/O format, i.e. Overall Vibration 32bit Float/Real, Alarms 3bit Binary and Relay state 1bit.
All the XM-121 modules process the signals and produce alarms (change of state) when set alarm thresholds are breached. When an alarm threshold is breached the modules send out a change of state message which can activate a relay in the XM-121 module and or the accompanied XM-441 expansion relay module. The radial vibration signals are also available via buffered outputs, by-passing the XM-121 A/D converter, for acquisition by hand held data collectors.
Power supplies are configured to be paired in parallel and utilise a decouple module as a preferred method of achieving redundant power supply. A separate power supply is employed to service the local HMI only.
The Field input terminal strip provides a location to land Common, Signal and Shield wiring from the 24 velocity sensors, plus four additional future sensors. The Output terminal strip has been allocated to wire the relay trip contact and common for 24 contacts, plus an additional two contacts.
The successful completion of a project such as this assignment required the implementation of effective project management practices. This was implemented through the direction of the BJH Controls standard Project Management activities.