Problem

When a Northeast generating station began experiencing periodic failures of key components in its Duct Burner Management System (BMS), station personnel found that much of the core components, including the PLC, HMI and Network, were obsolete. While factory-repair was an option, it did not allow for an immediate turnaround or an inventory of critical spare parts.
 

Solution

TSI Turtle Services (TSI) proposed a migration strategy for upgrading the obsolete core components of the control architecture, including the PLC Control Architecture, HMI System and Network Architecture. The challenges included (1) not disrupting the existing field device architecture or the wiring infrastructure, and (2) moving the panel inside and out of the weather.
 

Implementation

TSI chose the Rockwell Automation ControlLogix PLC system with redundant controllers, an IO Chassis, new HMI panel, and a gateway system that are all connected over a resilient device level ring Ethernet network. This means that each device has two Ethernet connections to the network, enhancing system reliability.
 
The control system communicates to a Honeywell DCS system using a Modbus gateway device. This allows communication of the Rockwell Automation PLC to the ABB Distributed Control Systems DCS using the Modbus protocol. The PLC is connected to the gateway device over Ethernet and to the DCS by Modbus Serial connection. Both reads and writes were performed between the DCS and Control system to allow local or remote operation of the system.
 
By using the Rockwell Automation PLC5 to Control Logix Wiring conversion system, field wiring remained intact. Existing wiring and field wire conversion modules were used instead of manually rewiring the system. This reduced downtime and expedited the field installation. In addition, all the existing wiring documentation could be used in support of the system.
All new equipment and components fit into the same footprint as the old system except for a new wall-mounted enclosure that was moved inside the facility to eliminate a history of HMI failure due to inclement weather.

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