Keeping warm in the January sales

End User: Large Retail Premises

Location: West London

The heating and ventilation (HVAC) for this large historic building is currently being brought in the 21st century by one of our clients. The heating for the AHU's is provided by a hot water system in conjunction with five 1MW steam heat exchangers. Previously these heat exchangers had individual stand alone control systems. 

The new integrated PLC control system allows the heat exchangers to be intelligently controlled, reducing energy usage and providing a more stable heat source. The system was supplied with a small HMI in order to allow the FM team to diagnose issues with the system and integrated with the BMS system in order to allow remote operation.

The system has breathed new life into existing plant for minimal cost.

Process control - a new start

End User: Animal Feed Producer

Location: Cambridgeshire

Having been producing animal feed pellets from straw for the last 25 years, this plant underwent a major refit in the summer of 2008. The existing control system was installed in the 1970's and was largely relay logic with a large mimic diagram of the plant.

The new control panels are now PLC controlled and the operators use touch screen HMI's to drive the plant. The extensive trending of process values has provided fresh insights into the operation of the plant. Using this new found knowledge and additional control loops has increased production and decreased energy usage with the same mechanical plant. Further energy savings have been made by automatically putting unused parts of the plant to sleep.

The safety of the plant was improved with increased guarding and programmable safety controls for the many zones in the facility. The safety system reports directly to the PLC and allows the status of the interlocks to be reported on the HMI, leading to reduced downtime.

The reconfigurable building

End User: Major International Financial Institution

Location: City of London

Building on an innovative design from the client's consultants, new LV Distribution and UPS's were installed in this large London site with minimal downtime. Several parts of the remaining infrastructure posed unusual challenges in controlling the LV power. A Triple redundant PLC control system (sometimes referred to as Triplex) was installed as part of the project. This control system routed the power around pinch points in the building allowing the supply to be maintained whatever the failure scenario.

The control system is installed on multiple floors and configured in such a way as to provide no single points of failure. The generators, LV distribution and load shedding are all controlled from the new system. Operator control touch screens are provided at multiple locations in the building to allow the FM team total visibility of the critical power distribution in the building.

Critical power with the Penguins

End User: Ministry of Defence

Location: South Atlantic

As the infrastructure in these three critical remote sites had reached the end of its life, a project was undertaken to provide new power supplies. The power was provided by 4 LV generators which operated in a 2N configuration. A Triple Channel PLC control system (sometimes referred to as Triplex) was supplied to control the generators and LV load shedding automatically. This control system was designed to have "No Single Points of failure"

When the power demand was low the system automatically sheds a generator in order reduce site fuel consumption. In times of heavy demand (or conflict) two generators are run to provide the necessary security of power for these crucial sites. Duty rotation of the generators is also taken care of by the control system.

Full diagnostics and control of the system is achieved from HMI's located in the LV switch room and the living accommodation - a vital feature when the winter weather features high winds and deep snow.

And the penguins? Once the system was operational with a resilient multi-channel design keeping the lights on, there was time for a little site seeing.

Load Shedding - A zero downtime retrofit installation

End User: Major UK Bank

Location: City of London

A major revamp of the load shedding was needed in this building, due to the current building load far exceeding the original design criteria. The existing system was in situ and was controlling the majority of the LV breakers in the building. The incumbent system was not being well supported by the original supplier and the client wanted a change of control philosophy as well as a greater flexibility.

A design was proposed whereby a new load shedding system would be installed "over the top" of the existing system, with the option to switch back if necessary. The new system was installed out of normal working hours on custom back plates mounted on the doors of the existing PLC enclosures. The control of the breakers was migrated one at a time form the old system to the new.

The new system is an Active Load Control system which measures the current building loads and manages the connected loads in order to maximise building availability in the case of a power failure. The priority of the loads is set by the user from a large HMI, which also show the status of the controlled loads and all system diagnostics.

A series of fall back scenarios are implemented that allow the system to continue to operate even in the event of a failure of the power monitoring. This system has enabled this critical building to be operational until the fundamental issues of building load can be addressed.