Bespoke Control Panel Build for a Bradford Plant Room

The brief

A commercial site in Bradford was upgrading the HVAC plant in the main mechanical room. The existing controls were a mix of standalone time clocks, relay logic on a back-of-board terminal rail, and three separate motor starters with no central interface. Maintenance was relying on tribal knowledge to keep the building comfortable. The client wanted a bespoke PLC and HMI control panel that ran the whole plant from one cabinet, with a touchscreen front face for the building manager and Modbus integration with the BMS for remote monitoring.

What we did

The job ran in three stages: design, build and install. The whole package came from one supplier so the client had a single point of accountability from spec to commissioning.

• Design and electrical drawings: Functional spec agreed with the M&E consultant and the building manager. Schematic and panel layout drawings issued for approval before any metalwork was ordered.
• Build in our workshop: Form 2 enclosure, IP54 rated, BS EN 61439 compliant build. Siemens S7-1200 PLC, KTP700 HMI touchscreen front face, soft-start motor starters on the larger fans, ABB inverters on the AHU fans for variable-speed control.
• Factory acceptance test (FAT): Every input and output bench-tested against the cause and effect document before the panel left the workshop. PLC code uploaded, HMI screens populated, operator simulation run through with the client signing off before delivery.
• Site install: Old controls stripped out over a weekend shutdown, new panel craned into position, all motor and field-device cables transferred across and re-terminated against the new schematic.
• BMS integration: Modbus RTU link between the new PLC and the existing BMS head-end commissioned and tested. Building manager now sees plant status, alarms and runtime hours from the BMS console.
• Site acceptance test (SAT): Full live cause and effect run on site, every alarm and interlock tested, operator handover documented. Manuals, drawings, PLC source code and SAT certificate handed over in the O&M file.

The result

A single, well-documented control panel running the entire plant room from one HMI, with proper visibility from the BMS. Maintenance no longer needs the tribal knowledge: the schematic, the PLC code and the cause and effect document tell the next engineer everything they need to know. The soft-start on the larger motors reduced the inrush current on the supply, and the inverters on the AHU fans dropped the plant electricity cost noticeably in the first quarter.

Spec: Form 2 IP54 enclosure, BS EN 61439 compliant, Siemens S7-1200 PLC, KTP700 HMI, soft-start starters and ABB inverters, Modbus RTU to BMS, full FAT and SAT, O&M file with PLC source code and drawings.

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