Pump room control panels for a 17-generator data centre fuel system

The requirement

Keep the day tanks of 17 standby generators full from four underground bulk tanks, on HVO fuel. The contractor had replaced the pressurised ring main in the original specification with a low-pressure system that runs only on demand, to keep the risk of a leak down: submersible lift pumps and booster pumps start when the generators call for fuel, one pump serves up to nine generators, and a second starts beyond that. If a pump does not prove flow within ten seconds, the next one takes over. A generator fire dumps that generator's fuel by gravity to a dump tank, which pumps itself back to the bulk tanks once it passes 85%. The controls had to make all of that work, and keep working if either pump room is lost.

The constraints

• Two pump rooms, with control handed to the other room if one has a fire.
• Pumps fed through changeover panels, so either pump room's supply can run them and one room can be isolated.
• Generators across several floors of generator garages, each shown on the door, with every pump and motorised valve controllable by hand if needed.
• A design that changed as the contractor and the consultant worked through it: the pump room drawing set reached revision 13, the last change adding valve control from two locations.

What we built

A floor-standing PLC panel for each pump room, with Siemens S7-1200 controllers on a Siemens media redundancy (MRP) ring network, a touchscreen HMI and a full mimic on the door: generator demand lamps floor by floor, running, flow proved and fault lamps with hand/off/auto for each pump, open and closed lamps with open/close/auto for each motorised valve, and fire, emergency stop and supply healthy indication. Four changeover panels feed the bulk tank pumps from either pump room's supply. A fill point PLC panel runs the tanker fill point and the four bulk tank return valves, with common leakage indication. We wrote the PLC and HMI software.

Delivery

The seven panels left Stoke-on-Trent in batches between mid-March and mid-April 2026, each with its drawings and test certificate.

The outcome

A fuel system whose controls were designed, built and programmed by one company, and that keeps fuelling the generators with a pump room out of action. It is the fourth generator fuel system we have built for this contractor since 2024, three of them for data centres: before it came a generator compound with duplicated master panels so the fuel system stays concurrently maintainable, and a multi-storey data centre with separate fuel and AdBlue systems across four floors, thirteen panels in all.