250kVA Rooftop Standby Power for the National Centre for a Children’s NHS Hospital

Project scope

The solution centred around a bespoke 250kVA canopied generator, powered by a Cummins diesel engine and coupled with a Leroy-Somer alternator.

Due to its rooftop location, the generator was designed around a number of site-specific considerations.

Acoustic performance was particularly important. CPS engineered the super silence soundproof canopy to achieve a maximum noise level of 75dBA at 1 metre, helping minimise the impact of the generator within the surrounding healthcare environment.

The generator was controlled by a Deep Sea Electronics DSE7320 MKII controller, with a DSE2157 expansion module incorporated to enable integration with the site’s wider management system.

Additional features included a water jacket heater, anti-condensation heater, internal bunded fuel arrangement and fire shut-off valve.

With the complete generator positioned at roof level, weight distribution and structural loading also played an important role in the design. A specialist Big Foot support system was incorporated to distribute the equipment load effectively across the available rooftop area.

Lightning protection was another key requirement. The generator and associated installation were designed to integrate with the building’s lightning protection system while maintaining the required clearances and protection around the equipment.
CPS produced bespoke design documentation and 3D GA drawings to ensure the footprint, access requirements and serviceability of the generator were fully considered before manufacture.

Future maintenance access was also factored into the design, ensuring the equipment could be safely inspected and serviced throughout its operational life.

Once manufactured, the generator underwent Factory Acceptance Testing, witnessed by representatives from the M&E contractor and NHS.
Following installation, CPS completed a comprehensive Site Acceptance Test and commissioning process.

This included full load testing and a complete black building test, simulating an actual loss of mains power to prove the performance of the standby system under real operating conditions.

A key performance requirement was for the generator to start and provide the required standby power within 15 seconds of mains failure.

The system performed as designed, successfully demonstrating the automatic response and integration required to protect the facility’s selected life safety systems.

Following testing, the generator was successfully commissioned and handed over first time.

Challenges
Installing a bespoke standby generator on the roof of a healthcare facility presented a very different set of considerations to a conventional ground-level installation.

The available rooftop footprint had to be carefully assessed alongside the overall generator weight, structural loading and future maintenance requirements.

The Big Foot support system provided an effective solution for distributing the generator load while maintaining a practical and compact installation.

The CPS engineering team also had to consider how the generator would integrate with the building’s existing lightning protection system without compromising either the installation or the protection requirements of the facility.
Acoustics added another layer of complexity.

With the generator located within a healthcare environment, sound levels could not exceed 75dBA at 1 metre. The enclosure, attenuation and super silencer arrangement were therefore designed specifically around the site requirements to provide the necessary performance without compromising ventilation or generator operation.

Despite the combination of rooftop restrictions, acoustic requirements and specialist electrical integration, commissioning progressed smoothly with no unexpected issues.

The successful black building test provided the final confirmation that the system would respond correctly during a genuine mains failure.

Aftercare
Following successful commissioning, CPS provided a complete operational handover to the client team.
Training covered generator operation, weekly and monthly checks, fault conditions and the procedures required to identify and resolve common alarms or failures.

A complete O&M manual package was also provided as part of the final handover documentation, giving the client the technical information required to operate and manage the system with confidence.

The response to the completed installation was extremely positive, with the client particularly impressed by the commissioning process and the time taken by the CPS team to provide reassurance, answer questions and demonstrate the capability of the equipment on site.

The successful delivery has already generated discussions around several potential future projects.
For the CPS team, this was also a particularly meaningful project.

The NHS Children’s Hospital is a major new healthcare facility in Sheffield, close to our Yorkshire base and dedicated to improving children’s healthcare through technology and research.

As a team with families of our own, it is one of those projects that carries additional significance.
It also demonstrates the breadth of CPS’s healthcare capability. From bespoke engineering and rooftop installations to acoustic performance, testing, commissioning and client support, every element was designed around one objective: providing dependable standby power for a critical NHS facility.

Another successfully delivered healthcare project and another example of CPS providing the technical expertise, quality of manufacture and service required for critical power infrastructure.

The UK’s Trusted Critical Power Partner.
Get in touch if you would like to discuss a healthcare standby power or critical power project with our team of experts.

📞 01757 428140
✉️ info@cps-generators.com