top of page

Colchester Hospital's Green Transformation: Upgrading to a Safer, More Reliable Power Network

Colchester Hospital - Case Study


The Colchester NHS site wished to upgrade their existing 11kV network due to obsolete equipment. It was important for the client to operate the network using environmentally friendly and safer equipment. Previously, the site was operating on 1000kVA oil transformers and oil circuit breakers. To fulfil the client’s objective, East Solutions would supply and install two new Tier 2 Midel transformers and three custom-made vacuum circuit breakers, into the existing HV switch board. Midel transformers are known for their biodegradable and fire-resistant insulating fluid and vacuum breakers for their technology.

The upgrade works would provide Colchester hospital with a more environmentally friendly and safer power network, while improving its reliability and efficiency.

 Project Facts    


Ensuring that the project was built to the required specifications and standards, East Solutions in-house Technical Department completed a full set of CAD drawings and provided the client with essential manufacturer recommended components prior to the project kicking off on site.

The site went through several phases to update and improve the equipment. The existing transformers and circuit breakers were disconnected and disposed of properly. East Solutions installed two package substations with new transformers and replaced three old oil circuit breakers with vacuum circuit breakers. In order to accommodate additional auxiliary signals, a new multi-way secondary connection pin board was installed on the retrofit circuit breakers. Safety was a priority for the hospital, so an electronic close/trip lanyard feature was added for safe local operation of the equipment. To improve the accuracy and responsiveness of the protection system, the existing IDMT protection relay were replaced with new electronic relays. Ensuring that the equipment was still functional after the retrofit process, new terminal blocks were installed to accommodate existing LV intertripping and Emergency Power Off buttons. Finally, status indication LEDs were installed to provide the client with immediate visual aids for the status of the equipment. The LEDs also allowed for connection to the existing BMS system, which would enable remote status viewing in the event of troubleshooting.

East Solutions carried out full intrusive maintenance and rust touch-up during the replacement program, as well as accommodating a training session for the site APs to understand the operation and functionality of the new equipment. Prior to handing the project back to the hospital, a commissioning team was deployed to ensure the equipment was tested, worked and met the required standard prior to energisation.

To track key milestones, timelines, and deliverable as well as ensuring regular communication and collaboration between the manufacturer, design team and client, a dedicated project manager and coordinator was assigned to the project.


Upgrading the site within the confinement of the existing substation posed several challenges for the team. The limited space available for the installation of new equipment and the expansion of existing infrastructure meant it was difficult to accommodate new components required for the upgrade. Working within a limited space also meant extra safety measures needed to be put in place for the work to be carried out safely.

The shutdown of supplies at the hospital required careful planning, coordination, and communication with multiple parties. East Solutions liaised closely with both the DNO and the hospital’s AP to plan the shutdown and ensure that all necessary backup generation was available. The shutdown was meticulously planned to coincide with the hospitals quiet periods and coordinated with the operating theatre schedule to minimise the risk of any disruption to critical procedures.

 The Results 

The upgrades carried out at Colchester hospital have resulted in significant benefits in terms of improved technology, reduced maintenance, and improved health and safety. This will help the hospital to continue to provide high-quality care to its patients while also promoting environmental sustainability.


bottom of page