London Underground 4LM HSCC ACO


ISS were tasked with the design of an Auto Changeover (ACO) System for the London Underground at the new Hammersmith Service Control Centre (HSCC).

The existing manual system was removed, with the Auto changeover system being implemented to automatically execute the switching process in the event of any supply failures. Involved within these works was the design, manufacture, testing and commissioning of the Automatic Changeover Panel which also included the implementation of a Cable Management System (CMS).

The changeover system uses an intelligent controller to select available supplies and automatically changeover, with time delays where applicable, to select the appropriate supply. The ACO system is an integral part of the HSCC building and helps deliver power to critical areas within the building, including the signal control centre to help ensure the tubes are running seamlessly.

As a requirement of the contract award, ISS were tasked to create a Conceptual Design Specification (CDS) based on the requirements of the control centre. As part of the conceptual design, ISS gave numerous presentation to multi-disciplined engineers within the London Underground (LU) team. ISS were instructed to provide a robust design which minimised any potential risks for the end user. Through this, ISS had to show evidence of how these were omitted through deign risk assessments and design management plans, ensuring LU standards where strictly adhered to.

A key factor for this project was health and safety. The Hammersmith site had been presented with a Beacon Award, which ISS continued to help maintain this prestigious health and safety award.

ISS performed a factory acceptance test (FAT) within our in house test facility which was attended by LU Engineers. Before the FAT, ISS designed a ‘simulation model’ which would simulate all possible scenarios that could occur on the existing Hammersmith electrical system. Due to the HSCC ACO project being unique, ISS had to create new control test sheets and documentation to cover all eventual scenarios to implement and develop a robust product.

Upon installation and commissioning of the ACO system, ISS performed a site acceptance test (SAT) which was accepted by all involved. ISS then commissioned the ACO into service and completed a handover of all documentation back to the client.