West London NHS Trust

During planned testing of the in house emergency standby generator system, a number of critical items of medical equipment had experienced failures which resulted in a risk to both security and to patient care within the medium secure buildings.

E-Sine Ltd were approached directly by the senior estates management team for their reputation and experience in resolving of power quality and integrity problems.

E-Sine Ltd were appointed to undertake a detailed analysis of the electrical infrastructure and the quality of the supply during transition between mains and emergency power sources to enable a clear understanding and identification of any faults or adverse conditions which could be responsible for the failure of medical equipment.

A comprehensive evaluation of the high and low voltage main electrical infrastructure and associated distribution and switchgear systems was undertaken. This allowed for production of accurate record drawings and with a clear understanding on HTM compliance as well as strategic basis for identification of key points in the system to install multiple portable power analyser’s.

The main challenge on this project was in undertaking any works due to the system being live and with limited opportunities to de-energise the electrical system due to the critical medical load.

These were overcome with careful planning and preparation such that all works requiring access directly onto the electrical system were coordinated to occur during a short window under pre planned mains generator testing events.

E-Sine Ltd have a collective experience of over 20 years for designing, managing and implementing power quality solutions within critical healthcare services applications.

In addition, E-Sine engineers have been contributors to the 2017 rewrite of the Health Technical Memorandum documents, specifically in providing advice and information relating to robust and resilient electrical infrastructure design for the most critical patient areas. This knowledge provides a comprehensive foundation for understanding the reasons which can cause spurious problems within electrical networks which can effect sensitive medical equipment such as in the case of this project.

The results of the power assessment revealed a number of potential issues including a high transient voltage which became present during a 4Pole changeover event between mains and generator sources which is typical of a lacking neutral to earth link system.

A remedial works package involving the upgrade of the dedicated neutral to earth system was designed, implemented and managed by E-sine under a permit to work and safety programme event in order to provide stabilisation to the electrical system.

A repeat power analysis exercise was scheduled and managed by E-sine which demonstrated the transient neutral to earth voltage spike seen during previous mains to generator testing had been resolved.

A separate power related event was also captured during the power analysis survey which identified a significant transient current event which occurred periodically and without pattern. E-Sine undertook further inspection which resulted in the discovery of a failing main switchboard. This was subsequently repaired and prevented a significant failure which could have led to an extended loss of power to key medical areas.

A report on the power quality for the electrical infrastructure together with findings and recommendations was prepared and published for client information and further actions.