Electrical installations must be designed with an emergency power system to generate and distribute electricity to a range of safety-critical consumers if the main power fails. Traditionally, electrical installations have been designed with a dedicated emergency power system that is independent of the main power system.

Some electrical installations are designed such that the emergency power source and/or emergency power distribution are an integral part of the electrical installation. A facility without a dedicated emergency power system will typically be designed so that the electrical installation is segregated into a number of redundancy zones that operate independently.

We have noticed that the industry is increasingly pushing the boundaries of the present regulations in terms of emergency electrical power system design, and accordingly wanted to obtain more knowledge and experience of established and newer solutions in this area.

The work was performed as an in-depth study with the consulting assistance of Unitech Power Systems.

The study resulted in a relatively detailed insight into the design of electrical installations without dedicated emergency power systems on three facilities with different characteristics.

This work allowed the strengths and weaknesses of the systems' designs to be identified and evaluated against a traditional installation with a dedicated emergency power system. 

The assessments covered technical, organisational and operational factors.

The report is available in Norwegian only.