A very wide range of uninterruptible power supplies (UPSs) is in use in the offshore marine sector. IMCA has produced this guidance to assist its members in aspects of their design, selection, installation and use.

Information provided by IMCA members shows that most of these units are of commercial grade and of the 'online' type, i.e. where the inverter continuously supplies the load. There is a wide variation in the cost, quality and capability of UPSs and purchasers should carefully consider and understand the required application and the electrical and environmental conditions in which the UPS or DC power supply will be expected to operate. Features and levels of performance cannot be taken for granted and standards for UPS design assume that much of the specification for performance will be agreed between the purchasers and the supplier. Therefore, simply making reference to a particular standard in a specification document does not necessarily guarantee the unit will be fit for purpose. In addition to poor choice of equipment for particular applications, the information provided revealed that premature battery failure is a key issue in UPS reliability and maintainability.

Thus the guidance provided concentrates heavily on the maintenance and testing of batteries and on the advantages and disadvantages of different battery types.