A number of incidents have been reported to Insjö/Foresea in which sensitive electronic equipment has suffered from malfunctions. Sometimes this is a consequence of a black-out and on a couple of occasions, UPS failure (Uninterruptible Power Supply – an electrical apparatus which prevents disturbances in the power supply, such as frequency changes or power failure). There are many important instruments on a ship which are sensitive to changes in the power supply. In some cases, they may take a long time to start up again if they fail or shut down.
The Swedish Transport Agency comments as follows.
• UPS units require frequent testing and regular maintenance. Some do not alert when the batteries are discharged.
• If a UPS fails, it should be easy to make a bypass connection.
• UPS units are of different quality. Some are intended for office use, others for industrial and marine use. The quality required must be considered.
• If a UPS is overloaded it can cause disturbances to equipment connected to it. During maintenance, it should be checked that the capacity is not exceeded, especially if the installation has plug connections.
• If a UPS is used for navigation and safety equipment it should be permanently fitted and comply with electrical and environmental standards that are not lower than that of the connected equipment.
Insjö/ForeSea id 1370, 1451, 1585, 1773, 2111, 2515