Power supply requirements
GMDSS equipment is required to be powered from three sources of supply:
- ship's normal alternators/generators;
- ship's emergency alternator/generator (if fitted); and
- a dedicated radio battery supply.
The batteries are required to have a capacity to power the equipment for 1 hour on ships with an emergency generator, and 6 hours on ships not fitted with an emergency generator.
The batteries must be charged by an automatic charger, which is also required to be powered from the main and emergency generators.
Changeover from AC to battery supply must be automatic, and effected in such a way that any any data held by the equipment is not corrupted (ie: "no break").