General Classification Rules

All marine engines shall have type approval certificate, i.e. the engine design is approved through a thorough type approval scheme. For engines used for main function or emergency duty and power 300 kW or above shall have product certificates issued by classification society. For engines with rated power below 300 kW and engines, that are not used for main function or emergency duty manufacturer’s product declaration is sufficient. The same requirements as described in the chapter for main engines applies for auxiliary diesel engines as well, excluding the specific requirements for propulsion engines. The rules for instrumentation of auxiliary engines are slightly different from the ones used for propulsion engines and can be found from DNV-RU-SHIP Pt.4 Ch.3 Sec.1.5.5 Table 11. //DNV-RU-SHIP Pt.4 Ch.3 Sec.1 and Pt.4 Ch.3 Sec.1.5

The main electric power supply system shall have the capacity to supply power to all services necessary for maintaining the ship in normal operational and habitable conditions without using an emergency source of power. Normal services typically include propulsion machin-ery, steering gears, safe navigation, fire and flooding safety, internal and external communications and signals, means of escape, emergency lifeboat winches, anchor winches, lighting necessary to perform normal operation and maintenance tasks, and designed comfortable conditions for habitability, including cooking, heating, domestic refrigeration, mechanical ventilation, sanitary and fresh water. Thrusters (if not forming a part of main propulsion or steering), mooring, cargo handling, refrigerators for air conditioning, ballast water treatment system and exhaust gas cleaning systems are normally not considered as necessary services for normal operation. //DNV-RU-SHIP Pt.4 Ch.8 Sec.2

The redundancy for main sources of power shall be arranged such, that in case of any power source (engine/generator), transformer or power converter is out of operation the capacity is still sufficient to supply power for services necessary to provide normal operational condi-tions for propulsion and safety, ensuring minimum comfortable conditions of habitability (as listed above) and starting the largest essential or important electric motor on board (except auxiliary thrusters). Exceptions for redundancy and/or capacity can be made for non-SOLAS vessels. //DNV-RU-SHIP Pt.4 Ch.8 Sec.2
In vessels where the electrical power is necessary for propulsion and steering of the ship the power supply shall be arranged such that the required power will be maintained or immediately restored in case of loss any of the power sources in service. The power system shall be equipped with automatic load shedding or other automatic means to prevent sustained overload of any source of power. A load shedding shall be activated at load level suitably below 100 % of the rated current of the source of electric power. Overload protection may be arranged as load reduction or as the tripping of non-important consumers. Where several power units in parallel operation are required to cover the ship's power supply, the failure of one of the units shall cause the immediate trip of non-important equipment and, where necessary, the important equipment, where this is the only way to ensure that the remaining units can be kept in operation to permit propulsion and steering and to ensure safety.  //DNV-RU-SHIP Pt.4 Ch.8 Sec.2.2.2 and Pt.4 Ch.8 Sec.2.7.1