Voltage Safety: High or Low?

Legislators and ship operators are continually seeking cleaner ship operations. One route to achieving this is through some form of electric propulsion, which, when coupled to energy storage systems, can realise the goal of zero-emission operation. With electric propulsion, the propulsion load, in whole or in part, becomes another consumer to be supplied by the ship’s electric power generation and distribution systems.

This leads to a considerable increase in the electrical power that must be generated and managed. As every ALevel student knows, power is the product of voltage and current. Any increase in the power generated must be achieved by an increase in voltage, or current, or both. To increase the current leads to greatly increased heating and requires heavier conductors, so the preferred option is to increase the voltage.

This raises the question of safety. There is a perception that high voltage (HV) systems are inherently ‘more dangerous’ than low voltage (LV) ones, but the Authors contend that it is meaningless to argue that one system is ‘less safe’ than the other since LV can kill just as effectively as HV. The real issue is that the practicalities and safety implications of HV and LV systems are different, although there are some points in common.

In this paper we shall review the hazards and safety implications peculiar to HV and to LV, and those common to both. In the process we shall review operational practices and how they apply to HV and LV systems on board current platforms. Finally, we shall examine whether there is any transfer between LV and HV concluding on how best practice can be applied to future platforms to provide a greater assurance of safety at system level.