During an overload, the power loss in the conductor rises with the load squared, and the temperature also rises according to Equation
ΔT˚C = K × (watts)0.8
Overloading ship electrical equipment above the rated temperature limit reduces life to about ½ for every 10°C rise above the design temperature.
This 10°C rule for half-life is based on typical properties of ship insulation’s normally used in electrical machines. Experience on other ship electrical components, such as ship power electronics devices, suggest a different rule, such as every 7°C rise for reducing the life to one-half.
Ship cable overload problem
This a significant reduction of life, that continuous overload, even by 10%–15%, is not economical. That is why 15% overload on electrical
equipment is limited to an hour or two, and that also only on occasion.
