In marine field, above 1000V (>1000V) is considered as high voltage (HV) and below or equal to which is low voltage(LV). High voltage system are normally used where there is a high electrical power demand such as electric propulsion, bow thrusters etc . Benefits of this system is related to Ohms law, for a given power, current gets reduced as the voltage is increased.
Advantage Of High Voltage System (Why High Voltage Systems Used)
> Overall System size and weight get reduced compared to same power low voltage system
> Reduced space means more cargo space and profit
> Conductor size gets reduced because of low current, which means reduced copper resulting in low cost.
> Copper loss= I^2. R; less current therefore less copper loss
> Easy installation
> Due to the electric propulsion there is more control on navigation and engine room size get reduced.
Disadvantage Of High Voltage System
> Main disadvantage perceived by the user is, when working on HV installation, its very necessary to adhere to stringent safety procedures
> High voltage leads to high risk
> Danger of arcing
> Skilled personals required
> Special switches are required
What Are The Additional Safeties On High Voltage System?
> Main safeties are its special breakers. HV circuit breakers either air, gas or vacuum breakers.
> To minimize the size of earth fault current, neutral earthing resistor is using in HV system.
> Better insulating material like Micalastic is used.
> HV equipment are well designed to have an insulation life of 20 years
> Special relays are provided for overall circuit protection of HV circuit
> Earthing down is essential for HV maintenance which should be declared in Electrical Permit to Work.
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