The boat has a pair of Quattro 24/5000/120 configured to switch as a pair. A pair was used for size and capacity requirements as well as the need to supply both 110VAC and 220VAC loads on the boat. For the pair to switch over to shore power they need 110VAC 180 degrees out of phase, 220VAC line to line with a center tap neutral. That is normal USA based home service. The pair always switched over when docked in the USA at home. Shore power at marina’s can be anywhere from 200VAC to 250VAC. The voltage range isn’t the problem. However, sometimes there isn’t a neutral or the power is three phase and the phase angle is 120 degrees or the breaker is a ground fault style and trips.
To solve the mis-match and give the boat the ability to accept most all shore powers, isolation transformers were installed between the shore power plug and the quattro pair. A pair of 4500 Watt 220VAC to 110VAC transformers where installed, one for each of the quattros. The 220VAC input eliminates the need for a shore power neutral. The isolation transformers allow to seperate boat ground from shore ground and eliminate ground fault breaker trips. To always create power that is 180 degrees out of phase it is required to switch the incoming feeds to the transformers. L1 shore to L1 transformer1 - L2 shore to L2 transformer1 on one and L1 shore to L2 transformer2 - L2 shore to L1 transformer2 on the other. On the output side of the transformers tie the output neutrals together to get 110VAC supply for the quattros.
