The boat AC system shown in this posting was designed by a highly experienced, qualified Victron designer. The highly qualified, local Victron supplier and the very experienced ABYC electrician who will install the system do not agree with the design. As can be seen below on Sheets 1 and 2, there are two 120/240v shore power feeds with each one supplying Input #1 of a Quattro. The 48/8000 Quattros are to be set for parallel operation, 60Hz, and 240v Out. On Sheet 3, the Output #1’s of each Quattro are interconnected and feed a 100a autotransformer. That autotransformer supplies all 120v and 240v to the boat.
The supplier and electrician are concerned that this design is not safe. If the two shore power outlets are not wired the same, they contend it would result in a short circuit, major failure, or other serious problems. They say that 2 shore power supplies should not be interconnected in any way. They contend that 2 shore power supplies must only feed 2 independent load center. The system designer designer contends that the system is safe since any unsafe connections are prevented by the Quattros.
Which position is correct? Is the design safe, as shown? Should it be modified? Does this design conform to accepted standards, such as ABYC?
They are right, the construction is not safe, but could be made safe with an aditional relais before the second quattro with a small unit that checks if the inputs are in phase and then swich on the relais.
The other possibility would be to split the whole thing into two chargers feeding the 48v battery, 2 parallel inverters feeding the boats 117/230 ac circuits.
See Sheet #3: What if the interconnection of the Output #1’s is eliminated? Then have Quattro #1 still connected to the Autotransformer so that the L1 and L2 120v loads are balanced. Quattro #2 would mainly handle 240v loads. And, STILL HAVE BOTH QUATTROS CONNECTED TO THE SAME BATTERY BANK. It would not be a parallel system, but seems better than having 2 house battery banks. Would this work?
Would the 2 Quattros still be set up as being in parallel so that they are still acting in parallel to charge the batteries?
Since there would be no interconnection between Shore 1 and Share 2, It is expected that solves the interconnection safety concern. Any other safety concerns?
