Victron inverter through transformer troubleshooting

[Downeaster]

I really couldn't be more confused. New (2012) boat to me - from Europe but 'converted' for U.S. electrical.

When I turn on the Victron MultiPlus Compact inverter I am seeing 115/120v AC between neutral and hot on a standard US-style 3-conductor plug. Makes sense.

BUT - I am also seeing 230V between the either neutral or hot (I am off the boat now and can't recall) and ground (3rd prong on bottom of US plug). That certainly does not make sense unless I'm missing something. That must mean 230V on one side and 115/120V on the other side to yield 115/120V between the two.

The inverter puts out 230V so I understand that. It is then connected to a Victron Autotransformer to step down to 120V which is what should end up at the receptacles.

Maybe the Autotransformer is tripped and being bypassed -- therefore 230 at the receptacles? It doesn't seem like it because the circuit breaker switches stay in the 'On' position. BUT I'm not sure... attached is a picture showing what they look like now. Do the red indicators mean a fault? Or is that just normal when they are on? I've looked at the CHINT (breaker manufacturer) docs and it really isn't clear at all.

So two questions, to summarize:
1. Easy one I hope: are the breakers ok? Or does the red indicator with the switch on mean they are failed? This vintage of the Autotransformer doesn't have LED indicators like the new ones.

2. Why am I seeing 120V between hot and neutral but 230V with ground?

I am being very careful with everything (and turning off the inverter) since it doesn't seem right.

Thanks to anyone who can give me a nudge in the right direction. I've done a lot of research and am really stumped....

[smac999]

Is this passing through shore power or inverting?

When inverting. The auto transformer should have a ground - neutral relay ingauged. The autotransformer can still put out 120 And 240. It will have 4 wires and 2 hot legs. So something could be wired wrong. Bringing 2 hots to a plug.

They may have only used 3 wires but then you are limited in amps as the transformer wants to be balanced.

You get normal 240v readings from the isotransformer of 120 from each line to neutral, 240 line to line and ground and 0v n-g.

When on shore you kinda end up with a sorta floating ground as the n-g relay in autotransformer will open if wired per victron. And you may get some strange voltage readings.

Realistically you are going to have to follow the wires and voltage from the auto transformer to the outlet to know what’s going on.


Is the shore going through a isotransformer before it goes to the 230v inverter? It really should be. As you would want 230v hot to neutreal going. Into the inverter.

[Downeaster]

Originally Posted by smac999

Is this passing through shore power or inverting?

When inverting. The auto transformer should have a ground - neutral relay ingauged. The autotransformer can still put out 120 And 240. It will have 4 wires and 2 hot legs. So something could be wired wrong. Bringing 2 hots to a plug.

They may have only used 3 wires but then you are limited in amps as the transformer wants to be balanced.

You get normal 240v readings from the isotransformer of 120 from each line to neutral, 240 line to line and ground and 0v n-g.

When on shore you kinda end up with a sorta floating ground as the n-g relay in autotransformer will open if wired per victron. And you may get some strange voltage readings.

Realistically you are going to have to follow the wires and voltage from the auto transformer to the outlet to know what’s going on.


Is the shore going through a isotransformer before it goes to the 230v inverter? It really should be. As you would want 230v hot to neutreal going. Into the inverter.

Thank you, Smac. Very helpful. This is inverting off the batteries. I will follow the wires but your hypothesis that two transformer hots are wired (incorrectly) to the single distributed hot makes sense. How else would I see 230v?

Anyone have any thoughts on the 'red' indicators on the transformer (picture above)? Why would 'on' be red? I would think it would be green.