Steve wrote:
I would like to wire up the inverter on my boat to be very simple to
switch on and connect into the boats mains wiring. Ideally I want just
one switch. I am happy for this to be a big battery switch. I want the
plugs and other mains appliances (microwave, some lights etc) to just
work when I flick the switch. This is further complicated by the need
to not run other things - the battery charger is the only one that
comes to mind - from the inverter.

I am thinking about using a relay which will automatically disconnect
the inverter from the internal cct breaker and fuse panel if shore
power is connected. The same relay can also connect up the shore
power only circuits.

To do this seems simple... I use a 3 or 4 pole DT relay which is
energised by the shore power feed and will connect the feed to the
fuse panel input. When shore power is removed the relay will switch
the inverter output to the fuse panel input and disconnect the
battery charger.

Does anyone see a problem with this? The only worry I had was that
there could be an issue with voltage spikes when the mains is
unplugged and
some motor or coil gets connected to the inverter as its field
collapses (which may or may not be actually on). Presumably the
inverter is protected against such things cause by the DC power
vanishing but having the relay there means that the voltage switched
on to the inverter when the contacts eventually close could be quite
high. Do inverters normally have protection against such transients?

Alternatively, a 12VDC energised relay could be used that is on the
same switch as the inverter power. It would then disconnect the shore
power
if the inverter is on. This has a couple of draw backs. 1) I need to
run the relay whenever the inverter is to be used (ok I know it is
insignificant but... well - you know!..) 2) I don't get an option for
automatic fail over if shore power fails. Which may be a good or bad
thing but at least it is an option. 3) the big spike could end up on
the shore power plug but I don't think will be any worse than when you
unplug the shore power by pulling the plug out.

Thanks in advance,

Steve

We have a 3-way switch (Off, Inverter,Shore Power) on our Beneteau 50. This
is the first switch we use on entering the boat. The battery charger is
wired to only operate when the switch is on Shore Power. Seems to work OK.

Dennis.


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