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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I did look at three way switches but could not get one with enough poles
to do everything I wanted. I would need 2 for the live and neutral, one
for the battery charger and then I would also have need something to
turn on the DC power to my inverter (probably an electronic battery
switch driven by another pole). I am guessing that you have something
very flash and expensive which I will wish I had spend money on in a few
years when my stuff is playing up.

Thanks for the reply.

Steve

Dennis Pogson wrote:


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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Steve wrote:
I did look at three way switches but could not get one with enough
poles to do everything I wanted. I would need 2 for the live and
neutral, one for the battery charger and then I would also have need
something to turn on the DC power to my inverter (probably an
electronic battery switch driven by another pole). I am guessing that
you have something very flash and expensive which I will wish I had
spend money on in a few years when my stuff is playing up.

Thanks for the reply.

Steve

Not really, it's a circular 3-way DC switch with a pointer/knob which turns
left, right, and straight up. AFAIR our +/- battery leads (massive) go
straight to the inverter via the main master switches (2,+/-), and there is
an on/off switch on the inverter itself. With the 3-way switch off, turning
on the inverter's on/off switch does nothing, with the 3-way switched to
shore power, the battery charger and all the 12-volt systems are activated,
but the inverter is still out of circuit. Only when the 3-way is switched to
inverter is it possible to activate the inverter and the 240-volt ring main
et al. The only remote switch we have is the gas solenoid in the cockpit gas
locker, actuated by a contact-breaker switch on the main saloon panel. It's
all manual, and all very simple.

Dennis.