Changeover Switch for 240v Fridge

Gundog · Guru

Changeover Switch for 240v Fridge

Mike Harding · Guru

CRITICAL: Ensure the change-over switch is "break before make" and NOT "make before break".

And, of course, the switch must be rated for 240V AC and, say, 10A switching.

What you suggest may work in theory but you may find issues trying to start the inverter with a significant load already in place - depends upon the particular inverter.

I doubt an electrician will install your switch unless it's new and you have the specification otherwise he is taking the risk of installing equipment not specified for this purpose.

I will say that I don't like this way of doing it - is it really so hard just to swap plugs?

I believe there are reasonably priced devices on the market specifically designed to switch to a standby supply in the event of mains failure - it's a technically trivial task - one of these would be a better bet for you.

Edit: spelling error.

-- Edited by Mike Harding on Saturday 2nd of May 2020 01:26:58 PM

Gundog · Guru

what is the difference between break before and make before, the switch is a manual 3 position switch L O R, which was installed by a sparkie.

The inverter is a Victron Pheonix 12/350va, which has a remote switching.

Mike Harding · Guru

If it was supplied and installed by an electrician then, most likely, it will be suitable for the job.

[Note: the moving contact which does the actual switching is called the wiper]

Break before make = there is a period of time after the wiper has broken connection with contact A before it makes connection with contact B.

Make before break = the wiper makes connection with contact B before it breaks connection with contact A.

The former switch is used for your sort of requirement, the latter for when you don't wish to loose power to the load BUT the supplies MUST be able to withstand being momentarily shorted.

markf · Senior Member

Mike Harding wrote:
CRITICAL: Ensure the change-over switch is "break before make" and NOT "make before break".
........
I will say that I don't like this way of doing it - is it really so hard just to swap plugs?
I believe there are reasonably priced devices on the market specifically designed to switch to a standby supply in the event of mains failure - it's a technically trivial task - one of these would be a better bet for you.
Edit: spelling error.

-- Edited by Mike Harding on Saturday 2nd of May 2020 01:26:58 PM

I just use the plug swap method. Simple and easy.

I wouldn't use the inverter remote switching at all - it adds an extra layer of complexity. If you're running off the mains then presumably you are also charging the batteries via a charger in which case the standby current of the inverter is covered by the charger and doesn't matter. If you're running off the inverter then the losses are just part of the power cost of running it.

If you just want to change over from the mains to the inverter and back again then a simple and cheap(ish), manual Open Transition Transfer switch (break before make) is the way to go. If you want to do it automatically then the price starts to go up - around $400 - $500 at least.

In short. I wouldn't worry about remote switching of the inverter and I'd just use the plug swap method or a simple transfer switch and leave the inverter switched on. The standby power for the Phoenix is low - about 5W I think.

-- Edited by markf on Friday 8th of May 2020 01:06:57 PM

-- Edited by markf on Friday 8th of May 2020 01:08:41 PM

oldtrack123 · Guru

Gundog wrote:
I have a changeover switch installed to switch between 240v mains and an Inverter.
The inverter has a remote switching ability that was never used when the changeover switch was installed, I'm thinking of the best way to use the remote facility, looking at the changeover swith there is a 3rd row of switch not used 1st row is Active 2nd row is Netural and the Earths are connected together away from the switch.
With the aid of Mr Google and stickybeaking at the actual switch I was able to provide a diagram of connections
I was wondering if I cound get a sparkie to run a pair of wires from the remote switch facility on the inverter to 11 & 12 which would switch the inverter on when battery is sellected.

You require a multi pole [3pole] change over switch[Break before make]15A min, wired in accordance with the Standard AS/NZS 3001] So that the van RCD is fully operational from either source

oldtrack123 · Guru

markf wrote:
Mike Harding wrote:
CRITICAL: Ensure the change-over switch is "break before make" and NOT "make before break".
........
I will say that I don't like this way of doing it - is it really so hard just to swap plugs?
I believe there are reasonably priced devices on the market specifically designed to switch to a standby supply in the event of mains failure - it's a technically trivial task - one of these would be a better bet for you.
Edit: spelling error.

-- Edited by Mike Harding on Saturday 2nd of May 2020 01:26:58 PM
I just use the plug swap method. Simple and easy.
I wouldn't use the inverter remote switching at all - it adds an extra layer of complexity. If you're running off the mains then presumably you are also charging the batteries via a charger in which case the standby current of the inverter is covered by the charger and doesn't matter. If you're running off the inverter then the losses are just part of the power cost of running it.
If you just want to change over from the mains to the inverter and back again then a simple and cheap(ish), manual Open Transition Transfer switch (break before make) is the way to go. If you want to do it automatically then the price starts to go up - around $400 - $500 at least.
In short. I wouldn't worry about remote switching of the inverter and I'd just use the plug swap method or a simple transfer switch and leave the inverter switched on. The standby power for the Phoenix is low - about 5W I think.

-- Edited by markf on Friday 8th of May 2020 01:06:57 PM

-- Edited by markf on Friday 8th of May 2020 01:08:41 PM

Hi Mark

you are aware that with the plug swapping method you will not have a fully operational RCD when on inverter power???

markf · Senior Member

Hi mate I use an RCD/RVD which reliably trips at 10mA leakage. With a straight 18mA RCD the inverter faults and turns off at about 15mA leakage.

Peter_n_Margaret · Guru

markf wrote:
Hi mate I use an RCD/RVD which reliably trips at 10mA leakage. With a straight 18mA RCD the inverter faults and turns off at about 15mA leakage.

Yes, the RCD/RVD will be effective, but as Oldtrack says, because of the way it works, the RCD alone will not.

Cheers,

Peter

oldtrack123 · Guru

Peter_n_Margaret wrote:
markf wrote:
Hi mate I use an RCD/RVD which reliably trips at 10mA leakage. With a straight 18mA RCD the inverter faults and turns off at about 15mA leakage.
Yes, the RCD/RVD will be effective, but as Oldtrack says, because of the way it works, the RCD alone will not.
Cheers,
Peter

Exactly right biggrin smile

And actually, the RVD does not monitor current, it monitors voltage to earth.

When that voltage to earth reaches the designed point, it, the actual RVD[ Residual Voltage Device] trips the RCD.[residual current device]

The load-carrying/current capacity of the RVD component itself is quite low, so it must always be used in conjunction with an RCD for power switching.

Note ; there are actually several types of RVDs available from Powerstream, so make sure you, or more correctly , your electrician get the correct unit.

markf · Senior Member

Hmmmm. Perhaps I shouldn't have just blithely said that I use the plug swapping method without specifying what our protection mechanisms are.

A fair bit of time and effort went into our setup so that no matter what, we'd be protected. On top of that, before any trip away it all gets tested. Who knows where water can get in or which cables can be abraded. I'd rather know that no matter where the 240V comes from and how dodgy the earth is we're protected unless we do something deliberatly and really stupid.

As others have said. An RCD on its own is potentially lethal if where you're plugging in to doesn't have a proper earth. Think inverters, generators and stray outlets on poles.