Is the auto changeover relay duff?

JockandRita

JockandRita

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Since May 05 (Ex Tuggers).
Some advice needed please. :)

In late December, when getting the (new to us) MH ready for Spain, the boss asked me to show her how the inverter worked. "No problem" says I, and forgetting that the MH was plugged in to the mains, I turned on the inverter, only to hear an almighty "BANG". :eek:
I immediately unplugged, and searched for any signs of smoke or damage. None found thankfully. I tested the inverter which worked correctly. I then turned it off, and reconnected the EHU. All sockets working fine. (y)

On the way down to Spain, the inverter worked a treat. When on the site, I was experimenting (as you do) with the solar panels and the inverter. As the sun went down, I reconnected the EHU, forgetting that the inverter was still on. All of a sudden, there was a rapid switching sound, like a relay constantly operating, then nothing. The inverter had completely died. Everything worked fine on EHU.

Long story short, today I fitted a replacement pure sine wave inverter, which worked a treat when tested after installation. However, when I tried it again, there was no power to the MH sockets. The RCB had tripped. With the inverter off I reset the RCB. With the EHU reconnected, the RCB tripped again with no sockets in use at all. :(

All I can think of is possibly a duff auto changeover relay, as in the photos.

1585257355010.png


The orange cable is the input from the inverter, with the white cable connecting to the relay.

1585257503565.png


There are no signs of scorching anywhere through the transparent relay body, however, having searched the internet using the number of the base, I have ordered a replacement from R S Components, to arrive tomorrow (all being well).

Can anyone advise further please?

Cheers,

Jock. :)
 
What is the inverter make? Is it suitable to be connected to mains to synchronise with the mains sine wave? Or is a stand alone with only AC output. If later than most stand alone have neutral conected to chassis / ground. A separate rcbo or rcd should be used only for that outlet. If you connect it to the rest of the ac board it will loop thru the existing neutral and trip.
 
hi jock.. know nothing about inverters designed to be wired into the vans 240v system, but is the purpose of the change over relay not to disconnect the inverter when it senses the ehu connected.. it doesn't sound like yours is doing that..
if the rcb is tripping on ehu and inverter power there is obviously an earth leakage on the distribution system which would be a separate issue from the change over relay...just my thoughts..
Andy
 
Raul said:
What is the inverter make?
Click to expand...
The original was a Merlin M Power 2000. This one is an Edecoa 2500W.
https://rover.ebay.com/rover/1/710-...0001&campid=5338547443&icep_item=401925657359

Like the Merlin it replaced, it has an earth lead connected to the chassis.

andy63 said:
hi jock.. know nothing about inverters designed to be wired into the vans 240v system, but is the purpose of the change over relay not to disconnect the inverter when it senses the ehu connected.. it doesn't sound like yours is doing that..
if the rcb is tripping on ehu and inverter power there is obviously an earth leakage on the distribution system which would be a separate issue from the change over relay...just my thoughts..
Andy
Click to expand...
That was my thoughts too Andy, ie, if that relay failed, then it would explain the problems from the start.
I'll install the new relay when it arrives, and take things from there.

Re the RCB tripping on EHU and on the inverter, it's only just started doing that this afternoon, but not initially, as things were working fine.

Cheers,

Jock. :)
 
This site contains affiliate links for which MHF may be compensated.
Sounds like the relay has been wired incorrectly and when the EHU is connected the incoming mains is connected to the inverter output precisely what is is supposed to prevent.

Your mains cables look far too small for the size inverter you are using.

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I like you guess at the relay.

You need to simplify and test. Undo the wires to the inverter so you eliminate that. Hook up and see if it still trips.

It only takes a whisker in that relay to trip the MCB.

I'd make up 3 male jumper wires so you can feed incoming mains to the RCB, eliminating the relay and inverter, this is good insurance for the future.
 
Lenny HB said:
Sounds like the relay has been wired incorrectly and when the EHU is connected the incoming mains is connected to the inverter output precisely what is is supposed to prevent.
Click to expand...
hilldweller said:
I like you guess at the relay.

You need to simplify and test. Undo the wires to the inverter so you eliminate that. Hook up and see if it still trips.

It only takes a whisker in that relay to trip the MCB.

I'd make up 3 male jumper wires so you can feed incoming mains to the RCB, eliminating the relay and inverter, this is good insurance for the future.
Click to expand...
And that gents, is where I come to a halt, ie, I'd be out of my depth. :(

Lenny HB said:
Your mains cables look far too small for the size inverter you are using.
Click to expand...
The original Merlin inverter was a 2000W job, but the highest consumer is the 800W combi microwave (1600W on start up). I couldn't get the Edecoa 2000W unit in pure sine wave, hence the 2500W listed above.
When everything was working fine, on the way down to Spain, I did check that cable first time round for heat generated, whilst the microwave was in use. Nothing found.

Cheers,

Jock. :)
 
Hi Jock

You know that I connected both sources live at the same time and blew a fuse in the mains lead, after that I questioned the ability of that relay to effectively separate the two mains sources, I even questioned wether it was designed to do that? I did give the relay a good looking at much as you have done but then I found the blown fuse in the mains lead and after that I never connected the two at the same time so all was good, it is possible that it is not wired correctly in some way but when I replaced the inverter I just replaced the wires like for like feeling confident in my ability to do that but I would not have fitted the changeover from scratch as that is beyond my pay grade.

We did have an issue with the RCD tripping at one time but that turned out to be a plug with a dodgy connection, by that I actually mean that whoever fitted the inverter and changeover had rewired the mains into that box on the Right when you are looking at the changeover, there is a male/female plug on the distribution board but they had put male terminals in each one and pushed the plugs together so the tips were just touching eventually overheating and tripping, I am not suggesting this as the cause of RCD tripping more another question mark agains the original fitting.

Martin
 
hilldweller said:
You need to simplify and test. Undo the wires to the inverter so you eliminate that. Hook up and see if it still trips.
Click to expand...
Which wires please Brian? Do you mean the 3 x pin plug from the inverter? If yes, I tried that this afternoon, and the RCB reset no problem. As soon as I either plugged in to the inverter and switched on.................or plugged into the mains, the RCB would trip.

funflair. Thanks for contributing Martin. I don't like to keep bothering you with queries, hence my thread.

funflair said:
We did have an issue with the RCD tripping at one time but that turned out to be a plug with a dodgy connection, by that I actually mean that whoever fitted the inverter and changeover had rewired the mains into that box on the Right when you are looking at the changeover, there is a male/female plug on the distribution board but they had put male terminals in each one and pushed the plugs together so the tips were just touching eventually overheating and tripping, I am not suggesting this as the cause of RCD tripping more another question mark agains the original fitting.
Click to expand...
I'll have a look at that tomorrow Martin. (y)

Thanks to all so far for your contributions. Much appreciated. :)

Cheers,

Jock. :)

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hilldweller said:
So after the post by the previous own I'd say STOP now before it really goes tits up. Any decent electrician should be able to check it out.
Click to expand...
I'm not going to get a hold of one of those in the very near future, but I do appreciate what you say Brian. ;)

Cheers,

Jock. :)
 
JockandRita said:
Which wires please Brian? Do you mean the 3 x pin plug from the inverter?
Jock. :)
Click to expand...

Yes.

With no inverter and no hook up nothing can trip the RCB ( sorry I typed MCB earlier, they are next to the RCB ). The RCB need 240V to make it trip.

So it trips if either 240V supply is connected.

Next: flick off all the MCBs next to the RCB to see if something within the MH is damaged and tripping it. With the relay "rattling" power on and off anything electronic, like the battery charger could have got fried.

Leave the inverter unplugged and off - just to get back to basic hook-up power. Hook up. If it trips then it really does look like the relay.

DO NOT connect the new relay, what has now come out makes the wiring suspect.

What I would do at this point is make up 2 spade leads ( not 3, I assume the greens are all joined in a screw connector ), only a few inches, then wire the incoming hook-up to the wires going to the RCB. I would expect brown--brown, blue--blue.
 
JockandRita said:
I'm not going to get a hold of one of those in the very near future, but I do appreciate what you say Brian. ;)

Cheers,

Jock. :)
Click to expand...

Fair enough. Though I would have thought electricians could work more or less normally, just as plumbers to keep us going. They specifically say hardware places to stay open.
 
JockandRita said:
Which wires please Brian? Do you mean the 3 x pin plug from the inverter? If yes, I tried that this afternoon, and the RCB reset no problem. As soon as I either plugged in to the inverter and switched on.................or plugged into the mains, the RCB would trip.
Click to expand...
Correction................As soon as I plugged in and turned on the inverter, the MCBs tripped.
When I then switched off and unplugged from the inverter, I reset the MCBs, and plugged in to mains. That's when the RCB and MCBs tripped............................also tripping the supply from the house garage I am plugged into, at the consumer unit. :whatthe:

Apolgies for the wrong use of technical terms. ;)

hilldweller said:
Leave the inverter unplugged and off - just to get back to basic hook-up power. Hook up. If it trips then it really does look like the relay.
Click to expand...
Yes, it trips as above Brian, including the house supply. :(

Cheers,

Jock. :)
 
hilldweller said:
So after the post by the previous owner I'd say STOP now before it really goes tits up. Any decent electrician should be able to check it out.
Click to expand...

Ha, the only way to stop a retired fireman from messing with something is by cutting his hands off, even then they are likely to find a way of messing with it !! what they are very good at is following instructions and diagrams, so if anyone can sketch out what goes where, i have every confidence he will sort it (and get it checked properly when he can of course!)

:cool::cool:

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MisterB said:
Ha, the only way to stop a retired fireman from messing with something is by cutting his hands off, even then they are likely to find a way of messing with it !! what they are very good at is following instructions and diagrams, so if anyone can sketch out what goes where, i have every confidence he will sort it (and get it checked properly when he can of course!)

:cool::cool:
Click to expand...
Good morning my former "Brother In Arms". :)

Rita is always telling me off for fiddling with things. :whatthe: Hmph, I should be so lucky :( ............................. :rofl:

Cheers,

Jock. ;)
 
you can fiddle with it all you like, but it wont get any bigger, is probably what she meant ....
 
Maybe the inlet socket on your van as well

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My thread can be found here. https://tinyurl.com/y5gjksrm

A couple of wiring diagrams are shown below. In hindsight I think I would connect the changeover relay differently. I wired it so the normally closed contacts connect the inverter output to the MH sockets. I think it is better to connect the EHU input to these instead. The reason for this is if you are on a site with low amps, we've come across 3A a few times, then if you want to run something with a high load such as a hairdryer or coffee machine you have to disconnect the EHU before you can turn on the inverter. By wiring it the other way round you can turn on the inverter and it will disconnect from the EHU automatically. The only thing to be careful is to check the relay opens the contacts before closing the other pair. I suspect they all do but it would be bad news if both the inverter and EHU were connected together as they would inevitably be out of phase with each other.

240v wiring diagram.jpg

wiring diagram.jpg
 
Just to confuse you even more this is how I wired mine, I haven't shown separate Live & Neutral wiring for drawing simplicity.
Like John I wired mine with the N.C. contacts to the inverter so the relay changes over only when EHU plugged in. My reasoning was I rarely use EHU so less draw on the 12v as the relay would need to permanently on when not on EHU. In the situation John describes you only need to turn off the MCB or RCD to allow the inverter to be used.

1585307043936.png
 
JockandRita said:
Correction................As soon as I plugged in and turned on the inverter, the MCBs tripped.
When I then switched off and unplugged from the inverter, I reset the MCBs, and plugged in to mains. That's when the RCB and MCBs tripped............................also tripping the supply from the house garage I am plugged into, at the consumer unit. :whatthe:

Apolgies for the wrong use of technical terms. ;)


Yes, it trips as above Brian, including the house supply. :(

Cheers,

Jock. :)
Click to expand...

RCB and MCBs - all of them - full house - you win a holiday in Tuscany.

House consumer unit - did the main breaker trip and is it RCB ?

It won't prove much but if you remove the relay totally ( you have documented it ! ), plug into house, now does it trip ?
 
DBK said:
The only thing to be careful is to check the relay opens the contacts before closing the other pair.
Click to expand...

Normally described as "Break Before Make".

But the is an interesting twist to this, these are 240V relays. As you have said the two supplies WILL be out of phase so in effect there could be 240+240 between those contacts. Could they arc ?

Right now I'd say the better way would be two relays and a simple timer circuit. You would not get near uninterrupted supply but it would be safe.

PS.....

KISS - as I had it - one socket from the inverter, if I wanted inverter I plugged it in the socket. It never failed.
 
I've not been able to get out there yet, as my attentions have been redirected to repairing a domestic appliance. All done, and back on the job in hand now. ;)

hilldweller said:
House consumer unit - did the main breaker trip and is it RCB ?
Click to expand...
No Brian, just the breaker for the house garage sockets circuit, where I was getting my power from.


hilldweller said:
It won't prove much but if you remove the relay totally ( you have documented it ! ), plug into house, now does it trip ?
Click to expand...
I'll come back to you on that one Brian, once I have got my coat and shoes on, and checked the input Euro plugs first, and if they are okay, I'm going to try a different EHU source. I might be a while. BANG! :eek: ................. ;)

DBK John and Lenny HB, I'll have a scan over the diagrams later thanks. (y)

Cheers,

Jock. :)

P.S. I ordered the new relay last night, and it arrived earlier this morning. Excellent service. (y)
 
Update........

I used a house socket to source my EHU from, and even used a different lead and Euro plug. Both the RCB and MCB in the MH tripped, as well as the circuit that supplies the house sockets. ☹️

hilldweller said:
It won't prove much but if you remove the relay totally ( you have documented it ! ), plug into house, now does it trip ?
Click to expand...
I took a photo first, then disconnected the relay completely, connected the EHU and again, both the MH and it's external supply tripped...........so, I would imagine that result illiminates the relay.........for now.

What next? ☹️ I can't find any evidence of arcing in any of the photos below, so I am absolutely stumped for now. ☹️

IMG_20200327_123144.jpg
IMG_20200327_123203.jpg
IMG_20200327_130257.jpg


Cheers,

Jock. ?

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