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Posted By Topic: combination solar charger/dist board in a caravan

Apr 10 2019 07:47

I have a customer who wants to install one of these in his caravan. I can't see why it'd be an issue, holding it alongside 3001. The data sheets don't show the neutral drawings, to know whether they're switched with the phase.

It obviously isn't identical to either Figure 3.1 or 3.2, however to me "similar arrangement" allows different methods.

I can't deduce whether it complies with the remainder of or though. Anyone encountered one of these or have any input? I've already verified that an SDoC is available. Thanks.

Apr 10 2019 08:58

Have you checked that it is NOT possible to supply 230 V from the inverter back into the mains connection of the connectable installation by the supply lead.

The isolation required needs to be done with a suitably rated (500 Volt grade isolation) because if NO protection the supply lead plug pins may become alive if NO isolation protection is provided.

Have you checked on the size and weight of the batteries to see if the gross weight of the connectable installation does NOT exceed the gross maximum weight permitted to travel on NZ roads.

You need to provide for other items in the vehicle so the batteries alone should NOT be taking ALL of loading available from the nett weight to the gross maximum weight limit.

Apr 10 2019 10:15

This unit does not comply with currently-cited Standard.

For an alternative supply; the changeover device must provide isolation between the two (or more) supplies; i.a.w This unit's line diagram shows that there is a common connection teed off the normal supply, with NO switching at all.
No switching is nowhere near "similar" to a change-over switch.

Currently-cited edition of "3001" does not allow for any other formats, though a UPS could be used, plugged into an outlet.
The "or similar" refers to possibility of using contactors (NOT relays) to do the changeover.

There appears to be some sort of relay on the a.c input. Not clear whether this is the "transfer switch" listed in the spec sheet as having a 16 A rating.

There's another in the earth connection; but switching of earthing conductors is forbidden always and everywhere.

The function of these devices isn't clear.

I haven't followed up the link to the software info; but I note the overall function can be set up as either grid-connect or standalone; and that one of the outlets can only be used when there is grid supply available.

For the grid-connect option, the set-up will not allow inverter to operate without grid supply. So not very useful in a caravan.
For stand-alone, the inverter will operate ;but it's not clear whether the normal a.c. supply is isolated.

Depending on how the a.c. input relay / contactor operates, and whether it has an isolation rating; this set-up could result in the unit livening the pins of the appliance inlet / supply lead. Such back-feeding is dangerous, and illegal.

Electronic switching, and even normal relays, cannot provide the required isolation function

Standards conformance is to EN Standards, which is UK. They will be based on but likely amended from, IEC Standards. So can't rely on them complying with the original IEC, which is mostly what's listed in Schedule 4 of ESRs.
60335-1 is household appliances; general.
60335-2-29 is for battery chargers.
6100-3-3 is EMC compliance.

None of the standards listed applies to inverters.

Note that clause requires any inverter wired into a connectable installatuion to be either isolated or RCD-protected i.a.w. AS/NZS 4763. Thats the Standard for portable inverters; but for this application don't have to comply with all of it, just the isolation / RCD protection aspects.
This one appears to be RCD protected, but nothing to suggest compliance with "4763".
RCDs typically used in UK are Type AC. No info as to the Type of the internal RCD, so can't count on it complying for NZ. Would need to use one output fed via Type A RCD, and disable the other outlets.

The way I see it, installing this unit would be an expensive gamble. But would be worth asking for a copy of the SDoC, and seeing what standards it claims compliance with -
checked against the Standards in Schedule 4.


Apr 10 2019 11:03

Here's the manufacturer's product webpage:

Apr 10 2019 11:14

What is the exact model?


Apr 10 2019 13:21

EN standards are NOT UK standards at all, they would be labelled BS.

EN standards are IEC standards ususally are irectly adopted by the European Common market, and in general, are direct adoptions of the IEC standard of the same number.

Any changes for individual EU member countries will be detailed in a Country Note schedule in the standard.

EN (IEC) 62109 will be more detailed than the joint AS/NZS 4763 and is the refernce standard used by AS/NZS 4777.1 for grid-connect inverters. IEC 62109 does contain a number of options but it is a complex standard to use in the field, it was developed mainly for use by Test Houses when approving grid-connection inverters.


Apr 10 2019 18:14

I meant European, don't know why I typed UK.

Point remains that even if this unit does comply for NZ; showing that it does will be tricky.

And installing it into a connectable installation in a manner compliant with "3001" will likely be impossible.

Apr 10 2019 20:00

I think that relay on the earth is to provide an MEN link when operating in standalone mode, and remove it when in grid-tie or direct mains. I'm pretty sure that's allowed in some of the examples for changeover switches.

I agree that it almost certainly can't be used unless it's possible to completely disable (and mechanically interlock against?) the grid-tie and PowerAssist features, and interlock the mains and inverter supplies.

Apr 11 2019 06:48

Thanks for the in depth replies. I'm unsure of the exact model, but either way will let them know to stick to the tried and tested.

Apr 11 2019 07:06

Yes, I suppose that switch in the earth connection could be the switched N-E connection is required for isolated-outputinverterN-E link; closed only when inverter is operating in order that the load is supplied by something resembling a MEN system. Without this, the RCD(s) would not have an earth reference; so would not provide required fault protection. this is an RCD-protected output; so the N-E connection must be permanent.

Appears to be connected to a.c. input active between mcb & RCD, but being only a single-line diagram can't tell .

Diagram doesn't show an "outline" for the unit, but the earth symbol being aligned with the output terminals suggests its a connection to body of unit; again this should always be earthed.

Apr 11 2019 09:39

Alec notes:

> Yes, I suppose that switch in the earth connection could be the switched N-E connection is required for isolated-outputinverterN-E link; closed only when inverter is operating in order that the load is supplied by something resembling a MEN system

That's exactly it, to quote the manual:

"The EasySolar is provided with a ground relay (relay H, see appendix B) that automatically connects the Neutral output to the chassis if no external AC supply is available. If an external AC supply is provided, the ground relay H will open before the input safety relay closes. This ensures the correct operation of an earth leakage circuit breaker that is connected to the output."

If the inverter is treated as an appliance, this makes really good sense, as then stuff plugged into the inverter will always have a valid earth irrespective of whether the inverter is running stand-alone, or the inverter is plugged into a (MEN) installation.

It gets more difficult if the inverter is "installed" part of an installation, as then it falls foul of the regulations. Which is a bit of a problem, a the inverter is doing the right thing, although maybe not in the right manner; there is a need to recognise that under some circumstances MEN links are a movable feast.

I've written before that there are UPS operating scenarios that can result in the load not "seeing" a MEN bond due to the bond being upstream of the UPS, and the load is being fed by the UPS inverter effectively as a floating supply. Again, MEN links, movable feaast.

Apr 11 2019 14:14

And one of the reasons that other system of supply are being considered (but are NOT in force yet).

An isolating transformer if correctly used is sometimes a way around the current ESR 2010 requirment that MEN is only system of supply currently mandated.

But it requires care and skill to get the arrngement to comply with the ESR 210 requirements

Apr 12 2019 08:55

Much simpler all round if he keeps the entire PV/inverter side at 12 volts into a standard changeover into the switchboard.
Dumb question
How much 230 volt stuff is there in the caravan/motor home anyway?
I do over 70 EWoFs a year so I see a few......
My advice would be to keep as much gear in the van to 12 volt.
In my view about all you need 230 for is
electric blankets
mains charger for the 12 volt system
and that's about it, all the rest is done with 12 volt these days.
Had a customer last year who ran her internet business out of the motor home while her partner went fishing. They seemed to be away about 2 weeks a month