Sumry Inverter-Charger in Caravan

[BaronVonChickenPants]

This is a continuation of the discussion from: http://forums.aeva.asn.au/viewtopic.php?p=75374#p75374

Summary of the Sumry: Torroid based LF inverter charger with low standby current, available input Voltages of 12,24,48,etc
https://www.alibaba.com/product-detail/ ... 32ecbPxyFR

Also available locally via Bit Deals Ebay:
https://www.ebay.com.au/itm/283451974467

Discussion is regarding correct connection of the inverter for use in a caravan:

Hi Doggy,
I was impressed with your report and ordered the same unit from Bit Deals for my caravan.

The unit has happily performed all of my work bench tests and I am ready to install it into the van.

I'm curious if you were able to connect an earth neutral bond or if you made do with the floating neutral from the inverter output?

Thanks,
Jordan

Hi Jordan,
I added:

a. Neutral link to ground.
b. Ground to existing house ground (copper stake).

Incidentally, Hary who started this thread has successfully used his with his arc welder.

Cheers,
Dave

Thanks Dave,
I was hoping to connect this way, just wanted to check someone else had done it first before I let the smoke out.

Regards,
Jordan.

Hi Jordan,
Yes, the output is totally floating (insulated) from everything else so there is absolutely no problem.
Also, my unit continues to function beautifully.
Cheers,
Dave

a. Neutral link to ground.
b. Ground to existing house ground (copper stake).
NO definitely do not do this is against the rules you will have two earths on the neutral!!!!



With the newer units they have a relay for the neutral link.
If you are going to connect the inverter to a grid or generator with an existing neutral link you have to use a relay to switch the earth onto the neutral when the inverter is operating but to remove it when in by-pass and the grid or generator neutral earth is being passed through it is not allowed to have more than one earth on the neutral so only in stand alone no grid or generator with neutral link should you bond the output neutral to earth!

Not sure you understand my setup.

The house is bonded in the normal manner. The grid does NOT connect to the inverter in any way. In other words I am NOT using the grid input (which is not connected) nor the ATS nor the inverter's charger.

Things connected to the inverter are totally separate from things connected to the grid. So they experience the neutral bonded to ground which is copper stake at the same location as the house ground.

Regds,
Dave

Skip the copper stake bit, that is to make a connection back to the transformer or the power generator. You have the power generator on board in the form of an inverter. If the generator is a plug in device and has a fault to the metal frame and that is sitting on the ground, the stake will make a circuit back to the generator and that will become the earth neutral link, or anyone touching the conductive body will become the earth neutral link if the are bare foot on wet ground.
If you are not going to connect to the shore power at any time then you can get your sparkie to make an earth/neutral bond after the inverter. Be very careful about connecting and earth wire to the inverter body itself unless it is in the specified spot, many inverters use a live shell inside the inverter that is isolated from the outer body, earth that and the smoke comes out big time.
Another way around the problem is to leave the system floating and fit an RVD after the inverter. These sense voltage rather than current on the earth circuit and switch the power off without any current needing to pass through the poor sod who got themselves tangled up in the active wires.
Please, keep in mind only one class 1 appliance can be safely connected to a floating supply, if that happens to be a generator plugged into the shore power socket, the RV is the first class 1 appliance in the circuit as it has the earth bonded to the conductive frame and panels. A short to the body from either line 1 or line 2 of a floating supply turns it into an earth/neutral supply and the other line becomes the active. A second appliance with a fault to the active that comes into contact with the user will not trip the circuit breaker nor will the user feel anything, but if the user also touches the conductive parts of the body work, they become another appliance with all the available current passing through them. The RCD does not see this as a fault, the user is just another appliance it needs to power.

T1 Terry

Terry,
Just making sure I'm clear, you are saying to skip the earth neutral bond, leave the neutral floating but have the inverter output via an RCD to detect leakage.

In a caravan with double pole power points this "shouldn't" pose a safety risk. Should the chassis still be staked to earth?

The Sumry inverter dry contact is only for low voltage activation, it doesn't support MEN connect/disconnect.

The inverters casing is connected to earth on the AC input and AC output which would in turn be connected to the chassis of the van. But is isolated from the DC input or AC output.

On a separate note:
Has anyone had any luck communicating with the RS232 port on these inverters?

Regards,
Jorda

[doggy]

Hi Jordan,
I have been able to communicate with the RS232.
Can do some basic stuff and read voltages etc.
Hary has also been able to do this.
But neither of us is actually using it.
I am using the remote control panel and also have a very large DC contactor on the battery side.
Cheers,
Dave

[T1 Terry]

An RVD, not an RCD because an RCD will only work if there is an earth/neutral bond before the RCD. If you are never going to plug into shore power that will have its own RCD and earth/neutral bond, then get your sparkie to make the earth/neutral bond after the inverter but before the RCD. The problem is if you do try to plug into shore power that does have its own RCD, your second earth/neutral link will be seen as a fault and trip the supply RCD.
Some links to RVD suppliers on Google https://www.google.com.au/search?source ... 9396213028 We bought our units through a seller who is now part of rvdsafe.com.au, he called himself powerstream before that on a few forums.
These have been the fuel for many a heated thread on other forums, I believe the members here are above such things, otherwise I wouldn't have even mentioned it. Arguments with people who show they don't really understand the subject just get on my goat. If there is a logical argument against using one based on solid evidence then by all means, please present it. After being belted more than once from a poorly wired van direct from the manufacturer (screw through the cable when installing cupboards etc the most common) I'm definitely in favour of an RVD if you plan to use shore power and your inverter does not auto switch the earth/neutral link.

T1 Terry

[BaronVonChickenPants]

Thanks Terry,
That makes more sense. At first I thought RVD was a typo, C being next to V, but I thought RCD's don't work with floating neutral.

I understand that with an MEN but no earth stake, like a vehicle on the road, you are not pulling neutral down to earth but instead pulling the chassis UP to the floating neutral voltage. Something I hadn't fully considered until your comment.

Getting an RVD installed is the answer I was looking for.

Regards,
Jordan

[doggy]

For those with a Sumry or contemplating same:

I now have my 5kVA unit running two LG split air conditioners. Each is 6,000W and the SUMRY handles both with ease, even on maximum cooling or maximum heating both running together.

The Sumry is driven by 8x AVASS bus cells.

Cheers,
Dave

[T1 Terry]

For those with a Sumry or contemplating same:

I now have my 5kVA unit running two LG split air conditioners. Each is 6,000W and the SUMRY handles both with ease, even on maximum cooling or maximum heating both running together.

The Sumry is driven by 8x AVASS bus cells.

Cheers,
Dave

I am assuming this is 6,000w cooling/heating and not energy draw, how high does the max current draw at the battery reach when both units are in boost cool mode after they have fully ramped up?

T1 Terry

[doggy]

Correct.

Max current drain, both on full bore is 135 to 145 amps when the cells are fairly well charged (about 80%).

Load on the inverter is approx 70%. Efficiency around 90%.

These units have a high COP (which is the main reason I chose them).

Regds,
Dave

[T1 Terry]

Thanks Dave, so around the 3700w mark to run both air con units flat out, not bad at all. We installed a 12v 700Ah lithium battery a number of yrs back and the owner decided last summer that he should have an air con installed because he now had batteries that could handle the load. He installed a Victron 3000va inverter and all ran well for about 25 mins, then alarms sounded in the electrical cabinet and then everything went off. As long as the air con wasn't on it would restart and all was well, but with the air con running it lasted about 20 mins and screaming alarms and off. I asked him to watch the Victron BMV and it sat at around 2,000w for the 20 mins, then it started to climb and the alarms started at around 4,000w and dropped out at around 5,000w. Not a bad over load capacity but why the sudden climb in energy requirement.
Turned out he had told me the maximum draw of the ceiling cassette unit, not the outside unit and the cassette unit. It was rated at 7.5kW cooling and heating but the only information was the compressor stall current.
Suggested adding a second Victron 3000va in parallel and tried it again. Same deal, sat around the 2200w this time for the 20 mins, then slowly wound up to 7,000w for 5 mins and then it slowly wound back to sit at 2,000w again and remained at that all the time it ran for the rest of the day. On the eco setting it didn't climb past the 2,200w mark so if he'd tried that he could have used the one inverter

T1 Terry