3000VA isolation transformer

[Dacian Todea]

As I mentioned a few days ago in the 3500W inverter post https://groups.google.com/g/electrodacus/c/-ep59RSGjdo/m/LNlu0PsKAgAJ

I ordered an insulation transformer for it a 2500VA one from Mouser but after some time they canceled the order as they did not had in stock and the transformer manufacturer that supposed to ship it to me refused to do so.

So I went to Digikey and they had transformers in stock so I git this 3000VA that had free shipping and I just received today (fairly fast shipping as it shows as shipped from Winnipeg for some reason). Anytime I ordered anything from Digikey it was always shipped from US.

Below a few photos of this large and heavy monster. For the 3500W inverter a 2000VA transformer will be more than adequate I just did not found anything in stock around that size.

I'm super busy this week but maybe I can test the inverter and transformer combo tho I will prefer to wait for the battery (if it will ever arrive). If not I will connect to my A123 system battery and fully test so I can recommend / or not this 3.5kW inverter.

It was super nicely packed in a wood crate inside the cardboard box.

 

Box is 30kg but the transformer itself is 26.5kg

The manufacturer same as the one for the 2500VA I wanted to get from mouser.

It even has a strap molded in the middle epoxy core to have an easier time handling it.

Is just 208 or 240V input but output can be configured as 120 or 240 the other smaller transformer had also 120/240 input option not that I need that in my case.

The wires are fairly nice with 150C insulation rating.

 Here is the link to digikey https://www.digikey.ca/en/products/detail/triad-magnetics/VPM240-12500/5721784  it was 467CAD with free shipping but I see they no longer show Digikey stock and they showed quite a few now is just the 9pcs factory stock.

Do not buy those amazon, ebay isolation transformers with case and sockets as they are way overrated and that is why they look cheap but they are not.

A true 2000VA will be enough for the 3500W inverter because the transformer can handle 150% even 200% for a few minutes and usually your loads will be thermostat controlled like an oven and then average power will be much lower than peak power that is only until it gets to temperature.

[Plamen]

     Hi Dacian,

Apart from getting 120V is there any other reason for using that isolating transformer?

[Dacian Todea]

My main reason in using the transformer is to get the 120V needed for most appliances here in North America.

The inverted internally should already be isolated as the battery bidirectional DC-DC converter is isolated but is likely not isolated from solar PV so if medical grade isolation is need for some reason then the isolation transformer will also make sense.

But the most important role of the transformer is to have the 120V as this inverters are only provided as 240V and while there are some other versions with 120V output those are so much more expensive than adding the transformer will still be slightly cheaper.

For example this will be a similar construction and design https://www.amazon.ca/Hybrid-Inverter-Controller-Lithium-Batteries/dp/B096XRJW7G  but is much more closer to the old 2400W inverter that I have in characteristics other than this is 120V output so just 4500W peak probably a single DC-DC transformer vs this new inverter that I got that has 7000VA peak for up to 5 seconds (will need to test that claim but is probably correct).

Also I got an overkill transformer as a 2000VA one will have been plenty to fully take advantage of this inverter.

The thing is that they use IGBT in this designs and they prefer to work with that much higher voltage as it will be more efficient thus they concentrate on the 240V market that is also larger.