230vac single phase output to 220v with a center tap transformer

mrfcc1 Registered Users Posts: 2

I am looking for recommendations or options for  powering my 120/240v electrical panel with a 230 VAC, 50Hz/60Hz (Auto Sensing),  EAsun Isolar SML 5K  5Kva 4000w 48V to 220V 60A off grid Pure Sine Wave Hybrid Solar Inverter Built-in MPPT Solar Charge Controller and Battery Charger with ac input /output 220-240vac single phase only.
I assume I need a transformer just unsure as to whether I can use a dry or encapsulated transformer. Any recommendations would be greatly appreciated


  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    Welcome to the forum MrFCC1.

    Is this for use in North America (central California?) or somewhere with 240/220 VAC as line voltage? In North America, the "center tap" of the 120/240 VAC line is a ground referenced neutral. In other 220/240 VAC native countries, one leg of the 2X0 VAC line is usually ground referenced (may vary by country).

    Are you going to connect to the utility grid as a hybrid/GT capable inverter? Will this hybrid inverter+charger meet your UL/NEC requirements?

    If you are planning on using this system in North America--You probably should get a wiring diagram from EAsun to ensure that the inverter is connected as they expect to the utility.

    Transformer wise, you have two major choices... An "auto" transformer that has only one set of windings. You connect L1/L2 to 240 VAC, and the center tap gives you 120/240 VAC output... However the output of such a transformer is NOT isolated from the AC input... So the Neutral bonding of AC neutral/center tap of North America would require you to "float" L1 and L2 to the hybrid inverter.

    Here is an example of an Auto-Wound Transformer that is used on off grid AC power systems:


    The other major type is a two winding transformer... Isolated from AC In to AC Out of the system... You can have 240 native with ground bonded neutral on the 240 VAC side, and the Neutral Center Tap ground bonding on the 120/240 VAC output of the transformer.

    I did not find many details on your inverter+charger... In the US, L1/N/L2 ground bonding must be done "right" or the typical hybrid/GT inverter will fault... I did not see any reference on how this product would behave with L1/L2 floating AC outputs (on a quick read):

    http://www.easunpower.com/Products/Off-Grid/5000W_Parallel_Inverter/93.html (yours?)

    Transformers add cost and complexity, as well as some additional losses--It does not usually make a lot of sense to try and "converter" a non-North America inverter to a North American grid connection (and it may not be to code either).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mrfcc1
    mrfcc1 Registered Users Posts: 2

    Bill. Thank you for your comments, yes link for the inverter you have is correct one except for mine is not the #II. system will not be Feeding power back to the grid only drawing from it.  I will be utilizing a 50A 5500 Watt Automatic Transfer Switch #SP-TS4500PLUS  by Spartan Power To automatically switch to the grid when Batteries run low. The inverter was given to me and is new which is why I'm trying to use it.  Yes I am also in US, Northern California thus I have the North American power. The inverter has ground, line and neutral in and out, which is why I will need the transformer

  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    A friend of mine has been going to (and now online) equipment auctions where he has gotten some very good deals on isolated (two sets of windings) transformers (step up or step down for 120/240/208/480 VAC etc.) from machine shops.

    A 5 kVA 120/240 VAC transformer on Amazon is around $1,000.... I am sure you are looking for a less costly option...

    I am not in the industry--So I cannot really give you much guidence--But here is a nice catalog about Buck-Boost and AutoWound transformers:

    https://www.hubbell.com/acmeelectric/en/Catalog (other transformers)

    Perhaps the above link(s) may help... Or you an call them and get some sales help.

    There are just so many design issues with Transformers, I just don't want to lead you down the wrong path.

    Perhaps some other folks here can help...

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    The hassle of a transformer that "might" work, is not worth the effort for what it would have taken to do it right and not jury-rig it.
    But it's your investment.  If you know intermediate electricity and transformer theory, you can dig one up.  But i can't teach you 2 years of electronics over the keyboard.   we can point to ready made off the shelf transformers, but they are pricey.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

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  • jakobw
    jakobw Registered Users Posts: 19 ✭✭
    If you're looking for some commercial options specifically designed for this, Victron has a couple options. 7.6kVa.

    "Autotransformer - Victron Energy" https://www.victronenergy.com/autotransformers/autotransformers

    Solar Edge has a 5kVa option as well. SEAUTO-TX-5000 

    "SolarEdge SEAUTO-TX-5000 Transformer | Northern Arizona Wind & Sun" https://www.solar-electric.com/solaredge-seauto-tx-5000-auto-tranformer.html