traditional stepup or autotransformer for 'split phase'

[Nitrous]

Hi folks,

I'm in the process of winding a 120vac to 240 volt 'split phase' transformer but on further thought, I wonder if a better way might be to use an autotransformer.

I have a 120vac inverter that I'd like to split into 120v - N - 120v split phase.  Is an autotransformer the better way to go, or is a standard primary/secondary CT transformer.  If this is relevant, I'm using a toroidal core.

For that matter, since at this point I'm likely just wanting to offset AC electricity to PV, would a simple step up be best since it would be able to isolate as well as step up...  I just thought I'd ask those who likely know


Thanks
Doug

[richard.cs]

Is there a reason you are winding one rather than buying one? Especially a torroid, hand-winding those for low frequencies is a horrible job.

This doesn't sound like an application needing isolation, so an autotransformer would be a good plan, smaller for the same power, or lower impedance for the same size. A 1:1 isolating transformer could also be used as an autotransformer here.

What power rating do you need?

[Ian.M]

Unless you know for certain your inverter has a grounded Neutral, or that grounding its Neutral is permissible, you need a real transformer, 120V to 120V-0-120V

[richard.cs]

Ah yes, I'd forgotten a lot of smaller inverters effectively give two phases at 60V, (and sometimes with the centre voltage DC offset 80V above battery ground, urgh). If you have one of those then an isolating transformer is needed to create a conventional supply. Can you post your inverter model number or a datasheet?