AutoTransformer - Balancing Loads - And Motor Startups?

[MrM1]

A few years about I installed an Outback x240 Autotransformer to my Conext SW4024 4000w Split Phase 120vac/240vac Inverter. I did this for balancing loads between L1 and L2 because the SW has a Grid Interactive / Grid AC Support Mode that "Supposedly" draws from the battery for loads over 2amps. It was supposed to draw from the grid only for loads under 2 amps, but it never really worked well for unbalanced loads on either L1 or L2 unless it was a big load. At 300-600 watts it mostly just draws off the grid, BUT ... if that load was balanced across L1 and L2, the more balanced you could get the load, the better AC Support Mode worked.

I put the Outback x240 in as shown below (except the SW is a single L1/L2 240vac inverter and NOT 2 Outback 120vac inverters).



It works much better now with the Autotransformer. 120vac loads are more consistently balanced across L1 and L2, and the AC Support mode works better too.

BUT ... I was reading recently that an AutoTranformer may actually cause the Inverter to run at a higher idle state. I think the SW draws about 11 watts from the battery bank just sitting there.

Is an Autotransformer actual hard on the Inverter transformer?

Does the Autotransformer make it harder or easier to start a 120vac motor? A 240vac motor?

Is the Autotransformer doing me more harm than good over the long run for the SW's Inverter Transformer (ie. is it damaging anything - shortening the life)?

 

[Bud Martin]

Transformer will draw idling current. Just do the search for 'transformer idling current'.

 

[MrM1]

I guess my main question is does it make it more difficult for a 240v well pump motor to start up? Or rather is it harder on the inverter with the AT on?