Parallel Victron 100 amp auto transformers?

[Uoavitar]

I have a question for you.

Can I parallel two Victron 100 amp auto transformers to get higher capacity?

I have and Onan 5500 watt 110v single phase generator feeding into one Victron 100 amp Auto transformer right now that then feeds into 2 10k Quattros to make split phase output.

The problem is even on the lowest AC input setting on the Quattros it's pulling enough current through the Auto Transformer to trip the thermal side of the built in breaker.

 

[justinm001]

I thought you can just disable switch as group and use 110v input on one Quattro but still feed for split phase output. 5500w is well below the 100a input limit.

 

[HighTechLab]

The autotransformer is only rated for 32A of current - the breaker is larger to supply a higher feed-through current (for 240v loads as an example).

I would NOT parallel two of these transformers, as they could have slightly different windings and "fight" each other.

@justinm001 is on the right track - I would do that.

 

[Uoavitar]

justinm001​

I think you solved this for me. I kinda had a "Duh" moment after reading your reply.

Instead of me running all the generator power through the auto I should hook one Quattro #1 straight to the generator out and only run the spilt phase Quattro #2 through the auto. That will cut the power going through the auto in half. I'll have to try this after I get back from camping.

 

[justinm001]

Awesome let us know how it works out

 

[Hedges]

justinm001​

I think you solved this for me. I kinda had a "Duh" moment after reading your reply.

Instead of me running all the generator power through the auto I should hook one Quattro #1 straight to the generator out and only run the spilt phase Quattro #2 through the auto. That will cut the power going through the auto in half. I'll have to try this after I get back from camping.

Uh, mind sketching a schematic of what you mean?
And sketch a schematic of what you were thinking of before?

One of the Quattro was never going to have its power go "through" the autotransformer. It was only going to be wired in parallel. I think it still is.

?

If the 10k Quattros does what my Sunny Islands do, no need for a transformer.
120VAC in passes through one inverter, which charges battery.
Other inverter makes 120VAC 180 degrees out of phase for split phase. (or two others make 120 and 240 degree out of phase for 120/208Y 3-phase.)

If you do want a higher wattage auto-transformer, look for a used 240/480 to 120/240V utility transformer.

You can wire the two 240V primary windings in series (240/480) and use them for 120/240V. At rated current, reduced wattage.

Alternatively, wire primary in parallel (240 || 240), wire secondary in series (120/240), wire secondary in series with primary. Feed 120V to primary and you get another 120V off the 240V secondary. Secondary will be about +3% in voltage no-load, sags to -3% under load.

This will be much better behaved than either applying rated 240V to 240V primary, or applying voltage to secondary.

 

[justinm001]

Uh, mind sketching a schematic of what you mean?
And sketch a schematic of what you were thinking of before?

One of the Quattro was never going to have its power go "through" the autotransformer. It was only going to be wired in parallel. I think it still is.

?

If the 10k Quattros does what my Sunny Islands do, no need for a transformer.
120VAC in passes through one inverter, which charges battery.
Other inverter makes 120VAC 180 degrees out of phase for split phase. (or two others make 120 and 240 degree out of phase for 120/208Y 3-phase.)

If you do want a higher wattage auto-transformer, look for a used 240/480 to 120/240V utility transformer.

You can wire the two 240V primary windings in series (240/480) and use them for 120/240V. At rated current, reduced wattage.

Alternatively, wire primary in parallel (240 || 240), wire secondary in series (120/240), wire secondary in series with primary. Feed 120V to primary and you get another 120V off the 240V secondary. Secondary will be about +3% in voltage no-load, sags to -3% under load.

This will be much better behaved than either applying rated 240V to 240V primary, or applying voltage to secondary.

Op has 110v gen input so was using the autotransformer to convert that to split phase for both quattros input. Problem is he needs over 20a on each leg minimum which is more than the 32a total the autotransformer can handle.

On the quattros when you configure them for split phase there's a checkbox to switch as group so if only getting power on 1 leg it'll reject the input. Disabling this option like I stated allows him to do what you're saying, use 110v in on one inverter then the other will pull from the battery split phase. This way he'll have 110v in but 240v out and will be able to pull 40+ amps from the 110v which is well above the 20ish amp minimum input.

I have the 5000w quattros and my min is 13ish amps so I'm assuming his is double. Although the v506 firmware allowed me to set it to 8a but then sometimes changed it to 13a.