Simple minded question regarding this from the manual:
2.7. Sizing Limitations
The Autotransformer comes in two models, a 32A model and a 100A model. This value is defined in the amount of current there can be in pass through, so in other words the current which is forwarded without being converted. The transformer itself is equal in both models and has a 32A capacity (peak) and 28A nominal. This is the maximal current that can be used to transfer energy from leg to leg or from 120Vac to 240Vac.
Does this mean that only 28 amps of 240 volts are available and that the remainder of the pass through will be at the inverters 120 VAC?
There are three distinct ways to use the autotransformer.
Step-up, step-down, and balancing.
In step-up (120 to 240V only), you can put up to 28A continuously into the Neutral and L1, and get out 14A at 240V.
In step-up producing split-phase 120/240V, the neutral is both an input and an output. The 100A version will let you pass much more current through on L1, as there is a direct path that does not go through the coil.You won’t get more than 14A out of L2 however.
In step-down (240 to 120 only), you are limited to 28A at 120v continuously (14A at 240v).
If you are doing step-down 240v to split phase 120/240v, the 100A version lets you pass much more current through at 240V as there is a direct path that does not go through the coil. The L1/L2 imbalance still must have less than 28A continuously on the neutral.
Balancing is similar to step-down split-phase, but the input neutral is not connected to the AT. It is critical that stacked 120v inverters have their neutrals connected together, however.
Generator balancing just does not connect the Neutral.
Hmmm, so I made a big mistake buying the Victron Quattro 10kw 120 volt because my vendor told me I could use the autotransformer to handle my 240 vac loads. As contemplated they are an HPHW, a single mini split, a 1.5 hp table saw and someday an EV charger. Not an EE here nor am I capable.
OK, you are in a step-up configuration, 120V → 120/240V split phase.
You can use an autotransformer with a single 120V Quattro to support 240V loads. This is a definitely a supported configuration, but it isn’t ideal. The vendor should have told you the current limitation of the AT.
How many amps for each of those 240v loads?
Do any of them exceed 3360W?
I expect the HPHW and mini-split won’t exceed the limit, but maybe if they are running at the same time. Table saw is intermittent, you can probably use the full 32A (16A 240V) for brief runs. EV charger requires serious 240V power.
Yes, thank you. I bought the inverter in an emergency because of a catastrophic failure of both of my VFX 3524 inverters. Since none of the Outback stuff is supported anymore I began a migration to Victron. Remainder of Victron items are ordered. I should have done my due diligence. The saw is intermittent, only 1.5 hp, hobby stuff, non- pro ( past that) EV charger is a future dream. May be best to build a separate system for that. So if I wire direct from the Victron Auto transformer to my existing AC panel (completely off grid) I can use maybe 3 double pole 15 amp breakers and be sure I do not try to cut wood when also trying to heat water? Or buy another Victron inverter or buy all 120 volt equipment? Easy with Rheme plug in HPWH, also saw motor can be rewired, but heat is a conundrum.
The right answer is to stack two 120v 10k Quattros for full split-phase.
However, buying another 10k Quattro is a lot of money.
Are you off-grid? If so, and you go the Autotransformer route, you have to run {L1, L2, N, G} to the panel, with the neutral coming from the autotransformer.
If you are on-grid, and want to charge batteries via the quattro, you will have a problem as the grid-neutral and autotransformer neutrals should not be connected. The autotransformer would be in parallel with the grid transformer. This is another disadvantage of an autotransformer in on-grid split-phase setups.
You are kind to reply with both good and hard hear advice. Another quattro is $ 2500+ But the AT is about $600, so there’s that. And I have already committed to go blue on the balance of system. Also I have only 10 kw in PV, but to use 20 kw of inverters? hmm Guess I could put 2 of them on the floor. But I truly got a hernia getting the first one up in the air.
