question

GeorgeV avatar image

Autotransformer output not 120v

Hello. Is my brand new 100a autotransformer defective?! It is putting out 120v and 114v on each leg.

Can I fix this? What do I do?

voltageAutotransformer
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1 Answer
Johannes Boonstra (Victron Energy Staff) avatar image

Hello, firstly, what is exactly the problem if the balance isnt 100% equal?, due to current unbalance between the legs this is often created. a few % difference will not cause any issues for loads connected Beside this, how are you using the AT ?

As step up/step down or as load balance?

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I am having the same issue - 114V on L1 and 120V on L2

120V current is supplied by a Quattro 48V / 10000 / 140-100/100 to the 100A Autotransformer. I'm using the AT to provide a split-phase 120/240v supply to the 50A main break panel in my RV

I have wired the AT connections according to the diagram #3 shown on the system schematics page from the Victron website: (https://www.victronenergy.com/upload/documents/AT-3-split-phase-120V-to-120-240V-with-Quattro-120V.pdf)

The Ground Relay in the Quattro is set to ON and is correctly grounding the Neutral to earth.

Here are the voltages I read at the terminals:


The problem I have with this is that the voltage on L1 decreases a lot with load, and when occurs equipment will pull more current to compensate for the lower voltage.

Here is a pic of my RV control panel, showing the disparity in voltage between L1 and L2. Even though there are 2 air conditioners on L2 it has only dropped 2 volts - L1 dropped from 114v to 105v. This can't be good.


Question - Is this method of wiring correct, and if so, what is causing the voltage discrepancy?

Thanks!

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