2. Introduction
2.1. Description
The Victron Energy Autotransformer (AT) supports many different wiring configurations. It can increase your system’s ability
to adapt to different design and Voltage requirements, and also be used to balance loads in split-phase 120/240Vac systems.
Specialty systems such as boats and vehicles may face different shore configurations while traveling, an autotransformer can
help by being flexible and enabling connections to most grid configurations.
The Victron Energy Autotransformer has the ability to use a ground/earth relay to create a Neutral to Ground bond in the AT itself,
if coupled with a Victron Energy MultiPlus or Quattro and the relay terminals are interconnected.
This manual will explain the many uses for this device and how to safely install and wire it. Below there are general examples
of four ways the Autotransformer can be applied. There are several specific uses that can be realized in the integration of
an autotransformer into an installation and are explained in section 2.4. The AT does not provide isolation. See section 4 for
specifications.
2.2. Models
• 120/240V - 32A
• 120/240V - 100A
Pass through current is 32A and 100A respectively, the transformers are 100% equal in both models. See more information in
section 2.8.
2.3. Types of Use
2.3.1. Balancing
Balancing a Generator or Stacked Inverters
Full power from a split phase supply source such as a generator or stacked inverters is sometimes limited, as a single phase load
cannot draw more energy than its individual leg will allow even though the other leg isn’t fully utilized.
If balancing a generator or stacked inverters is required, the AT can accomplish this by leaving the neutral of the split
phase supply unused, to create a new neutral, as shown in the illustration below. Any load unbalance is “absorbed” by the
autotransformer.
The two legs of a split phase from an AT are independent from each other, beside the fact there is a fixed phase shift between
them. This (180Deg) phase shift means the sine-wave of both legs is in full opposite (creating a double voltage from leg to leg
rather than that of leg to Neutral).
With an AT, energy from one leg can be “transferred“ to the other leg which creates a far higher total load level, unlocking the full
potential of power available from a generator or stacked inverters..
Victron Energy Autotransformer
Page 2
Introduction
