Victron Autotransformer 120/240V 50A: High-Capacity Voltage Conversion and Split-Phase Load Balancing

The Victron Autotransformer 120/240V 50A is a high-capacity solution for systems requiring voltage step-up, voltage step-down or split-phase load balancing. Designed for specialist mobile, marine and off-grid power systems, it helps adapt AC power from a generator, shore power connection, inverter or stacked inverter system to suit your installation.

With a toroidal transformer and up to 50A feed-through capacity, it can convert between 120V and 240V AC configurations while helping maximise the usable power available from a 120/240V split-phase supply with uneven 120V loads.

Maximise Split-Phase Power with Load Balancing

In a 120/240V split-phase system, 120V loads are rarely distributed evenly across both legs. A large load on one leg can cause it to reach its current limit while the other leg still has unused capacity. This can restrict the total power available from your generator, grid supply or inverter system.

The Victron Autotransformer creates a new neutral point, allowing load imbalance to be absorbed by the transformer. This helps transfer available energy between the two 120V legs, allowing greater use of the full capacity of the split-phase supply.

The 50A model supports up to 55A of neutral current for 30 minutes and 45A continuously at 40°C, making it ideal for larger systems where significant 120V load imbalance is expected.

Step Up or Step Down AC Voltage

The Autotransformer can also be configured to increase or decrease AC voltage according to the requirements of the installation. It can step a 120V AC source up to 120/240V split-phase output, or step down a 120/240V supply for use with compatible 120V equipment and inverter systems.

This makes it a practical choice for generators, shore power connections, air-conditioning systems, water pumps and other AC loads where the available supply voltage does not match the required system configuration.

A Flexible Alternative to Stacked Inverters

Where 120/240V split-phase output is required, a single 120V inverter paired with an Autotransformer can be an effective alternative to using two stacked 120V inverters. The Autotransformer creates the required split-phase output while allowing available power to be shared more effectively between the two 120V legs when loads are uneven.

Integrated Ground Relay for Victron Inverter/Chargers

The Autotransformer includes an integrated ground relay for compatible Victron MultiPlus and Quattro inverter/charger installations. When correctly configured and connected, it creates the required neutral-to-earth bond to support the correct operation of GFCI and RCD protection devices.

The relay is controlled by the inverter/charger via its ground relay terminals. Installation and configuration must be completed by a qualified electrician in accordance with the Victron wiring diagrams and applicable electrical standards.

Thermal and Overcurrent Protection

Built-in protection helps safeguard the Autotransformer during demanding operation. When the transformer becomes warm, the cooling fan operates and the red temperature LED illuminates. In the event of overheating or overcurrent, the integrated two-pole circuit breaker disconnects the unit. Once the cause has been addressed, the breaker can be manually reset.

Robust Indoor Installation Design

The Autotransformer is housed in a durable aluminium enclosure with an IP21 protection rating, integrated wall-mounting points and screw terminals suitable for cables up to 35 mm² / AWG 2. It is intended for indoor or protected compartment installation and requires sufficient ventilation around the enclosure.

Please note: This is an autotransformer and does not provide galvanic isolation.

Key Features

• High-capacity AC conversion: Supports 120V to 240V step-up and 240V to 120V step-down configurations.
• 50A feed-through current: Suitable for higher-capacity 120/240V AC systems.
• Split-phase balancing: Helps transfer available capacity between uneven 120V loads.
• High neutral-current capability: 55A for 30 minutes and 45A continuous at 40°C.
• Integrated ground relay: Designed for compatible Victron MultiPlus and Quattro inverter/charger systems.
• Thermal protection: Cooling fan, temperature indication and automatic disconnect protection.
• Overcurrent protection: Integrated two-pole circuit breaker for protection and manual reset.
• Durable construction: Toroidal transformer in an aluminium IP21 enclosure.
• 5-year warranty: Backed by Victron Energy’s limited 5-year warranty.

Technical Specifications

• Input/output voltage: 120 / 240V AC
• Frequency: 50/60Hz
• Input circuit breaker: 50A, two-pole
• Maximum 240V feed-through current: 50A
• Neutral current: 55A for 30 minutes at 40°C; 45A continuous at 40°C
• Transformer type: Toroidal
• Electrical terminals: Screw terminals, up to 35 mm² / AWG 2
• Protection rating: IP21
• Dimensions: 460 x 214 x 110 mm
• Weight: 12.5 kg

Make Better Use of Your Available AC Power

For larger compatible 120/240V power systems, the Victron Autotransformer 50A provides a practical way to adapt AC voltage, manage uneven split-phase loads and improve the use of available generator or inverter capacity. It is ideal where system flexibility, safe neutral grounding and high-capacity load balancing are required.