The Victron 120/240V 100A Shore Power Split Phase Autotransformer (ITR000100101) from Nomadic Supply Company is a transformer for step-up, step-down, and split-phase output balancing purposes. The step up and step down part is easy: Input can be 120 Volts and output 240 Volts or input can be 240 Volts and output 120 Volts.
Regardless of the input voltage, the input current is limited by the built-in breaker to 100 Amps. The split phase output balancing is a bit more complicated to understand: When the input is 240 volts you can have two 120 volt load groups with a total output of the full 100 Amp rating regardless of whether the loads are balanced or not. The transformer automatically takes care of the load balancing.
Consider for example a 30A 120/240V split phase supply. The supply could be the grid, a generator or two stacked inverters. Some of the loads connected are 240V, others are 120V. On each 120V leg the load should not exceed 30A. The problem is that as soon as 120V loads are connected, the two legs will show a different current. This is because the 120V loads on the two legs will never be balanced. A 120V 1200W hairdryer, for example, will draw 10A from one leg. A 120V washing machine could even draw in excess of 20A from one leg. Between the two legs the difference in current, or current unbalance, will therefore often be 20A or more. This means that the 30A supply will not be used up to its full potential. By the time one leg draws 30A, the other leg may be drawing no more than 10A, and increasing the 240V load, for example, will result in an overload of one leg while the other leg still has spare capacity. Theoretically, the total power that can be drawn from a 30A 120/240V supply is 30 x 240 = 7,2 kVA. In case of 20A unbalance, the practical maximum will be 30 x 120 + 10 x120 = 4,8kVA, or 67% of the theoretical maximum. The solution is an Autotransformer. By leaving the neutral of the split phase supply unused, and connecting an Autotransformer to create a new neutral, as shown in figure 1, any load unbalance is ‘absorbed’ by the Autotransformer. In case of a 30A supply, the load can be increased to 7,2kVA, and a 20A load unbalance will result in one leg supplying 40A, and the other leg 20A. The 20A difference will flow through the neutral and the windings of the Autotransformer. The current through both 120V wires of the split phase supply will be 30A.
Temperature protected In case of overheating, the Autotransformer is disconnected from the supply. Reset is manual. Ground relay for use with Multi or Quattro Inverter/Chargers included When operating in inverter mode, the neutral output of the inverter/charger must be connected to ground to guarantee proper functioning of a GFCI. In case of a split phase supply the neutral must be grounded. For this purpose, a grounding relay is Built-in the autotransformer’s enclosure. The relay is controlled by the 230/240V Multi or Quattro. (The internal grounding relay in the 230/240V Multi or Quattro must be disabled)
Victron 120/240V 100A Shore Power Split Phase Autotransformer (ITR000100101) Specifications:
- Autotransformer 100 A
- Input/output voltage 120 / 240V
Input circuit breaker 100 A two pole - Frequency 50/60Hz
- 240V to L1,L2 current 32A
- Neutral current, 30 min 32A (3800VA)
- Neutral current, continuous 28A @ 40ºC/100ºF
- Transformer type Toroidal
- Enclosure Aluminium
- 100 Amp Input circuit breaker included
- Protection category IP21
- Safety EN 60076
- Weight 13.5 Kg
- Dimensions (h x w x d) 425 x 214 x 110
Victron 120/240V 100A Shore Power Split Phase Autotransformer (ITR000100101) Documents:
Victron 120/240V 100A Shore Power Split Phase Autotransformer (ITR000100101) Datasheet
Please contact Nomadic Supply Company for returns, repairs or support issues related to your Victron product.