2 isolation transformers for dual power UPSs

2 isolation transformers for dual power UPSs


The company that asked us for a solution is a long-standing Italian customer of Ortea, specialising in uninterruptible power supplies (UPS) for industry.



The customer raised a technically challenging request: to supply a series of UPS transformers with dual power supply intended for the eastern market and therefore with a 60Hz power frequency.



This requirement led to the design of two copper transformers with integrated reactance and a zig-zag secondary, featuring a double delta primary. The zig-zag configuration of the secondary offers a balancing of the phase currents returned to the primary, reducing the risk of imbalances caused by unbalanced loads or disturbances in the power grid. Furthermore, thanks to this transformer configuration, there is an improvement in the power quality at the UPS input, reducing the damaging effects of disturbances and faults in the mains.
The integrated reactance reduces the short-circuit current, protecting the transformer and other system components. In addition, the reactance acts as a filter, reducing harmonics in the mains, i.e. those undesirable frequency components in the electrical waveform that can be caused by non-linear loads in the system. The presence of a reactance can attenuate some of these harmonics.
The main aspect of this technological configuration lies in the choice of two separate delta primaries, linked to the presence of two separate and isolated power sources at the same voltage, which allows the creation of a UPS system with a “dual input” or “dual feed” configuration. In such a power supply system, the UPS is designed to receive power from two power sources and automatically switch between them in the event of failure or interruption of one of the sources. This ensures continuity of power supply to critical loads.
The use of two separate delta primaries may be a specific design choice to accommodate two separate sources, each of which may have slightly different characteristics and parameters. The separation of the delta primaries helps to isolate the two sources, preventing unwanted current flows between them.