logo specialtrasfo


Transformers for MV Drives and Converter applications

Capacity up to 90 MVA;
AC primary voltage up to 175 kV;
Frequencies up to 400 Hz;
Multi-pulse topologies available: up to 36-pulse in a single unit;
Electrostatic shield between primary and secondary windings;
Off-Circuit Tap-Changers available.

Designed to meet all types of environmental conditions:
extreme temperatures, from -50°C to +55°C;
altitude, over 4000 m asl;
corrosive atmospheres;
seismic zones;
hazardous areas.

All cooling system types available, by means of mineral or less-flammable fluids, air or water external cooling mediums, natural or forced circulation.


We manufacture rectifier transformers for D.C. motor drives and for excitation of medium or large generators. In this case the rectifier circuit most frequently used is the three-phase bridge, 12-pulse arrangement. The latter is achieved by two transformers (usually in the same tank), whose secondary voltages are displaced in phase to each other by 30°.


It is possible to obtain this displacement when one transformer is star-star or delta-delta connected and the other one is star-delta or delta-star connected. One transformer only may be sufficient if it is designed with two secondary windings, one in star and one in delta connection.