The combined transformer rectifier creates an extremely robust DC power supply. These products are designed to be briefly overloaded, without immediately tripping an overcurrent protection device. Because they make no use of electronic controls there is no risk of instability with more complex load profiles. This makes them ideal for applications where high peak currents occur, for example when starting up DC motors or when large numbers of magnetic contacts are triggered.
A three-phase supply is used from 700VA upwards (our TGT series). The advantage is that the current ripple is very low after three-phase rectification. No electrolytic condensors need be used, thus extending the service life of the product.