Powergen, leader in this field, founds its own roots on the work by Mr. Ernesto Borri, industrialist, that patented some equipment since 1940.

Some examples here:

 

1941
Industrial Invention Patent
Electric heater with pedal control and change-over switch for an extensive temperature adjustment.

 

 

 

1952
Industrial Invention Patent
Device for simultaneous electronic control of battery cells on electric storage batteries, in particular for fast battery chargers.

 

 

 

1955
Industrial Invention Patent
Safety step-down transformer which does not absorb current when quiescent. Suitable for low voltage outlets to be installed as an ordinary outlet.