2 The weight and volume of the auto-transformer is less.
3 The auto-transformer has a higher efficiency and suffers less
voltage variation with changing load due to the better magnetic link-
age between the primary and secondary sections of the winding.
Auto-transformers are used to interconnect the 400 kV, 275 kV
and 132 kV sections of the British grid system. When transporting
very large high voltage transformers by road the weight has to be
carefully considered and quite often, before major power system
construction is commenced, roads and bridges have to be specially
reinforced to carry such loads.
It is also worth noting