An Autotransformer is an electrical transformer with only one winding. The winding has at least three electrical connection points called taps.
Single Phase Vari-O-Stat takes the input from 240 V - 50 Hz AC line and the output can be varied from 0 - 270 V. Single phase Vari-O-Stat are available in projection Mounting and Flush Mounting types. For better cooling, Vari-O-Stat of rating above 30 amps are made in oil - cooled construction. Output of these Vari-O-Stat can be varied from 0 to 270 V input being 240 V - 50 Hz AC.