THREE PHASE TRANSFORMER

[MIKE31 0]

HI EVERYONE What is the difference between regular step down 3 phase transformer with step down three phase auto transformer and what are the application. Thanks

[panic mode 246]

Both are used to step down the voltage but the autotransformer does not offer isolation (secondary is actually tap on the primary coil). This does reduce size, weight and of course the price (which is great). The biggest limitation is that it cannot be used in applications that require isolation. The closer primary and secondary voltages are, the smaller size of the autotransformer - because it is only used to produce the difference in voltage. This difference is then added (step up) or subtracted (step down) from primary voltage - hence no isolation.