If neutral is needed in a three-phase network, when to choose an autotransformer to generate artificial neutral and when to choose an isolation transformer?

If a neutral is required in a three-phase network, it is essential to understand when to choose an autotransformer to generate an artificial neutral and when to opt for an isolation transformer.

Using an autotransformer to generate a neutral  (AUTN) converts a three-phase 400V supply into an output with a neutral conductor. Between the neutral and each phase, you obtain a voltage of 230V, which allows you to connect single-phase loads, even if they are not balanced. Even so, the maximum rating per phase is limited to one third of the autotransformer’s total rating.

Regarding to autotransformers, it is important to note that it does not provide galvanic isolation, which means that the neutral generated is floating. If the neutral needs to be earthed, this could cause the earth leakage circuit breaker to trip.