An isolation transformer is one where the primary and secondary windings are separate, as opposed to an autotransformer where the primary and secondary share a common winding.
The isolation transformer will offer you several advantages listed below:
- Ensures consistent control voltage, as it is derived from 2 phases, rather than a phase and a neutral
- Since primary is isolated from secondary; any disturbances on main line is not reflected on control voltage
- Disturbances like welding, lightning will not damage equipment
- Ultra isolation is available for very sensitive equipment