interISOLATE isolation transformers are used to galvanically separate a device connected to the secondary side from the supply current, which prevents electric shock between the earth and the phase. For safety reasons, isolation transformers should always be used when repairing electrical devices.
Isolation transformers have galvanically separated primary and secondary coils. Isolation transformers are often also called intermediary transformers or control voltage transformers. Typical transformation ratios include 230/115V, 230/230V, 400/230V or vice versa.