Isolation transformers are used to prevent dangerous situations caused by simultaneously touching a faulty device and a part connected to the ground for example in the case of an insulation fault. A isolation transformer enables the creation of galvanic separation between the supplying and supplied circuits. Isolation transformers are defined in standard EN 61558. Its nominal primary voltage can be a maximum of 1000 Vac and the primary voltage a maximum of 500 Vac, or 708 Vdc when equipped with a rectifier.
The operating principle of a isolation transformer: