The power supply unit (100) is designed

• to isolate the voltage supply using a main switch,
• to distribute the voltage and safeguard the power elements such as fans,
• and to generate and protect the control voltage.

The control voltage must be generated by a control transformer with separate coils in accordance with EN 60204-1:2006 subclause 9.1.1.

The failure of the voltage supply for the power supply unit or switching off the power supply unit will generally result in a fault lock-out of the equipment (see EN 746-2:2010 subclause 5.7.4).