The power supply modules are inserted at the far left in the rack (starting from slot 1). Depending on the version, they occupy slots 1 to 3. The modules are enclosed and are cooled via natural convection.

The front of the module contains:

• LED displays:
  LEDS indicate internal faults, correct output voltages 5 V DC, 24 V DC, and correct back-up battery voltage.
• Pushbutton for fault acknowledgment.
• On/off switch for output voltages.
• Battery compartment for back-up battery (batteries).
• Switch for battery monitoring.
• Supply voltage selector switch (not for wide-range power supplies).
• Power supply connection.

The back-up battery is optional and must be ordered in addition. For power supplies at and above 10 A, two back-up batteries are recommended.