1
Hauptschalter
40A
63A
80A
ein- oder mehrdrähtig
mm²
16
16
50
feindrähtig
mm²
16
16
35
© STULZ GmbH – all rights reserved EN/04.2021
electrical options
11.5 Electrical Options
11.5.1 Second Power Supply
This option provides the connection of a second power supply. Both power supplies are switched on to the
A/C unit by two main switches. An internal circuit ensures that the priority is set on power supply 1.
All three phases of both power supplies are checked constantly on excess voltage, undervoltage, phase fai-
lure, phase balance and correct rotation. In case of failure of supply 1 the unit is switched off. After a lapse of
time which can be set at the time relay (preadjusted: 10 seconds) power supply 2 is switched onto the unit. The
unit starts by the automatic restart which is integrated in the controller.
When the voltage of power supply returns, the unit is switched off again. On a second time relay a delay can
be set (preadjusted: 10 seconds), after which power supply 1 is switched onto the unit. The unit starts by the
automatic restart.
Requirements:
• Network configuration TN-S, TN-C-S (400V +/-10%, 3 phases, N,
PE, 50/60 Hz)
• Use only copper conductors for 75°C.
• Install two pre-fuses in the supply lines.The size of the pre-fuses
depends on the terminal equipment (A/C unit).
• Choose the cable cross-sections in accordance with local standards,
the laying method and line lengths.
Maximum cross-section of the supply lines
Main switch
single-wire or multi-wire
mm²
finely stranded conductor
mm²
