Danfoss AK-PC 781A, User Manual, Page: 40 / 138

40 Capacity controller RS8HE202 © Danfoss 2017-07 AK-PC 781A
Supply voltage
Supply voltage is only connected to the controller module. The
supply to the other modules is transmitted via the plug between
the modules.
The supply must be 24 V +/-20%. One power supply must be used
for each controller. The power supply must be a class II.
The 24 V must not be shared by other controllers or units. The
analog inputs and outputs are not galvanically separated from the
supply.
The + and – 24V input must not be earthed.
If using stepper motor valves, the supply for these must be pro-
vided from a separate power supply.
For CO2 facilities, it will also be necessary to safeguard the voltage
to the controller and valves using UPS.
Power supply size
The power consumption grows with the number of modules used:
Module Type Number á Effect
Controller 1 x 8 = 8 VA
Extension module 200 series _ x 5 = __ VA
Extension module 100 series _ x 2 = __ VA
Total ___ VA
12
Example continued:
Controller module 8 VA
+ 2 extension modules in 200 series 10 VA
+ 2 extension modules in 100 series 4 VA
------
Power supply size (least)
22 VA
Common pressure transmitter
If several controllers receive a signal from the same pressure trans-
mitter, the supply to the affected controllers must be wired so that
it is not possible to switch off one of the controllers without also
switching off the others. (If one controller is switched off, the sig-
nal will be pulled down, and all the other controllers will receive a
signal which is too low)