Page 117 - Basic Course

KNX BASIC COURSE

21 Power supply unit with data rail

DVC DVC
>= 21 V DC >= 21 V DC
TP Connectors

Connection with
screwless terminals
Bus line

Spring contacts

230 V
50/60 Hz
PS +
Bus + DIN Rail with data rail
Bus ‐
PS ‐
Connector
Power supply unit Choke
30 V DC 640 mA
> 100 ms buffer
Figure 20: Power supply unit (on DIN rail with data rail)

The above figure shows the bus connection of the power supply unit connected via spring
contact blocks to the printed conductors of the data rail. This type of connection i.e. the
standard data rail glued into the DIN rail can be found in old installations. The bus cable is
connected to flush mounted bus devices via a 2-pole data rail connector.

Home and Building Management Systems KNX Association
KNX TP Installation Installation_E1213c 27/28