User Manual

GAMMA instabus
Technical Product-Information
April 2021
Power Supply Unit N 125/02 5WG1125-1AB02
Power Supply Unit N 125/12 5WG1125-1AB12
Power Supply Unit N 125/22 5WG1125-1AB22
1 / 4
Siemens Schweiz AG
Smart Infrastructure
Global Headquarters
Theilerstrasse 1a
CH 6300 Zug
RS-AB
© Siemens AG 2021
Subject to change
Update: http://www.siemens.com/gamma-td
Product – and Applications Description
The power supply unit provides the system power neces-
sary for KNX. The connection to the bus line is established
via the bus connection block located on the front side.
The integrated choke prevents the data telegrams from
short-circuiting on the bus line. When the built-in reset
switch is operated (operation > 20s), the bus devices are
returned to their initial state.
For each bus line, at least one power supply unit is
needed. Up to two power supply units may be attached to
a single bus line. A second unit is not required unless the
supply voltage at a bus device is less than 21 V.
Note: If two power supply units N 125/_2 are operated in
parallel on one bus line and if the overload LED is lit on
one or both power supplies, then the bus configuration
has to be changed until the overload display disappears.
Two devices of the same type can be connected di-
rectly in parallel to double the current required for a
line. No minimum bus cable length is required
between the two KNX power supplies.
When more than 30 bus devices are installed in short bus
cable distance (e.g. 10 m), e.g. in distribution boards, the
power supply unit should be arranged near these bus de-
vices. The distance between power supply unit and any of
its bus devices must not exceed 350 m.
The power supply unit has a voltage and current regula-
tion and is therefore short-circuit proof. Short power fail-
ures can be bridged with a backup interval of approxi-
mately 200 ms.
To ensure an uninterrupted power supply a separate cir-
cuit with safety separation should be used for the power
supply unit power supply line.
The power supply units can supply DC 24 V power from an
additional pair of terminals (yellow/white). This DC 24 V
output voltage can be used to power e.g. an additional
line via a separate choke N 120.
The power supply units N 125/_2 can be powered by
AC 120…230 V or by DC 220 V.
More information www.siemens.com/gamma-td
Example of Operation
8 9
RESET
Betrieb/ON
Über last/ Overload
5WG1125- 1AB22
N
+ -
L
+ -
N
L
PE
KNX +
KNX -
DC +
DC -
s