Central Bus Power Supply - Siemens RXB Series Basic Documentation

Introduction
Note
Power supply unit PSU
Siemens power supply
units
Note
20 / 88
Siemens
Building Technologies
2.2.3

Central bus power supply

When one or more power supply units (PSU) are used for the bus power supply,
this is referred to as a "central bus power supply". This type of bus power supply is
required in the following circumstances:
The max. allowed 8 Synco devices with DPSU (Decentral bus power supply =
On") is insufficient to cover the power consumption of the devices without a bus
power supply.
Synco devices and third-party devices are installed on the same line.
Only devices without a bus are installed on the same line.
On a line with a central bus power supply, the following devices must not be used
to supply power to the bus:
RM... controllers
OZW775 central communication unit
QAX9x3 central apartment unit
These Synco devices must be set to "Decentral bus power supply = Off" to prevent
them from interfering with bus communications.
At present, power supply units for 160, 320 und 640 mA are available. The power
requirements of the devices must be calculated as a means of determining the
required power supply unit, PSU See the relevant values on the previous page.
For a line with 64 bus devices, each with a power consumption of 5 mA (64 x 5 mA
= 320 mA), a PSU of 320 mA is sufficient.
For KNX networks, the following PSUs by Siemens are recommended.
Order types:
5WG1 125-1AB02, short code N125/02
5WG1 125-1AB12, short code N125/12
Product data:
Operating voltage AC 120...230 V, 50...60 Hz
Bus voltage output
For KNX networks with IP routers, the following Siemens power supply unit is
recommended:
Order type:
5WG1 125-1AB22, short code N125/22
Product data:
Operating voltage
Bus voltage output
Auxiliary voltage output for IP router
For further information see the product description and description of functions
(enclosed with the device) or under:
A DC 29 V voltage with choke is required for the bus power supply. The DC 24 V
auxiliary voltage for the IP router requires a voltage source without choke.
KNX bus communications
Engineering notes
160 mA (with integrated choke)
320 mA (with integrated choke)
DC 29 V (21...30 V, with choke)
640 mA
AC 120...230 V, 50...60 Hz
DC 29 V (21...30 V, with choke)
DC 24 V (12...30 V, without choke)
http://www.siemens.com/knx-td
For internal use only
CE1P3127en
2013-04-08