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Siemens
Desigo TRA Engineering, mounting and installation
CM111043en_09
Building Technologies
Wiring of power lines
2016-02-22
6.4
Power supply for field devices
Most of the TRA devices have a built-in power supply for field devices
Type
TXM1.8U
DXR2.x09
AC 230 V
DXR2...
AC 24 V
DXR2.x18
PXC3
RXM39.1
Data sheet
N8173
N9204
N9206
N9205
N9207
N9205
N9207
N9203
N3836
AC 24 V
48 VA
5)
4 VA
2) 3)
12
VA
18 VA
48 VA
6 VA
Fusing
10 A
4)
1)
1)
1)
10 A
4)
1)
DC 24 V
2.4 W
Fusing
1)
KNX field supply
(terminals 3 and 4)
48 VA
Fusing
1)
1)
Short circuit proof.
2)
Sum of all triacs plus field supply
3)
Air quality sensors (QPA.., AQR..) and condensation monitor (QXA..):
These devices require an external / local transformer.
Reason: Although the documented continuous load is only 0.5 VA, high peak
currents occur at switch on and during measurement operations.
4)
T 10 A fuse in the PXC3 / in the power supply module / in the bus connection
module.
Use cable cross section suited for
10 A
according to local regulations!
5)
TXM1.8U: Bus connection module may feed any supply voltage.
Field devices may be powered using an external / local transformer.
The external transformer must NOT be grounded (earth loops).
The external power supply must NOT be used to supply the triacs.
N1
Room automation station
Y1
General device with input
DC 0...10 V, supplied by room
automation station
Y2
General device with input
DC 0...10 V, supplied externally
External supply must NOT be
earthed (earth loop)
Y3
General device with input
DC 0...10 V, supplied externally
External supply must NOT be
used to supply the triacs
Y10
Y10
11
0
43
z4
1
N1
N1
Y2
Y3
V
V
V
Y1
AC 24 V AC 230 V
Y10
N1
V
V
AC 24 V
AC 230 V
Y4
0.
.1
0
V
O
U
T
T
ria
c
24
V
Note!
Caution!
Note!
Powering field devices
with external transformer