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Siemens
Desigo TRA Engineering, mounting and installation
CM111043en_09
Building Technologies
Important information on safety
2016-02-22
Spikes and high-frequency interference may occur in areas with high levels of
interference. The disturbances not only impact the transformer on the primary side,
but may also influence secondary connected components.
A mains filter should be attached on the primary transformer if such interference is
anticipated. Mains filters should be installed as close to the network transformer as
possible and grounded.
Peak loads occur when switching inductive loads that may cause faults to the
system. In addition, sparks may damage switching contacts. Power components
must include effective protection against disturbances to prevent such faults.
Inductivity (transformers, fuses, relays) are wired directly at the terminals using
transzorbs, MOVs (metalloxyd varistors) or RC elements. The breakdown voltage
of the transzorbs or MOVs must equate to the 1.7 to 2 times the applicable nominal
voltage.
Inductive DC consumers can also be suppressed using diodes or RC elements.
The transzorbs, MOVs, diodes or RC elements must be optimally matched to the
power components and mounted using short wiring.
3.2 Device-specific
regulations
Devices must have the required insulation of the power circuits from each other to
be able to connect them directly without additional insulation.
Connections via interfaces increase the risk of distributing dangerous voltage
through the building. Ensure that the required insulation is available at all times and
installed per applicable regulations.
The terminals for the supply of additional devices
(terminals 7 and 8) bare a max current of 6 A.
An external T 10 A fuse is compulsory
The island bus conductor V~ is fused with the T 10 A fuse in the PXC3 / the power
supply module. The cross section of the field device cables must therefore be
designed for 10 A.
IEC: Fusing with max. 10 A
NEC: A class 2 transformer or an external T 4 A fuse is compulsory
Max. 100 VA per transformer / per fuse circuit
System neutral ( ) must always be grounded at the transformer.
Max. load. 6 A for the supply lines (protection of the PCB tracks to the load
circuits / relays).
Mains filter
Emergency
intervention of power
components
Field device connection
Devices using different
power circuits
Interfaces for different
voltage circuits
PXC3...
supply AC 24 V
TX-I/O modules: island
bus conductor V~
(AC 24 V)
DXR2... with supply
AC 24 V
DXR2
.M
... with supply
AC 24 V
DXR2... with supply
AC 230 V
