Siemens Metro 21 M216KA Operator's Manual page 62

Wiring
Characteristics of
r
Load Current
Power Supplies
Rule: Ground Load
Circuits
EMC
3-6
The load current power supply feeds input and output circuits (load circuits)
as well as sensors and actuators. The following table lists the characteristics
of load current power supplies that are required in specific applications.
Characteristic of
Load Current
Power Supply
Safe (electrical) isola- Modules that have to be
tion supplied with voltages
60 VDC or
24 VDC load circuits
Output voltage toler-
ances:
20.4 V to 28.8 V 24 VDC load circuits
Load circuits should be grounded.
Fault-free operating reliability is ensured by the common reference potential
(ground). Install a detachable connection to the protective conductor on the
external power supply (terminal L or M) or on the isolation transformer (Fig-
ure 3-1, ). This measure makes it simpler for you to locate ground faults in
the power distribution system.
You will find notes on EMC
for the DP master you are using or for the host system.
Take into account the following notes on EMC-compatible installation of the
ET 200L distributed I/O device:
We recommend that you place the cable shield of the PROFIBUS-DP on
both sides of a shield bus.
The chassis ground and the ground terminal are interconnected in the
ET 200L distributed I/O device. Connect the ground terminal of the
ET 200L distributed I/O device using a copper cable of at least 2.5 mm
to the central grounding point in the installation cabinet.
In the case of the ET 200L-SC, connect the ground terminals of the
ET 200L-SC and Smart Connect SC using a short copper cable of at least
2
2.5 mm .
ET 200L, ET 200L-SC and ET 200L-SC IM-SC Distributed I/O Device
Required for ...
Power supply PS 307 and Sie-
mens Series 6EP1 load current
25 VAC power supplies have this charac-
teristic
If the output tolerances are ex-
ceeded, we recommend that you
install a back-up capacitor. Rat-
ing: 200 F per 1 A load current
(with full-wave rectification).
-
compatible installation and wiring in the manual
Remarks
2
EWA 4NEB 780 6009-02c