SIEMENS
10/6
Siemens KT 10.1 · 2016
10
Add-on modules
Selectivity module
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Overview
Selectivity and rapid fault localization in 24 V feeders
The SITOP PSE200U and SITOP select selectivity modules are
the optimal expansion for all 24 V power supplies to distribute
the load current to several feeders and to monitor it. Overload
and short-circuit in one or more feeders is reliably detected and
signaled.
The electronics permit brief current peaks caused, for example,
by high inrush currents, but disconnects feeders in the event of
an extended overload. This is ensured even on high-resistance
lines and in the case of "creeping" short-circuits. In such cases,
miniature circuit breakers fail to trip, or trip too late, even if the
power supply unit could deliver the required tripping current.
The SITOP expansion module continues to supply the intact
feeders with 24 V absolutely free of interruptions and feedback
– a feature which avoids a possible total system failure.
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Benefits
•
Reliable shutdown in case of overload regardless of cable
lengths or cable cross-sections
•
4 load feeders per module with individually adjustable
response threshold for each output
•
Two versions for remote diagnostics: Group signaling contact
or single-channel signaling
•
Evaluation via free-of-charge SIMATIC S7 function blocks
(S7-1500/1200/300/400) for modules with single-channel
signaling (PSE200U)
•
LEDs for rapid on-site fault localization
•
Remote reset possible from a central location (PSE200U)
•
Simple commissioning thanks to manual switch on/off of
outputs (PSE200U)
•
Sequential connection of feeders to reduce total inrush current
•
Sealable transparent cover over adjusters for currents and
times protects against maladjustment (PSE200U)
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Application
The selectivity module is used in conjunction with 24 V power sup-
plies to distribute the load current over several feeders and to mon-
itor the individual currents. Faults in individual circuits caused by
overload or short-circuit are detected and selectively switched off
so that further load current paths remain unaffected by the fault.
This achieves fast fault diagnostics and minimizes downtimes.
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Design
The selectivity module is specially designed for the response of
switched-mode power supply units and the 24 V DC feeders to
be supplied. Individual setting of the current allows optimum
adaptation to the respective feeder.
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Function
Monitoring
The current per output is monitored by the selectivity modules;
if the set threshold of the output is exceeded, the output is
switched off according to a predefined time-current characteris-
tic curve. In addition, the supplying 24 V input voltage is con-
stantly being monitored. As soon as this voltage threatens to fail,
the path with a higher current than the set threshold is discon-
nected immediately. All other feeders continue to be supplied
without interruption.
Signaling
Signaling of the faulty feeder takes place by the LEDs on the
device as well as via group signaling contact or single-channel
signaling. The selectivity module with single-channel signaling
outputs the status of the 4 outputs cyclically by means of a serial
code which can be read in by a digital PLC input.
Free function blocks for SIMATIC S7-300/400/1200/1500 for
STEP 7 and TIA Portal as well as SIMOTION CPUs with
SIMOTION SCOUT are available for evaluation. This enables
simple integration into the S7 diagnostics and host control or
HMI systems.
More information, as well as the function blocks for download,
can be found at:
SIMATIC S7:
SIMOTION:
Connection and disconnection of the outputs
During device startup you can select between simultaneous
connection of all outputs as well as sequential connection or
load-dependent connection of the outputs (to reduce the peak
inrush currents).
Each output can be manually connected and disconnected on
the device (for example, for commissioning or service). Discon-
nected outputs can be connected by means of remote reset
(24 V input). Prerequisite is that the outputs were not discon-
nected manually on the device.
Power
supply unit
Selectivity
module
Actuators
Sensors
24 V DC
G_KT01_XX_00122
HMI
PLC
© Siemens AG 2016