Siemens 4 F-DO DC24V/2A PROFIsafe - Connecting Loads for Fail-Safe Modules; E.1 Connecting Capacitive Loads

ET 200S Distributed I/O System - Fail-Safe Modules
Installation and Operating Manual, 08/2008, A5E00103686-07
205
Connecting Loads
E
E.1 Connecting capacitive loads
Connecting capacitive loads on PM-E F pm DC24V PROFIsafe, EM 4 F-DO DC24V/2A PROFIsafe
If the electronic outputs of the PM-E F pm DC24V PROFIsafe, of EM 4 F-DO DC24V/2A are
connected to low-power loads that have capacitance, this can lead to generation of a "short-
circuit" error message. Reason: The capacitance cannot be sufficiently discharged during the
programmed self-test readback time.
The figure below shows the typical curves of the parameterized readback times indicating
the relationship between load resistance and connectable load capacitance.
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Remedy:
1. Determine the load current and capacitance of the load.
2. Locate the operating point in the diagram above.
3. If the operating point is above the curve, you must increase the load current until the new
operating point is below the curve by connecting a resistor in parallel.