Siemens ET 200S - Page 547

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Distributed I/O System ET 200S
EWA 4NEB 780 6024-02 07
Determining the Leakage Resistance of an
ET 200S Station
Ohmic Resistance
When determining the leakage resistance for an ET 200S station (for a
ground-fault detector, for example), you must take into account the ohmic
resistance from the RC combination of each module:
Module Ohmic Resistance from RC Network
Interface module 10 MΩ (−5%)
PM-E 24 VDC power module 10 MΩ (−5%)
PM-E 24 VDC / 120/230 VAC power module –––
Formula
You can use the following formula to calculate the leakage resistance of an
ET 200S station if you secure all the modules listed above with a single
ground-fault detector:
R
ET 200S
+
R
Modul
N
R
Module
R
IM 151
R
PM-E 24 VDC
Leakage resistance of a module
Leakage resistance of the IM151-1 interface module
Leakage resistance of the PM-E 24 VDC power module
N
Number of power/interface modules in the ET 200S station
R
IM 151
+ R
PM*E DC24V
+ R
Modul
+ 9,5 M
R
ET 200S
Leakage resistance of the ET 200S station
Figure E-1 Formula for Determining the Leakage Resistance of an ET 200S Station
If you secure the modules listed above in an ET 200S station with a number of
ground-fault detectors, you must obtain the leakage resistance for each
ground-fault detector.
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