Siemens SIMATIC ET 200S - Determining the Leakage Resistance of an ET 200 S Station; Ohmic resistance; Formula

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ET 200S Distributed I/O System
EWA-4NEB 780602402-12
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 one 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 IM1511 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 MΩ
R
ET 200S
Leakage resistance of the ET 200S station
Figure E-1 Formula for calculating 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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