3 Mounting and Commissioning
238
7UM61 Manual
C53000-G1176-C127-3
Replacing Interfac-
es
The serial interfaces can only be exchanged in the versions for panel flush mounting
and cubicle mounting. Which interfaces can be exchanged, and how this is done, is
described in this Section under the margin title “Replacing Interface Modules”.
Terminating Resis-
tors for RS485 and
Profibus DP (Elec-
trical)
For reliable data transmission the RS 485 bus or the electrical Profibus DP must be
terminated in each case at the last device on the bus with resistors. The PCB of the
B–CPU processor module and the RS485 or Profibus interface module are equipped
for this purpose with terminating resistors that are switched in by means of jumpers.
Only one of the three options may be used for this. The physical location of the
jumpers on the PCB is described in this section under the margin title "Processor
Module B–CPU", and under the margin title "Bus-Capable Serial Interfaces" for the in-
terface modules. Both jumpers must be always plugged in identically.
The terminating resistors are disabled on unit delivery.
Spare Parts Spare parts can be the battery for storage of data in the battery-buffered RAM in case
of a power failure, and the internal power supply miniature fuse. Their spacial alloca-
tion is shown in Figures 3-3 and 3-4. The ratings of the fuse are printed on the board
next the fuse itself. When replacing the fuse, please observe the guidelines given in
the SIPROTEC
®
4 System Description /1/ in the chapter "Maintenance" and "Correc-
tive Action / Repairs".
3.1.2.2 Disassembly
Disassembly of the
Device
Note
It is assumed for the following steps that the device is not in operation.
To perform work on the boards, such as checking or altering switching elements or re-
placing modules, the buffer battery or the miniature fuse, proceed as follows:
Caution!
Caution when changing jumper settings that affect nominal values of the device
As a consequence, the order number (MLFB) and the ratings on the nameplate no
longer match the actual device properties.
If changes are necessary under exceptional circumstances, the changes should be
clearly and fully marked on the device. Self adhesive stickers are available that can be
used as supplementary nameplates.
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