User's Manual

Siemens PLT 130
.
1994
4/16
Overvoltage protection
Description
Fig. 4/23 Coarse overvoltage protection 6DS9 208-8AA
Application
The coarse and fine overvoltage protection components largely
protect the participants connected to the CS 275 bus from de-
struction as a result of overvoltages which result from interfer-
ences in the remote bus cable. The division into coarse and fine
protection means that it is possible to optimally match the over-
voltage protection to the respective system.
The coarse protection limits powerful, high-voltage pulses to the
arc voltage. It can briefly handle currents in the kA range.
The fine protection reduces the residual voltage between the
internal conductor and screen which passes the coarse protec-
tion to a measure which is non--hazardous for the amplifier of the
inductive coupler in the bus converter Ul.
The use of overvoltage protection components is not mandatory
for operation of the CS 275 remote bus in non-disturbed system
environments. But their use is recommended if the effect of
overvoltages onto remote bus cables cannot be excluded.
Important
notes:
The coarse and fine protection components do not replace a
lightning protection system installed according to the regula-
tions.
In conjunction with the so-called primary lightning protection
(connection and earthing of steel armoring, equipotential bond-
ing etc.) you can reduce the extent of damage to the bus partic-
ipants as a result of a lightning stroke, but this does not provide
complete protection from the damage of lightning.
Fig. 4/24 Fine overvoltage protection 6DS9 210-8AA
Design
Coarse pr
otection
The coarse overvoltage protection 6DS9 208-8AA is fitted in a
cast aluminum housing with degree of protection IP 54 and di-
mensions (l x w x h) 125 mm x 80 mm x 58 mm. It contains 2
lightning arresters.
It is connected via an M5 threaded bolt to the earthing system.
The screens of the remote bus cables which are combined in
the housing of the coarse protection can be connected if re-
quired to the earthing system either directly or via one of the two
lightning arresters (floating design).
The coarse protection is suitable for all types of remote bus
cables.
Fine pr
otection
The fine overvoltage protection basically consists of two Z
diodes and a terminator for the remote cable which can be con-
nected when needed via the connecting splicing plate on the
connector board AF instead of the resistor present there. These
components are located on a miniature PCB which can be fitted
in the connector board 6DS9 203-8CA or --8DA.
The coarse and fine protection components can also be retro-
fitted in existing system.
For configuring notes and ordering data see page 4/17.
Created with "Chameleon CMYK PDF Creator" for Wolfgang Strozyk at Siemens AG
This catalog is out of date, see note on page 2