Failures; Interference Immunity By Screening; Cable Screens; Screen Connection - Eaton CEAG ZB-S Mounting And Operating Instructions

9 Failures

As a basic rule:
Stop device with the main switch when failures occur
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which can cause damage to persons, to property and/or
to operational safety.
Additionally disconnect device from power supply and
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protect against resetting.
After troubleshooting power up the system as
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described in chapter 7 .8.

9.1 Interference immunity by screening

Interference (e. g. radio interferences) can occur especially
in today´s highly automated industries. It can lead to
malfunctions and even to the failure of entire plants. The
overlaying of different types of interference increases the
overall level of radiated failure, hence the need to protect
all devices from electromagnetic interference (EMI). In
industrial process engineering in particular, a high level
of immunity is required for electrical instrumentation
and control (I & C) equipment. This is why all electronic
devices are subject to mandatory CE marking.
CEAG products comply with the requirements of EC
Directives 2004/108/EG (EMC directive), 2006/95/EG (low
voltage directive) and are entitled to carry the CE marking.
If luminaires with electronic ballast comply with the EMC
directives, then the interference produced by the high
frequency operation of the electronic ballast is within the
legal limits. Nevertheless, electronic devices may cause
interference in individual cases. As a rule only HF paging
systems (in the MHz range) should be used. Reliable
operation cannot be guaranteed with the use of inductive
paging systems (25-40kHz).
There are a number of ways in which interference can be
controlled.
Circuits should be separated from one another where
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possible and common returns (GND, Ground) kept as
short as possible.
Parallel cable runs should be kept as short as possible
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or avoided altogether.
The use of twisted cables can reduce inductive
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interference by a factor of 20.
The most important and most common method for
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suppressing interference is screening.

9.1.1 Cable screens

Cable screens usually consist of non-magnetic materials
such as copper or aluminium. The most popular screens
for cables and wires are individual braided screens
consisting of two interwoven sets of wires running in
opposite directions.
The density and thickness of the braid is the quality
characteristic of the screen. It is essential for the screen
to cover as much as possible of the area of the conductor
and so minimize the reciprocal of amplification. Cover
should be around 95% to achieve a good screen. At 60%
and below there is no guarantee of reliable immunity.
Mounting and Operating Instructions CEAG Central Battery System ZB-S 40071860179 (L) November 2018 www.ceag.de
Screen quick connectors SSA 5-10 for communication
lines with a cross section dimension of 5 to 10mm.
Order no. 400 71 347 133

9.1.2 Screen connection

The type of screen connection depends mainly on the
anticipated interference. Grounding the screen at one end
(1) is necessary to suppress electrical fields. Interference
caused by a magnetic alternating field on the other hand
can only be suppressed when the screen is connected at
both ends (2).
The avoidance of ground loops contributes to the trouble-
free operation of a system.
Condenser 220nF Y3
Ground loops with their familiar disadvantages must be
avoided when connecting a screen at both ends. High
voltage can be induced in large loops and this in turn
causes failures. The right way to avoid ground loops is to
make a starshaped ground or to take a Y3-condenser.

9.1.3 The fail-safe system

Companies therefore protect their plants from induced
EMI by screening their cables. Now the cable screen only
has to be connected inside the control cabinet to make
the connection to ground. This connection should be low-
impedance and with a low inductive resistance. Socalled
screen quick connectors (SSA 5-10) should be used for this.
The screen quick connector SSA 5-10 gets grounded by
potential connecting lines.
It is of course rare for just one cable to be routed into a
control cabinet. In most cases a number of data transfer,
supply and circuit cables have to be laid into the cabinet.
However every opening in the cabinet that can be avoided
is an avoidable cause of interference.
9 Failures
NOTE:
NOTE:
≥
4 KV
95