Grounding/Shielding; Connect To Earth Line And Leave Earthing Bridge Closed; Connect To Earth Line And Open Earthing Bridge; Connect To Own System Earth And Leave Earthing Bridge Closed - Honeywell MB-Secure 1000 Installation Instructions Manual

Installation Instructions MB-Secure 1000/2000/3000/4000/5000/6000
3.9

Grounding/Shielding

To protect against electromagnetic interference coupling such as occurs when electronic devices are switched
on and off, shielded cables must be installed and a suitable shielding circuit must be provided.
Care must be taken to connect the cable shields in the distributor sockets in such a way that they are not in
contact with other potentials. All shields in the control panel and in the main distributor should be joined by as
short a route as possible to one point.
(Earthing/shielding connector, see below)
The following variants are available for additional shield wiring:
3.9.1

Connect to earth line and leave earthing bridge closed

The brass rail (shield terminal block) at the cable inlet serve as a point of support to connect earth lines and
cable shields.
The earthing bridge (on PCBs) creates a capacitive coupling between the earth line and the reference potential
of the system operating voltage.
In general, this circuit offers the best protection against wireline faults and faults that occur due to cable shield
discharges. However, it should be adopted only if PE and N are installed separately (modern earthing) and the
earth line is guaranteed not to cause low or high-frequency signals.
3.9.2

Connect to earth line and open earthing bridge

The brass rail (shield terminal block) at the cable inlet serve as a point of support for connecting the earth line
and cable shields.
The capacitive coupling to the reference potential of the system operating voltage is broken by the open
earthing bridge (on PCBs). In some cases, this circuit is installed when the earth line is itself prone to faults, and
there is the danger of faults being transmitted to the system through capacitative coupling.
3.9.3

Connect to own system earth and leave earthing bridge closed

The brass rail (shield terminal block) at the cable inlet serve as a point of support for connecting the earth line
and cable shields. It should be connected to a new system earth that has to be set up.
For a very heavily loaded earth line, this is the only option to prevent interference on the cable shields.
Note: VDE 0800 Part 2 July 1980 Edition
VDE 0800 Part 2 AI Draft November 1982
23