Preparing The Switchgear Room - Siemens 8DJH Installation And Operating Instructions Manual

7.7 Preparing the switchgear room

500-8384.9 • Version 11 • Installation and Operating Instructions • 8DJH
In an environment with heavy electromagnetic interference it may be necessary to use shielded
cables and wires for the external connections. This makes it possible to avoid interferences in the
low-voltage compartment and thus, undesired influences on the electronic protection and
control or other automation devices.
Cable shields must be electrically bonded to be able to carry high frequencies, and contacted
concentrically at the cable ends.
The shields of cables and wires are connected and earthed in the low-voltage compartment.
Connect the shields to earth potential - with high electrical conductivity and all around as far as
possible. Protect the contact surfaces from corrosion in case of humidity (regular condensation).
When laying cables into the switchgear assembly, separate the control, signaling and data cables
and other lines with different signal and voltage levels, e.g. by laying them on separate racks or
riser cable routes.
Corresponding to the different shield designs, there is a number of methods to perform
connection. The planning department or site management determines which of the methods
will be used, taking EMC requirements into account. The preceding points should always be
taken into account.
The shield is connected to cables or wires with clamps contacting all around. If low demands are
placed on EMC, it is also possible to connect the shield directly to earth potential (combine or
twist the shield wires) or via short cable connections. Use cable lugs or wire-end ferrules at the
connecting points.
Always keep the connecting leads of the shields as short as possible (<10 cm).
If shields are used as protective earth conductors at the same time, the connected plastic-
insulated lead must be marked green/yellow over its entire length. Non-insulated connections
are inadmissible.
Incorrectly dimensioned cable basements or floor openings
A too small cable basement or incorrect floor openings can damage the connection cables or
the switchgear and impair the internal arc classification (IAC).
☒ The cable basement must allow adequate space for connecting and laying the
connection cables.
☒ The pressure relief rooms must be according to the dimension drawing in the
switchgear documentation.
☒ The dimensions of the floor openings must be according to the dimension drawing in
the switchgear documentation.
⇨ Do not violate the minimum cable bending radius of the cables.
Possible switchgear installations
▪ Wall-standing arrangement
▪ Free-standing arrangement (option)
Switchgear dimensions
Switchgear dimensions [▶ Page 69, "Floor openings and fixing points"] or in den order
documentation (dimension drawing, front views).
Pressure relief
In the standard design, the pressure is relieved downwards [▶ Page 23, "Pressure relief"].
Weights
Specifications on weights [▶ Page 35, "Dimensions and weights"].
Door dimensions
The necessary door dimensions depend on the following specifications:
▪ Number of panels in a transport unit
▪ Design with or without low-voltage compartment
NOTICE
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