Cables Outside The Converter Cabinet; Cable Shields; Equipotential Bonding In The Converter Cabinet, In The Drive System, And In The Plant - Siemens SINAMICS G130 Engineering Manual

2.4.4

Cables outside the converter cabinet

·
All power cables (line supply cables, DC link cables, cables between braking choppers (Braking Modules)
and associated braking resistors, as well as motor cables) must be routed seperately from signal and data
cables. The minimum distance should be approximately 25 cm.
·
The power cable between the converter and motor must be shielded to ensure compliance with categories
C2 and C3 as defined by EN 61800-3. For high output power ratings, the connection should be made, where
possible, using a three-phase cable with 3 symmetrically arranged conductors. Ideal for this purpose are
shielded cables with symmetrically arranged three-phase conductors L1, L2 and L3, and an integrated,
symmetrical 3-wire PE conductor.
·
The shielded power cable to the motor must be routed separately from the cables to the motor temperature
sensors (PTC/KTY/PT1000) and the cable to the speed encoder, since the latter two are treated as signal
cables.
·
Signal and data cables must be shielded to minimize coupled-in interference with respect to capacitive,
inductive, and radiative coupling.
·
Particularly sensitive signal cables, such as setpoint and actual value cables and, in particular, tachometer
generator, encoder, and resolver cables must be routed with optimum shield bonding at both ends and
without any interruptions of the shield.
2.4.5

Cable shields

·
Shielded cables should ideally have finely stranded, braided shields, e.g. cables of type PROTOFLEX EMV-
FC of type 2XSLCY-J supplied by Prysmian. Less finely braided shields such as the concentric conductor in
cables of type Protodur NCYWY are less effective. Foil shields have a much poorer shielding effect and are
therefore unsuitable.
·
Shields must be connected to the grounded housings at both ends with excellent electrical conductivity and
a large contact area. Only when this method is used coupled-in interference with respect to capacitive,
inductive, and radiative coupling can be minimized.
·
Bonding connections for the cable shields should be established, where ever possible, directly behind the
cable entry into the cabinet. For power cables the EMC shield busbars should be used. For signal and data
cables the shield bonding options provided in the Chassis units and cabinet units should be used.
·
Cable shields should not be interrupted, wherever possible, by intermediate terminals.
·
In the case of both, the power cables and the signal and data cables, the cable shields should be connected
by means of suitable EMC shield clips. These must connect the shields to either the EMC shield busbar or
the shield bonding options for signal cables with excellent electrical conductivity and a large contact area.
·
As plug connectors for shielded data cables (e.g. PROFIBUS cables) only metallic or metallized connector
housings should be used.
2.4.6

Equipotential bonding in the converter cabinet, in the drive system, and in the plant

·
Equipotential bonding within a converter cabinet element has to be established by means of a suitable
mounting plate (back plane), to which all metallic housings of the devices and additional components
integrated in the cabinet element (such as converter Chassis, line filter, Control Unit, Terminal Module,
Sensor Module, etc.) are connected. The mounting plate (back plane) has to be connected to the cabinet
frame and to the PE or EMC busbar of the cabinet element with excellent electrical conductivity and a large
contact area. In liquid-cooled systems, this also applies to all metal pipes and all metal components of the
re-cooling unit.
·
Equipotential bonding between several cabinet elements has to be established by means of a PE busbar
which, in the case of larger cabinet units or the S120 Cabinet Modules system, runs through all the cabinet
elements. In addition, the frames of the individual cabinet elements must be screwed together multiple times
with sufficient electrical conductivity by means of special contact washers. If extremely long rows of cabinets
are installed in two groups back to back, the two PE busbars of the cabinet groups must be connected to
each other wherever possible.
·
Equipotential bonding within the drive system or the installation is implemented by connecting the
enclosures of all electrical and mechanical drive components (transformer, converter cabinet, motor,
gearbox, driven machine and, in the case of liquid-cooled systems, piping and re-cooling unit) to the
grounding system (protective earth PE). These connections are established by means of standard heavy-
power PE cables, which do not need to have any special high-frequency properties. In addition to these
connections, the inverter (as the source of the high-frequency interference) and all other components in
each drive system (motor, gearbox, and driven machine) must be interconnected with respect to the high-
frequency point of view. For this purpose cables with good high-frequency properties must be used.
EMC Installation Guideline
Engineering Information
SINAMICS Engineering Manual – November 2015
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