Converter Cabinet Structure; Cables Inside The Converter Cabinet - Siemens SINAMICS G130 Engineering Manual

EMC Installation Guideline
Engineering Information
signal cables isolating amplifiers should be used. Sufficient space for bonding the cable shields must be provided,
whereby the braided cable shield must be connected to the converter cabinet ground with excellent electrical
conductivity and with a large contact area. In this respect, note that the ground potential between the zones must be
more or less identical. Differences must be avoided to ensure that impermissible, high compensating currents are
kept away from the cable shields.
2.4.2

Converter cabinet structure

·
All metallic components of the converter cabinet (side panels, back walls, roof plates, and floor plates) must
be connected to the cabinet frame with excellent electrical conductivity, ideally with a large contact area or
by means of several point-like screwed connections (i.e. to create a Faraday cage).
·
In addition to its existing protective ground connection, the frame of the cabinet must be connected at
several points to the foundation ground (meshed network) by a low-inductance connection suitable for high-
frequency currents. A description of suitable means of making this connection can be found in section
"Bearing currents caused by steep voltage edges on the motor" in chapter "Fundamental Principles and
System Description".
·
The cabinet doors must be connected to the cabinet frame with excellent electrical conductivity by means of
short, finely stranded, braided grounding strips, which are ideally placed at the top, in the middle, and at the
bottom of the doors.
·
The PE busbar and EMC shield busbar must be connected to the cabinet frame with excellent electrical
conductivity with a large contact area.
·
All metallic housings of devices and additional components integrated in the cabinet (such as converter
Chassis, line filter, Control Unit, Terminal Module, or Sensor Module) must be connected to the cabinet
frame with excellent electrical conductivity and with a large contact area. The best option here is to mount
devices and additional components on a bare metal mounting plate (back plane) with excellent electrical
conductivity. This mounting plate must be connected to the cabinet frame and, in particular, to the PE and
EMC shield busbars with excellent electrical conductivity and a large contact area. In liquid-cooled systems,
all metal pipes and all metal components of the re-cooling unit must be connected conductively to the
cabinet frame and the PE busbar.
·
All connections should be made so that they are permanent. Screwed connections on painted or anodized
metal components must be made either by means of special contact washers, which penetrate the isolating
surface and establish a metallically conductive contact, or by removing the isolating surface on the contact
points.
·
Contactor coils, relays, solenoid valves, and motor holding brakes must have interference suppressors to
reduce high-frequency radiation when the contacts are opened (RC elements or varistors for AC current-
operated coils, and freewheeling diodes for DC current-operated coils). The interference suppressors must
be connected directly on each coil.
2.4.3

Cables inside the converter cabinet

·
All power cables of the drive (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. Alternatively decoupling in the
converter cabinet can be implemented by means of separation plates connected to the mounting plate (back
plane) with excellent electrical conductivity.
·
Filtered line supply cables with a low level of interference (i.e. line supply cables running between the supply
system and the line filter) must be routed separately from non-filtered power cables with a high level of
interference (line supply cables between the line filter and the rectifier; DC link cables, cables between
braking choppers (Braking Modules) and associated braking resistors; as well as motor cables).
·
Signal and data cables, as well as filtered line supply cables, may only cross non-filtered power cables at
right angles of 90° to minimize coupled-in interference.
·
All cable lengths must be minimized (excessive cable lengths must be avoided).
·
All cables must be routed as closely as possible to grounded housing components, such as mounting plates
or the cabinet frame. This reduces interference radiation as well as coupled-in interference.
·
Signal and data cables, as well as their associated equipotential bonding cables, must always be routed in
parallel and with as short a distance as possible.
·
When unshielded single-wire cables are used within a zone, the feed and return lines must be either routed
in parallel with the minimum possible distance between them, or twisted with one another.
·
Spare wires for signal and data cables must be grounded at both ends to create an additional shielding
effect.
·
Signal and data cables should enter the cabinet only at one point (e.g. from below).
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