Siemens SINAMICS G130 Engineering Manual page 234

EMC Installation Guideline
Engineering Information
Effective shield bonding is achieved if EMC cable glands are used to create a solid 360° contact between the shield
and motor terminal box and, at the other side in the converter cabinet, a solid 360° contact with the EMC shield
busbar using EMC shield clips. An alternative shield connection to the PE busbar in the converter using only long,
braided "pigtails" is less suitable, particularly if the pigtails are very long, as this type of shield bond represents a
relatively high impedance for high-frequency currents.
Further additional shield bonds between the converter and motor, e.g. in intermediate terminal boxes, must never be
created as the shield will then become far less effective in preventing interference currents from spreading beyond
the drive system.
Motor terminal box
Shield bonding to the motor terminal box
using an EMC gland
Inside the cabinet units the housing of the Chassis units equipped with the standard, category C3 line filter must be
connected to the PE busbar and the EMC shield busbar with very low inductance. This connection can be
established with a large contact area by means of the metal components used in the construction of the cabinet units.
The contact surfaces must be bare metal and each contact point must have a minimum cross-section of several cm².
This connection can also be established by means of short ground conductors with a larger cross-section (≥ 95 mm²).
These must be designed to provide low impedance over a wide frequency range (e.g. made of finely stranded,
braided round copper wires or finely stranded, braided flat copper strips).
SINAMICS G150 / S150 cabinet units and S120 Cabinet Modules are designed in such a way that low-inductance
connections between the housing of the integrated Chassis units and the PE busbar and the EMC shield busbar is
ensured.
The rules to be followed for connecting Chassis units to the PE busbar and the EMC shield busbar are the same as
those for connecting optional category C2 line filters to the PE busbar and the EMC shield busbar. The optional
category C2 line filters must always be used in combination with line reactors for optimal filtering.
Measures for reducing high-frequency, radiated, electromagnetic interference emissions
In addition to the steep voltage edges at each switching of an IGBT in the inverter, other causes for high-frequency
electromagnetic interference are high-frequency, switched-mode power supplies and extremely high-frequency
clocked microprocessors in the control units of SINAMICS converters.
To limit this interference radiation, closed converter cabinets acting as Faraday cages are required in addition to
shielded motor and signal cables, for which optimal shield bonding must be established at both ends.
If SINAMICS G130 Chassis units and S120 Chassis units are integrated in an open cabinet frame, the interference
radiation of the devices is not limited to a sufficient degree. To ensure compliance with category C3 of EMC product
standard EN 61800-3, the room where the equipment is installed must have a suitable high-frequency shielding that
ensures adequate shielding (e.g. installing the open cabinet frames in a container with a metallic closure).
SINAMICS Engineering Manual – November 2015
234/528
Ó Siemens AG
EMC gland
Shield bonding to the EMC shield busbar in the converter
using an EMC shield clip