Connections And Interference Suppression; Equipotential Bonding - Siemens Sinamics CU240D-2 DP Operating Instructions Manual

● 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 or via electrically conductive
PG glands. These must connect the shields to the shield bonding options for cables and
the unit housing respectively with excellent electrical conductivity and a large contact
area.
● Use only metallic or metallized connector housings for shielded data cables (e. g.
PROFIBUS cables).
4.2.6

Connections and interference suppression

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 and the solenoid valves must have interference suppressors to
reduce high-frequency radiation when the contacts are opened (RC elements or varistors for
AC currentoperated coils, and freewheeling diodes for DC current-operated coils). The
interference suppressors must be connected directly on each coil.
No external suppression device is required for the motor holding brake.
4.2.7

Equipotential bonding

Grounding and high-frequency equipotential bonding measures
All electrical and mechanical drive components (transformer, motor and driven machine)
must be connected to the grounding system. 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 the motor must be interconnected with respect to the high-frequency point
of view:
● Use a shielded motor cable.
● Connect the cable shield both to the motor connector on the inverter and to the motor
terminal box.
● Use a short grounding connection from the PE terminal on the inverter to the metal frame.
The following figure illustrates all grounding and high-frequency equipotential bonding
measures using an example.
Converter with the control units CU240D-2
Operating Instructions, 04/2018, FW V4.9 SP10, A5E34262100B AF
Installation
4.2 Electrical Installation
43