Connections And Interference Suppression; Equipotential Bonding - Siemens SINAMICS G120D Getting Started

Installation

3.11 Connections and interference suppression

3.11 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, 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 currentoperated coils, and freewheeling diodes for DC current-operated
coils). The interference suppressors must be connected directly on each coil.
3.12

Equipotential bonding

Grounding and high-frequency equipotential bonding measures
Equipotential bonding within the drive system has to be established by connecting all
electrical and mechanical drive components (transformer, motor and driven machine) 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:
1. Use a shielded motor cable.
2. Connect the cable shield both to the motor connector on the inverter and to the motor
terminal box.
3. 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.
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SINAMICS G120D converter with control units CU240D-2 and CU250D-2
Getting Started, 04/12014, FW V4.7, A5E34262374B AA