12-Pulse Mode (Only Possible With The Optional Rs485 Interface); General Information On 12-Pulse Mode, Application - Siemens SIMOVERT Master Drives 6SE70 Betriebsanleitung

Connection
3.8

12-pulse mode (only possible with the optional RS485 interface)

3.8.1

General information on 12-pulse mode, application

12-pole operation is possible only with equipment software version 3.0 and higher.
12-pulse mode is implemented to reduce the harmonic loading on the mains supply..
Two 6SE70 units (common rectifiers) are connected in parallel on the output side and supplied on the line side
with two 3-phase AC supplies, galvanically isolated and with a phase offset of 30 degrees. One unit, the "12-
pulse master", controls the DC link voltage and provides the setpoint current for the other unit, the "12-pulse
slave".
Note: A unit described here as a "slave" is a completely normal common rectifier with a CUR electronic module
and is only transformed into a "12-pulse slave" by the appropriate parameterization. The term "12-pulse slave"
must not be confused with a "parallel unit" for the connection of power sections in parallel because the latter
does not contain a CUR electronic module and has a different order No. (see Section 3.7).
The two 3-phase galvanically isolated AC supplies with a phase offset of 30 degrees are usually generated
using a transformer with 2 different secondary systems (e.g. Y y6 d5, i.e. primary winding: star, secondary
winding 1: star, secondary winding 2: delta). A transformer of this type will be referred to below as a "12-pulse
transformer".
To implement 12-pulse mode, the two common rectifiers must be coupled via a fast serial link. The SST2 serial
interface for the basic unit is used for this purpose which is however only available as an RS485 interface once
the optional A2 submodule (C98043-A1690) has been plugged into the A10 CUR electronic module (C98043-
A1680). See Sections 9.6 and 3.8.7).
The transmission protocol used for SST2 is the "Peer-to-Peer" protocol.
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ENGLISH Siemens AG 6SE7087-6AK85-0AA0
Common Rectifier Operating instructions
09.02