Replacement Of Converters In Simovert A 6Sc23 Range By Sinamics - Siemens SINAMICS G130 Engineering Manual

Replacement of converters in SIMOVERT A 6SC23 range by SINAMICS

Properties of the SIMOVERT A converter
SIMOVERT A converters are current-source DC link converters and therefore capable of 4Q operation without
modification or upgrading. Both the rectifier and the motor-side inverter are equipped with normal thyristors on 6SC23
devices.
Drive with SIMOVERT A 6SC23 current-source DC link converter
The voltage rate of rise at the inverter output is very significantly lower than on PWM converters with IGBTs. As a
result, the voltage stress on the motor winding and the bearing currents in the motor bearings are very low.
Since line and motor currents have a very high harmonic content on drives with current-source DC link converters,
high-power-output converters are usually operating as a 12-pulse configuration at both the line and the motor side. In
this instance, the motor-side inverter consists of a parallel connection which supplies a 12-pulse motor with two
separate windings mutually out of phase by 30 °el.
Properties of 1LA6 and 1LA1 motors operating on SIMOVERT A converters
•
The motors feature low-leakage rotor designs (special model for SIMOVERT A: With frame size 315L and
higher on 1LA6 motors and generally on 1LA1 motors).
•
1LA1 motors can be designed with a 6-pulse winding with a phase displacement of 0 °el., or a 12-pulse
winding with a phase displacement of 30 °el.
•
The insulation system on 1LA6 motors is comparable to the standard insulation on modern motors, while
the insulation system on 1LA1 motors is comparable to the special insulation on modern motors designed
for converter-fed operation at 690 V (see chapter "Motors").
•
1LA6 motors have no insulated bearing at the non-drive end. Due to their bigger frame size, 1LA1 motors
do have an insulated bearing at the non-drive end.
Replacement of SIMOVERT A converters by SINAMICS
It is not always possible to replace SIMOVERT A current-source DC link converters with voltage-source DC link
converters from the SINAMICS range. It is essential to analyze the existing drive constellation exactly for the
following reasons:
•
The special motor models for SIMOVERT A (frame size 315L and higher with 1LA6 series and 1LA1
series in general) are low-leakage, whereas PWM converters with a voltage-source DC link like
SINAMICS require high-leakage motors. The current spikes in the motor increase significantly in low-
leakage motors operating on SINAMICS converters. This carries the risk of tripping on over current in the
event of dynamic peak loads. For this reason, a SIMOVERT A converter used to supply motor models
specially designed for use with SIMOVERT A should be replaced by SINAMICS only for drive applications
without substantial load peaks. However, if the drive motors are basic models of 1LA6 up to frame size
315M, the issue of current spikes in the motor should not present a problem.
•
1LA1 motors can be of 6-pulse or 12-pulse design. With the 12-pulse design, the winding systems are
mutually out of phase by 30 °el.. This kind of 12-pulse motor can never be operated on a SINAMICS unit,
even when the converter is connected in parallel, because motors for SINAMICS cannot have out-of-
phase winding systems. For further details, please refer to the section "Parallel connections of
converters", in the chapter "Fundamental Principles and System Description".
General Engineering Information for SINAMICS
SINAMICS Engineering Manual - May 2008
Engineering Information
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