Basic Information about the Drive System
Monitoring and protective functions
7-263
E Siemens AG, 2004. All rights reserved
SINAMICS S120 Installation and Start-Up Manual, 12/04 Edition
7.9.2 Thermal monitoring and overload responses
Description
The priority of thermal monitoring for power components is to identify critical situa-
tions.
If alarm thresholds are exceeded, the user can set parameterizable response op-
tions that enable continued operation (e.g. with reduced power) and prevent imme-
diate shutdown. The parameterization options, however, only enable intervention
below the shutdown thresholds, which cannot be changed.
The following thermal monitoring options are available:
S I
2
t monitoring – A07805 – F30005
I
2
t monitoring is used to protect components that have a high thermal time
constant compared with semi-conductors. Overload with regard to I
2
t is present
when the converter load (r0036) is greater than 100% (load in % in relation to
rated operation).
S Heat-sink temperature – A05000 – F30004
Monitoring of the heat-sink temperature (r0037) of the power semi-conductor
(IGBT).
S Chip temperature – A05001 – F30025
Significant temperature differences can occur between the IGBT barrier junction
and the heat sink. These differences are taken into account and monitored by
the chip temperature (r0037).
If an overload occurs with respect to any of these three monitoring functions, an
alarm is first output.
The alarm thresholds p0294 (I
2
t monitoring) or p0292 (heat-sink or chip tempera-
ture monitoring) can be parameterized relatively to the shutdown values.
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