[lo_Stage Control, 1, en_US]
Figure 7-189 Logic Diagram of the Stage Control
RMS-Value Selection
The protection function supports 2 kinds of RMS measurement:
•
Normal RMS value
•
Gained RMS value from the function block Filter
The gained RMS value is automatically used if the function block Filter is configured and the filter has been
enabled.
NOTE
When the function block Filter is applied, only one current measuring point I-3ph is allowed to be
connected to the 3-phase current interface of the function group.
Thermal Replica
The protection function calculates the overtemperature from the phase currents based on a thermal single-
body model according to the thermal differential equation with
[fo_diffgl-170914, 2, en_US]
With the following standardization:
[fo_normie-170914, 3, en_US]
Θ Current overtemperature, in relation to the final temperature at a maximum permis-
sible phase current k I
rated, obj
Θ
Amb
Standardized ambient temperature, where ϑ
Amb
describes the coupled ambient temper-
ature. The coupled ambient temperature ϑ
Amb
can be the measured ambient tempera-
ture or the ambient temperature preset using the Default temperature param-
eter.
Δ ϑ
rated obj
Overtemperature of the protected object set at rated current
τ
th
Thermal time constant (temperature rise/cooling) of the protected object
Protection and Automation Functions
7.26 Thermal Overload Protection, 3-Phase - Advanced
882 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017
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