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[lo_Stage Control, 1, en_US]
Figure 6-165
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
i
i
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
Θ
Amb
Δ ϑ
rated obj
τ
th
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
Logic Diagram of the Stage Control
Current overtemperature, in relation to the final temperature at a maximum permis-
sible phase current k I
Standardized ambient temperature, where ϑ
ature. The coupled ambient temperature ϑ
ture or the ambient temperature preset using the Default temperature param-
eter.
Overtemperature of the protected object set at rated current
Thermal time constant (temperature rise/cooling) of the protected object
6.19 Thermal Overload Protection, 3-Phase - Advanced
rated, obj
describes the coupled ambient temper-
Amb
can be the measured ambient tempera-
Amb
Protection and Automation Functions
655
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