Application and Setting Notes
Parameter: Threshold current warning
•
Default setting (_:101) Threshold current warning = 1.000 A at I
rated
= 1 A
Set the threshold to the maximum permissible continuous current (I
max, perm
). This results in the same setting
value as for the K-factor .
Parameter: Threshold thermal warn.
•
Default setting (_:104) Threshold thermal warn. = 90 %
The default setting can be left at a K-factor , of 1.1, as the thermal memory results for 83 % at continu-
ously flowing rated current. The calculation uses the rule of three: 100 % corresponds to ( K-factor )
2
and
x % corresponds to 1
2
.
[fowarnsc-100810-01.tif, 2, en_US]
At a K-factor of 1.05, the thermal memory for rated current is already 91 % filled. Increase the Threshold
thermal warn. to 95 %.
Parameter: Dropout threshold operate
•
Default setting (_:105) Dropout threshold operate = 90 %
The Dropout threshold operate parameter is used to drop out pickup and tripping when the value
drops below this threshold. A setting on the order of magnitude of the warning threshold is recommended.
You can select a lower setting value for special applications, desired additional cooling or longer blocking of
closing.
Note that the calculation of the operational measured value Time until close refers to this value.
Parameter: Emerg. start T overtravel
•
Default setting (_:112) Emerg. start T overtravel = 300 s
This functionality is not required for protection of lines and cables. If the logical binary indication is not routed,
the Emerg. start T overtravel will be ineffective. The Emerg. start T overtravel presetting
can therefore be retained.
Parameter: K-factor
•
Default setting (_:106) K-factor = 1.10
The K-factor parameter is used to describe the limiting value for the maximum permissible continuous load.
The rated current I
rated, obj
of the protected object (for example, cable) is the basic current for overload sensing.
You can determine the K-factor on the basis of the thermally permissible continuous current I
max, perm.
:
[fotolpkf-100810-01.tif, 2, en_US]
NOTE
The thermally permissible continuous current for the protected object is known from relevant tables or
from the specifications of the manufacturer!
7.26.5
Protection and Automation Functions
7.26 Thermal Overload Protection, 3-Phase - Advanced
886 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017
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