Settings - Siemens 7SC80 Manual

[einstellwert-tau-05s-260602-kn, 1, en_US]
It is important to note, however, that the longer the effective duration, the less accurate the result.
Example: Cable and current transformer with the following data:
Permissible continuous current
Maximum current for 1 s
v
Thus results:
[formel-k-0833-260602-kn, 1, en_US]
[formel-tau-3375-260602-kn, 1, en_US]
The settings are 49 K-FACTOR = 0,83; TIME CONSTANT = 33,75 min
Current limitation
In order to ensure that overload protection, on occurrence of high fault currents (and with small time
constants), does not result in extremely short tripping times thereby perhaps affecting time grading of the
short circuit protection, the thermal replica is frozen (kept constant) as soon as the current exceeds the setting
value 1107 I MOTOR START.
Warning Elements
By setting the thermal warning element 49 Θ ALARM (address 4204), a warning message can be issued
before reaching the tripping temperature. Tripping can thus be avoided by initiating early load reduction
measures. This warning element simultaneously represents the dropout level for the trip signal. Only when
this threshold is undershot, tthe tripping command will be reset and the protected equipment can be switched
on again.
The thermal element level is given in % of the tripping overtemperature.
A current warning level is also available (parameter 4205 I ALARM). The setting is set as the secondary
current in A (mperes) and should be equal to or slightly less than the permissible current k · Ι
used instead of the thermal warning element by setting the thermal warning element to 100 % thus virtually
disabling it.
Dropout time after emergency start
This function is not required for the protection of lines and cables. Since it is activated by a binary input indica-
tion, the parameter T EMERGENCY (address 4208) is not in effect. The factory setting can be retained.

Settings

2.11.3
Addresses which have an appended "A" can only be changed with DIGSI, under "Additional Settings".
The table indicates region-specific presettings. Column C (configuration) indicates the corresponding secon-
dary nominal current of the current transformer.
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017
2.11 Thermal Overload Protection 49
= 500 A at Θ = 40 °C
Ι
max u
= 45 · Ι = 22.5 kA
Ι
1s max
600 A/1 A
Functions
. It can be
Nom sec
223