Siemens 7SJ85 - Structure of the Function; Function Description

i
i
NOTE
For current-sum supervision, the ground current of the line to be protected must be connected to the 4th
current measurement input (I
N
).
Structure of the Function
The Current-sum supervision function is located in the Power-system data of each 3-phase current meas-
urement point.
[dwstrcss-300913, 2, en_US]
Figure 9-27 Structure/Embedding of the Function
Function Description
The current sum is generated by addition of the current phasors. Errors in the current circuits are detected if
IF = |IA + IB + IC + kl• IN| > Threshold + Slope factor •Σ | I |.
[lokensum-300311-01.tif, 1, en_US]
Figure 9-28 Characteristic of the Current-Sum Supervision
9.3.11.2
9.3.11.3
Supervision Functions
9.3 Supervision of the Secondary System
1276 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017