Functions
2.3 Directional Overcurrent Protection 67, 67N
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
103
User-defined Characteristics
When user-defined characteristic are utilized, the tripping curve may be defined point by point. Up to 20 value
pairs (current, time) may be entered. The device then approximates the characteristic, using linear interpola-
tion.
The dropout curve may be user-defined as well. This is advantageous when the overcurrent protection must
be coordinated with conventional electromechanical overcurrent relays located towards the source. If no user-
defined dropout curve is required, the element drops out as soon as the measured signal is less than approx.
95% of the pickup setting. When a new pickup is evoked, the timer starts at zero again.
The following figure shows by way of an example the logic diagram for the 67-TOC relay element of the direc-
tional inverse time overcurrent protection of the phase currents.
Figure 2-25 Logic diagram for the directional overcurrent protection: 67-TOC relay element
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