[richtl-ueberstrom-060724, 1, en_US]
Figure 2-29
Directional characteristic of the time overcurrent protection
Definite Time Overcurrent Element 67-1
The directional overcurrent elements basically work in the same way as the non-directional elements. Pickup,
however, depends on the result of the direction determination. The direction determination is accomplished
using the measured quantities and the corresponding directional characteristics.
67-B2 PICKUP is used as setting values for the phase current; 67N-B2 PICKUP is used for the ground
current. A trip command is issued after pickup of an element and expiration of the associated time delays 67-
B2 DELAY or 67N-B2 DELAY. The dropout value is approximately 7% below the pickup value, but at least
1.8% of the nominal current, below the pickup value.
Figure 2-30 shows the logic diagram of the 67-1 elements. They can be blocked via the binary input
>BLOCK
51N
. Additionally, the ground current element can be blocked separately via the binary input
>BLOCK 67N-
TOC
.
The binary input
>5X-B InstTRIP
and the evaluation of the indication “switch” (onto fault) can act sepa-
rately on the directional phase and/or ground element.
Parameter 67(N)-B2 Pil/BI (address 2628) determines whether a non-delayed trip of this element via
binary input
>5X-B InstTRIP
is possible (YES) or impossible (NO). This parameter is also used for instanta-
neous tripping before automatic reclosing.
The indications
67(N) forward
or
67(N) reverse
are created from the individual directional indications
(7257 to 7264) determined specifically for the phase or current if a valid direction was determined for a phase
or ground current (forward or reverse). These indications can then be transmitted to another device where
they can cause instantaneous tripping there if an overcurrent element of the receiving device has picked up,
too. The indications must be linked via CFC to this end.
Functions
2.4 Backup overcurrent
78 SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
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