Directional Definite Time High-Current Elements 67-2, 67-3, 67N-2 And 67N-3 - Siemens 7SC80 Manual

Functions
2.3 Directional Overcurrent Protection 67, 67N
For line sections supplied from two sources or in ring-operated lines, the overcurrent protection has to be
supplemented by the directional criterion.
merged to one single source.
[zweiseitig-gespeister-leitungszug-260602-kn, 1, en_US]
Figure 2-24
Depending on the setting of parameter 613 Gnd O/Cprot. w., the ground current element can operate
either with measured values Ι
featuring a sensitive ground current input, however, use the calculated quantity 3Ι0.
The direction Forward, Reverse or Non-Directional can be set separately for each element.
For each element the time can be blocked via binary input or automatic reclosing (cycle-dependent), thus
suppressing the trip command. Removal of blocking during pickup will restart time delays. The Manual Close
signal is an exception. If a circuit breaker is manually closed onto a fault, it can be re-opened immediately. For
overcurrent elements or high-set elements the delay may be bypassed via a Manual Close pulse, thus resulting
in high-speed tripping.
Furthermore, immediate tripping may be initiated in conjunction with the automatic reclosing function (cycle
dependant).
Pickup stabilization for the 67/67N elements of the directional overcurrent protection can be accomplished by
means of settable dropout times. This protection comes into use in systems where intermittent faults occur.
Combined with electromechanical relays, it allows different dropout responses to be adjusted and a time
grading of digital and electromechanical relays to be implemented.
Pickup and delay settings may be quickly adjusted to system requirements via dynamic setting switching (see
Section 2.4 Dynamic Cold Load
Additionally using an inrush current detection, tripping by the directional elements in the phases and in the
ground path can be prevented when an inrush current is detected.

Directional Definite Time High-Current Elements 67-2, 67-3, 67N-2 and 67N-3

2.3.2
For each element, an individual pickup value 67-2 PICKUP, 67-3 PICKUP or 67N-2 PICKUP, 67N-3
PICKUP is set, which can be measured as Fundamental or True RMS. Each phase current and the ground
current is compared individually with the pickup value common for each element 67-2 PICKUP, 67-3
PICKUP or 67N-2 PICKUP, 67N-3 PICKUP. Currents above the setting values are signaled if the fault direc-
tion is equal to the configured direction. After the expiry of the associated time delays 67-2 DELAY, 67-3
DELAY, or 67N-2 DELAY, 67N-3 DELAY, the trip commands are issued, which are also available separately
for each element. The dropout value is roughly equal to 95 % of the pickup value for currents > 0.3 I
Pickup can be stabilized by setting the dropout times 1518 67 T DROP-OUT or 1618 67N T DROP-OUT. If
the current falls below the threshold, this time is started and maintains the pickup condition. Therefore, the
function does not drop out instantaneously. The trip command delay times 50-2 DELAY, 67-3 DELAY or
50N-2 DELAY, 67N-3 DELAY continue in the meantime. After the expiry of the dropout delay time, the
112
Figure 2-24
Transmission lines with sources at both ends
or with the values 3Ι0 calculated from the three phase currents. Devices
N
Pickup).
shows a ring system where both energy sources are
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017
.
nom