Functions
2.5 Distance Protection
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
119
2.5.1.2 Pickup (optional)
Prerequisite
If the distance protection in the 7SD5 is configured as the main or backup protection function, the distance pro-
tection features a range of pickup modes depending on the ordered version. It is possible to select the mode
that matches the respective network conditions. If, according to the ordering code, the device only has imped-
ance fault detection (7SD5***-*****-*E** and 7SD5***-*****-*H**), or if you have set Dis. PICKUP = Z<
(quadrilat.) (address 117) as pickup mode during the configuration, please go to Section 2.5.1.3 „Calcu-
lation of the Impedances“. For the ordering codes 7SD5***-*****-*D**, 7SD5***-*****-*G** and 7SD5***-*****-
*K**, apply the following Section.
Fault detection has to detect a faulty condition in the power system and initiate all necessary procedures for
selective clearance of the fault:
• Start of the delay times for the directional and non-directional final stages,
• Determination of the faulted loop(s),
• Enabling of impedance calculation and direction determination,
• Enabling of trip command,
• Initiation of supplementary functions
• Indication/output of the faulted conductor(s).
The pickup mode selected at address 117 Dis. PICKUP = Z< (quadrilat.) works implicitly, i.e the above-
mentioned operations are executed automatically as soon as a fault is detected in one of the distance zones.
Overcurrent Pickup
Overcurrent pickup is a phase-selective pickup procedure. After numeric filtering, the currents are monitored in
each phase if a settable value is exceeded. A signal is output for the phase(s) where the set threshold has been
exceeded.
For processing the measured values (see Section 2.5.1 „Calculation of the impedances“) the phase-selective
pickup signals are converted into loop information. This depends on the earth fault detection and - in earthed
power systems - on the parameter 1ph FAULTS according to table 2-4. For single-phase pickup without earth
fault detection in non-earthed power systems the phase-to-phase loop is always selected.
The phases that have picked up are signalled. If an earth fault has been detected, it will also be alarmed.
Pickup will drop if the signal falls below approx. 95 % of the pickup value.
Table 2-4 Loops and phase indications for single-phase overcurrent pickup
1)
only active for earthed power systems
Pickup
Module
Earth Fault
Detection
Parameter
1ph FAULTS
Valid Loop Alarmed
Phase(s)
L1
L2
L3
No
No
No
phase-to-
phase
L3-L1
L1-L2
L2-L3
L1, L3
L1, L2
L2, L3
L1
L2
L3
No
No
No
phase-to-earth
1)
L1-E
L2-E
L3-E
L1
L2
L3
L1
L2
L3
Yes
Yes
Yes
any
L1-E
L2-E
L3-E
L1, E
L2, E
L3, E
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