Distance Measurement - ABB RELION REB500 Technical Manual

Section 5
Bay protection functions
This is achieved by arranging for all the distance relays on the system to measure the same
ground fault loop and this is the purpose of the phase selection function.
The logic of the phase selection function provides a choice of the following sequences:
Table 50: Phase selection function
Starters
L1, L2, E
L2, L3, E
L3, L1, E
L1L3L2L1 cyclic (L1 before L3, L3 before L2, L2 before L1) means, for example, that for a cross-
country fault L3-L1-E, L1 phase (the L1-E loop) is measured rather than L3 phase, for a cross-
country fault L2-L3-E, L3 phase (the L3-E loop) rather than L2 phase and for a cross-country
fault L1-L2-E, L2 phase (the L2-E loop) rather than L1 phase.
L1L3L2 acyclic (L1 before L3 before L2) means, for example, that for a cross-country fault L3-L1-
E, L1 phase (the L1-E loop) is measured rather than L3 phase, for a cross-country fault L2-L3-E,
L3 phase (the L3-E loop) rather than L2 phase and for a cross-country fault L1-L2-E, L1 phase
(the L1-E loop) rather than L2 phase.
5.1.7.2

Distance measurement

Measurement procedure
The distance measurement of a fault is enabled after one of the two starting functions,
overcurrent or underimpedance, has picked up twice.
Initially the fault loop determined by the phase selection function is measured. This is called
processing period I and lasts until a trip signal is generated in the first zone or a maximum of
one period of the power system frequency.
At the latest after one period of the power system frequency, all six impedance loops are
measured. This is called processing period II, during which the three phase-to-ground loops
and the three phase-to-phase loops are measured alternately.
Comparison of the results of the six measurements eliminates those impedance loops, which
are not involved in the fault (selectivity conditions).
The timer started by the starting units controls the comparison of the measured impedances
with the polygon characteristic.
Measurement during processing period I
Processing period I lasts from the instant a starter picks up until the first tripping signal is
generated, but is restricted to a maximum of one period of the power system frequency. The
input signals are the phase currents I
of any parallel circuit I
line (3I
0m
and digitally filtered and broken down into their component vectors.
If the overcurrent starters are in operation and have picked up, the phase selection function is
performed and the loop to be measured determined. Should this not be the case, the loop
determined by the underimpedance starters is measured.
The impedance of a phase-to-ground loop, for example, L1-E is calculated using the equation:
58
Fault loop measure in relation to "PhaseSelMode"
L1L3L2L1 L3L1L2L3
cycl. cycl.
L2E L1E
L3E L2E
L1E L3E
(3I ), the neutral current I
Em 0m
) and the three phase-to-ground voltages U
© Copyright 2019 ABB. All rights reserved
L1L3L2 L1L2L3 L3L2L1
acycl. acycl. acycl.
L1E L1E L2E
L3E L2E L3E
L1E L1E L3E
, I , I , the residual current IE (3I
L1 L2 L3
of any parallel circuit of a double-circuit
Em
, U and U
L1 L2
1MRK 505 406-UEN B
L3L1L2 L2L1L3 L2L3L1
acycl. acycl. acycl.
L1E L2E L2E
L3E L2E L2E
L3E L1E L3E
GUID-4758E276-EF78-407E-A4FB-4DBDB27D8DF6 v1
GUID-E268B4D1-355B-4054-93C6-A238ED29EDCA v1
), the residual current
0
. All are sampled, analogue
L3
Bay protection functions REB500
Technical manual