Principle Of Operation - ABB Relion 670 Series Technical Reference Manual

1MRK505222-UUS C
6.15.2
Technical reference manual
based on the selected phase preference. A number of different phase preference
combinations are available for selection.

Principle of operation

Phase preference logic PPLPHIZ has 10 operation modes, which can be set by the
parameter OperMode. The different modes and their explanation are shown in
table 179 below. The difference between cyclic and acyclic operation can be explained
by the following example. Assume a A fault on one line and a C fault on another line.
For OperMode = 1231c the line with C fault will be tripped (C before A) while for
OperMode = 123a the line with A 1 fault will be tripped (A before C).
Table 179: Operation modes for Phase preference logic
OperMode Description
No filter No filter, phase-to-phase measuring loops are not blocked during single phase-to-
ground faults. Tripping is allowed without any particular phase preference at cross-
country faults
No pref No preference, trip is blocked during single phase-to-ground faults, trip is
allowed without any particular phase preference at cross-country fault
1231 c Cyclic 1231c; A before B before C before C
1321 c Cyclic 1321c; A before C before B before A
123 a Acyclic 123a; A before B beforeC
132 a Acyclic 132a;A before C beforeB
213 a Acyclic 213a; B before A before C
231 a Acyclic 231a; B before C beforeA
312 a Acyclic 312a; C before B beforeA
321 a Acyclic 321a; C before B before A
The function can be divided into two parts; one labeled voltage and current
discrimination and the second one labeled phase preference evaluation, see figure 198.
The aim with the voltage and current discrimination part is to discriminate faulty
phases and to determine if there is a cross-country fault. If cross-country fault is
detected, an internal signal "Detected cross-country fault" is created and sent to the
phase preference part to be used in the evaluation process for determining the condition
for trip.
The voltage and current discrimination part gives phase segregated pickup signals if
the respective measured phase voltage is below the setting parameter PU27PN at the
same time as the zero sequence voltage is above the setting parameter 3V0Pickup. If
there is a pickup in any phase the PICKUP output signal will be activated.
Section 6
Impedance protection
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