AngleRCA
0 0
V k I e- + × ×
EQUATION1638-ANSI V2 EN (Equation 72)
The negative-sequence voltage polarization with negative-sequence current
compensation (-U2Comp) compares correspondingly I
2
with (see equation 73), and
similarly it must be ensured that |V
2
| >> |k · I
2
| for reverse faults.
AngleRCA
2 2
V k I e- + × ×
EQUATION1639-ANSI V2 EN (Equation 73)
6.5 Phase preference logic PPLPHIZ
6.5.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Phase preference logic PPLPHIZ - -
6.5.2 Application
Phase preference logic function PPLPHIZ is an auxiliary function to Five zone distance
protection, quadrilateral characteristic (ZQMPDIS, 21) and Phase selection with load
encroachment, quadrilateral characteristic function FDPSPDIS (21). The purpose is to
create the logic in resonance or high resistive grounded systems (normally sub-
transmission) to achieve the correct phase selective tripping during two simultaneous
single-phase ground-faults in different phases on different line sections.
Due to the resonance/high resistive grounding principle, the ground faults in the system
gives very low fault currents, typically below 25 A. At the same time, the occurring system
voltages on the healthy phases will increase to line voltage level as the neutral
displacement is equal to the phase voltage level at a fully developed ground fault. This
increase of the healthy phase voltage, together with slow tripping, gives a considerable
increase of the risk of a second fault in a healthy phase and the second fault can occur at
any location. When it occurs on another feeder, the fault is commonly called cross-country
fault.
Different practices for tripping is used by different utilities. The main use of this logic is
in systems where single phase-to-ground faults are not automatically cleared, only alarm
is given and the fault is left on until a suitable time to send people to track down and repair
Section 6 1MRK 506 334-UUS A
Impedance protection
152
Application manual
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