ABB Relion 670 series - Load Impedance Limitation, with Load Encroachment Function Activated; Setting of Minimum Operating Currents

min
2 1 0
0.8 cos sin
2 1 0
load
R R
RFPG Z
X X
× +
£ × × ¶ - × ¶
× +
é ù
ê ú
ë û
EQUATION1721 V2 EN (Equation 93)
Where:
ϑ is a maximum load-impedance angle, related to the minimum load impedance conditions.
To avoid load encroachment for the phase-to-phase measuring elements, the set resistive
reach of any distance protection zone must be less than 160% of the minimum load
impedance.
load
1.6 ZRFPPZx


EQUATION579 V3 EN (Equation 94)
Equation 94 is applicable only when the loop characteristic angle for the phase-to-phase
faults is more than three times as large as the maximum expected load-impedance angle.
More accurate calculations are necessary according to equation
95.
RFPP 1.6 Z
loadmin
cos J
R1PP
X1PP
---------------– sin J×× ×£
EQUATION580 V1 EN (Equation 95)
All this is applicable for all measuring zones when no power swing detection element is
in the protection scheme. Use an additional safety margin of approximately 20% in cases
when a power swing detection element is in the protection scheme, refer to the description
of Power swing detection (ZMRPSB, 68) function.
8.1.3.9 Load impedance limitation, with load encroachment function activated
The parameters for load encroachment shaping of the characteristic are found in the
description of the phase selection with load encroachment function, section
"Setting
guidelines". If the characteristic for the impedance measurement is shaped with the load
encroachment algorithm, the parameter RLdFw and the corresponding load angle ArgLd
must be set according to the minimum load impedance.
8.1.3.10 Setting of minimum operating currents
The operation of the distance function can be blocked if the magnitude of the currents is
below the set value of the parameter IMinPUPP and IMinPUPG.
Section 8 1MRK 506 369-UUS -
Impedance protection
214 Line distance protection REL670 2.2 ANSI
Application manual