ABB RELION 670 Series Applications Manual page 392

Section 7
Impedance protection
ArgLd : Angle in degrees of load encroachment characteristics
RLd : Positive sequence resistance in per unit
The procedure of calculating the settings for load encroachment consists basically of defining
load angle
zone 2 and zone 3 elements. For zone 2, the load encroachment can be enabled or disabled
using the
encroachment can be enabled or disabled using the
On or Off .
either
The load angle
calculation of the parameter setting. The parameter is set to the maximum possible load angle
at the maximum active load. A value larger than 20° must be used.
The blinder
æ
=
RLd ç
è
GUID-AF9BD6F2-E64B-424D-B361-49448A1CF690 V2 EN-US
Where,
Pexpmax
Umin
0.8
ArgLd
ArgLd
IEC11000304 V1 EN-US
Figure 238: Characteristics of load encroachment in R-X plane
386
ArgLd and resistive blinder RLd . The load encroachment logic can be enabled for
LoadEnchModZ2 setting by selecting either On or Off . Similarly for zone 3 load
ArgLd is same in forward and reverse direction, so it is suitable to begin the
RLd can be calculated according to the equation
ö
U
× ×
0.8 U min ÷
min
P ø
exp max
is the maximum exporting active power
is the minimum voltage for which
is the security factor to ensure that the setting of
resistive load
Load encroachment characteristic
jX
-RLd
LoadEnchModZ3 setting by selecting
Pexpmax occurs
RLd can be lesser than the calculated minimal
ArgLd
R
RLd
ArgLd
IEC11000304_1_en
1MRK 504 152-UEN B
425
(Equation 425)
Application manual