ABB REL670 2.2 IEC, Applications Manual

Page: 295 / 908

Z
load
U
min
3 I
max
×
----------------------
=
EQUATION574 V1 EN-US
(Equation 224)
Z
loadmin
U
2
S
------- =
EQUATION571 V1 EN-US
(Equation 225)
Where:
U
is the minimum phase-to-phase voltage in kV
S is the maximum apparent power in MVA.
The load angle ArgLd can be derived according to equation 226 :
max
cos
max
P
ArgLd a
S
=
æ ö
ç ÷
è ø
EQUATION1623 V1 EN-US
(Equation 226)
where:
Pmax
is the maximal active power transfer during emergency conditions and
Smax is the maximal apparent power transfer during emergency conditions.
The RLd can be calculated according to equation 227 :
cos( ) RLd ZLoad ArgLd
= ×
EQUATION1624 V1 EN-US
(Equation 227)
The setting of RLd and ArgLd is by default set to 80 ohm/phase and 20 degrees.
Those values must be adapted to the specific application.
8.9 Distance protection zone, quadrilateral
characteristic, separate settings ZMRPDIS,
ZMRAPDIS and ZDRDIR
GUID-7308DB86-32CE-4615-95DC-92BEEF69E184 v1
1MRK 506 369-UEN B
Section 8
Impedance protection
Line distance protection REL670 2.2 IEC 289
Application manual