ABB REL 352, Инструкция по эксплуатации

Страница: 26 / 163

Power Automation and Protection Division I.L. 40-201.9
REL 352 Version 1.00 3-5
3
7.2. Single Phase-to-Ground
Single phase-to-ground fault detection (see Figure 3-10) is accomplished by 3 non-directional
phase units (A, B, C). Expressions 1 and 2 (below) are for the operating and reference quantity,
respectively. The unit will produce output when the operating quantity leads the reference quan-
tity.
eq. (1)
and
eq. (2)
where
V
XG
= V
AG
, V
BG
or V
CG
I
X
= I
A
, I
B
or I
C
I
0
= zero sequence relay current
Z
1L
, Z
0L
= Positive and zero sequence line impedance in relay ohms
Z
FG
= Forward zone reach setting in secondary ohms for SLGF
Z
RG
= Reverse reach setting in secondary ohms for SLGF
7.3. Three-phase
Three-phase fault detection ( see Figure 3-11) is accomplished by the logic operation of one of
the three ground units, plus the 3øF output signal from the phase selector unit.
However, for a 3-phase fault condition, the computation of the distance units will be:
V
XG
- I
X
Z
P
eq. (3)
and
eq. (4)
where
V
XG
= V
AG
, V
BG
, V
CG
I
X
= I
A
, I
B
or I
C
Z
RG
= Phase reach setting in secondary ohms for SLGF.
7.4. Phase-to-Phase
The Phase-to-Phase unit ( see Figure 3-12) responds to all forward Phase-to-Phase faults, and
some phase-phase-to-ground faults. Expressions 5 and 6 are for operating and reference
V
XG
I
X
Z
0L
Z
1L
–
Z
1L
----------------------- I
0
+ Z
FG
–
j V
XG
I
X
Z
OL
Z
1L
–
Z
L
------------------------ I
0
+
 
 
Z
RG
+
j V
XG
I
X
Z
RG
+
[ ]