ABB REL650 Applications Manual page 55

1MRK 506 334-UUS A
Application manual
V / 3
-
ph ph
=
I
+
Z Z
1 ,Line 1 ,Source
GUID-3662A0FC-7F22-4848-B102-B12D1E0E79F2-ANSI V1 EN
where:
Z 0+j10 ohms
1Source
This gives the following arc resistance:
28700
» × =
R 5 2.0
arc
1.4
2900
GUID-7F53DA3B-DBDA-48B3-BB90-086549386590 V1 EN
This is the minimum value for the fault resistance reach RFPP1 setting. It can be
valuable to have much higher RFPP1 setting. RFPP1 = Z1 setting is proposed.
6. If CharPGZ1 is selected as Quadrilateral then set RFPG1 to 30.00 Ω.
For phase-to-ground faults the fault current flows to ground via ground wires and the
tower foots. The resistance is thus depending on the ground resistivity (tower footing
resistance) and the resistance of grounded shield wires, if existing.
The fault resistance can be written:
R ≈ R + R
arc towerfoot
The fault current for a single phase-to-ground fault at the open line end and
minimum short circuit capacity is:
×
3
=
3 I
(
0
× +
2 Z Z
1 ,Line 1 ,Source
= Ð - °
2 3 . 80 1 . kA
GUID-9C28B81C-7A4F-4F1C-BD8A-1F08C2EBAD6F-ANSI V1 EN
where:
Z 2.5+j17.5 ohms
1line
Z 12.5+j37.5 ohms
0line
Z 0+j10 ohms
1source
Z 0+j8 ohms
0source
This gives the following arc resistance (arc length: 2m):
28700
» × =
R 2 1.1
arc
1.4
2300
GUID-4A646317-F5F1-4B6C-8B34-A3FB94D368E3 V1 EN
138 / 3
= = Ð -
2 9 . 84 8
+ +
2 5 . j . 17 5 j 10
W
V / 3
-
ph ph
=
)
+ +
2 2 5
Z Z
0 ,Line 0 ,Source
W
REL650 setting examples
°
. kA
×
3 138 / 3
( ) (
× + + + +
. j . 17 5 j 10 12 5 .
Section 3
(Equation 7)
(Equation 8)
=
)
+
j 37 5 . j 8
(Equation 9)
(Equation 10)
49