1 1
3
138 3
2 9 84 8
2 5 17 5 10
ph ph
,Line ,Source
V /
/
I . . kA
Z Z . j . j
-
= = = Ð - °
+ + +
GUID-3662A0FC-7F22-4848-B102-B12D1E0E79F2-ANSI V1 EN (Equation 7)
where:
Z
1Source
0+j10 ohms
This gives the following arc resistance:
1.4
28700
5 2.0
2900
arc
R » × = W
GUID-7F53DA3B-DBDA-48B3-BB90-086549386590 V1 EN (Equation 8)
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
arc
+ R
towerfoot
The fault current for a single phase-to-ground fault at the open line end and
minimum short circuit capacity is:
( )
( ) ( )
0
1 1 0 0
3 3
3 138 3
3
2 2 5 17 5 10 12 5 37 5 8
2
2 3 80 1
ph ph
,Line ,Source ,Line ,Source
V /
/
I
. j . j . j . j
Z Z Z Z
. . kA
-
×
×
= = =
× + + + + +
× + + +
= Ð - °
GUID-9C28B81C-7A4F-4F1C-BD8A-1F08C2EBAD6F-ANSI V1 EN (Equation 9)
where:
Z
1line
2.5+j17.5 ohms
Z
0line
12.5+j37.5 ohms
Z
1source
0+j10 ohms
Z
0source
0+j8 ohms
This gives the following arc resistance (arc length: 2m):
1.4
28700
2 1.1
2300
arc
R » × = W
GUID-4A646317-F5F1-4B6C-8B34-A3FB94D368E3 V1 EN (Equation 10)
1MRK 506 334-UUS A Section 3
REL650 setting examples
49
Application manual
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