X X
I
I
X X
DA A
F
A
C1 1
1
11
= + ⋅ −
( )
EQUATION1916 V2 EN (Equation 373)
X X
I
I
X X
DA A
F
A
C2 2
2
11
= + ⋅ −
( )
EQUATION1917 V2 EN (Equation 374)
X X
I
I
X X
DA A
F
A
C3 3
3
11
= + ⋅ −
( )
EQUATION1918 V2 EN (Equation 375)
en06000621_ansi.vsd
BA1
A2
A3
D
B
D
A3
D
A2
D
A1
jX
11
I
A1
I
A2
I
A3
I
F
-jX
C
jX
1
jX
2
jX
3
F
X
ANSI06000621 V1 EN
Figure 214: Distance IED on adjacent
power lines are influenced by
the negative impedance
Normally the first zone of this protection must be delayed until the gap flashing has taken
place. If the delay is not acceptable, some directional comparison must also be added to
the protection of all adjacent power lines. As stated above, a good protection system must
be able to operate correctly both before and after gap flashing occurs. Distance protection
can be used, but careful studies must be made for each individual case. The rationale
described applies to both conventional spark gap and MOV protected capacitors.
Special attention should be paid to selection of distance protection on shorter adjacent
power lines in cases of series capacitors located at the line end. In such case the reactance
of a short adjacent line may be lower than the capacitor reactance and voltage inversion
phenomenon may occur also on remote end of adjacent lines. Distance protection of such
line must have built-in functionality which applies normally to protection of series
compensated lines.
Section 8 1MRK 506 369-UUS -
Impedance protection
416 Line distance protection REL670 2.2 ANSI
Application manual
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