Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546
(OP) 5-29
OP
DDB CB 1 Open C ph (906)
DDB CB 1 Open B ph (905)
INTSIG Phase A Undercurrent Operation
t
0
20ms
&
1
t
0
20ms
&
1
t
0
20ms
&
1
INTSIG Phase A Undervoltage Operation
DDB CB 1 Open A ph (904)
INTSIG Phase B Undercurrent Operation
INTSIG Phase C Undercurrent Operation
DDB CB Open 3 ph (903)
&
1
DDB Pole Dead C (894)
DDB Any Pole Dead (891)
DDB All Poles Dead (890)
DDB Pole Dead B (893)
DDB Pole Dead A (892)
INTSIG VTS Slow Block
P1112ENc
INTSIG Phase B Undervoltage Operation
INTSIG Phase C Undervoltage Operation
DDB CB2 Open A ph (912)
DDB CB2 Open B ph (913)
DDB CB2 Open C ph (914)
DDB CB2 Open 3 ph (911)
&
&
&
&
&
&
&
&
Figure 14 Pole dead logic for P544/P546
1.5.4 Residual compensation for earth/ground faults
For
earth faults, residual current (derived as the vector sum of phase current inputs (Ia + Ib +
Ic) is assumed to flow in the residual path of the earth loop circuit. Therefore the earth loop
reach of any zone must generally be extended by a multiplication factor of (1 + kZN)
compared to the positive sequence reach for the corresponding phase fault element.
Caution: The kZN Angle is different than previous LFZP, SHNB, and LFZR relays:
When importing settings from these older products, subtract angle Z1.
1.5.5 Mutual compensation for parallel lines
Whe
n applied to parallel circuits mutual flux coupling can alter the impedance seen by the
fault locator, and distance zones. The effect on the ground distance elements and on the
fault locator of the zero sequence mutual coupling can be eliminated by using the mutual
compensation feature provided. This requires that the residual current on the parallel line is
measured, as shown in the connection diagram. It is extremely important that the polarity of
connection for the mutual CT input is correct.
The major disadvantage of standard mutual compensation is that faults on a parallel line can
cause misoperation of the healthy line protection. The P54x uses fast dynamic control of the
mutual compensation, which prevents such misoperations of the healthy line protection,
while providing correct mutual compensation for faults inside the protected section. The
dynamic control is achieved by effectively eliminating the mutual compensation above a set
level of parallel line residual current (I MUTUAL) compared to the protected line residual
current (IN).
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