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2 CALCULATION OF SETTINGS
902: BYPASSTL3 - Bypass Line Pickup Time Delay
If simultaneous reclosing is used and if I1PICKUP (Protection Setting 903) must be set below full load, then set
BYPASSTL3 = NO, otherwise set BYPASSTL3 = YES.
903: I1PICKUP - I1 Pickup Setting
I1 is the overcurrent trip unit used in the Line Pickup function, and it operates on the magnitude of the posi-
tive-sequence current.
I1PICKUP should be set no greater than 2/3 of the minimum fault current for an internal three-phase fault at
the relay location. If the minimum fault current is greater than the maximum load current on the protected line,
then the I1 setting can be reduced to provide greater coverage of the line. For this case, a setting of 110% of
the maximum load current is proposed.
The Remote-Open Detector (ROD) function issues a trip signal when the remote breaker opens during an
unbalanced internal fault. This function detects that the remote breaker has opened by recognizing charging
current on one or more phases following opening of the remote breaker. The Remote-Open Detector will not
operate for a balanced three phase fault.
ROD can speed up tripping at the end of the line that otherwise would be the slowest to respond in a sequen-
tial-tripping condition. In a Step Distance scheme, ROD tripping is beneficial for any unbalanced internal fault
not detected by Zone 1. In a Blocking scheme, ROD tripping is beneficial where system conditions are such
that the fault current redistribution following breaker opening at one end is normally required before the other
end(s) operates. The ROD function is not considered as a replacement or substitute for a pilot scheme.
Figure 2–12: ROD LOGIC DIAGRAM is a functional logic diagram of the ROD function. The sequence of
events that results in an ROD output is as follows:
IA LEADS
VA BY 90°
IB LEADS
VB BY 90°
IC LEADS
VC BY 90°
1. No charging current is detected prior to the fault – logic 0 output from AND2.
2. A fault is detected – logic 1 output from OR3.
3. The remote breaker opens and charging current is detected – logic 1 output from AND3.
4. The fault is still present, so the two inputs to AND4 persist and a trip output will be produced following the
time-delay setting of timer TL20.
GE Power Management
1
1
F A U L T
D E T E C T O R
3
A N Y Z O N E 2
P H A S E - D I S T A N C E
3
F U N C T I O N
A N Y Z O N E 2
G R O U N D - D I S T A N C E
F U N C T I O N
Figure 2–12: ROD LOGIC DIAGRAM
LPS-D Line Protection System
2.3 PROTECTION SETTINGS
2.3.11 REMOTEOPEN
2
2
T L 2 0
A
4
TRIP
0
A = 10 - 100
R e m o t e O p e n . v s d
2
2-
33
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