Line Pickup - GE LPS-D Instruction Manual

1.4 AUXILIARY PROTECTION FUNCTIONS
When a fault occurs, with an attendant drop in potential, the Any Phase Under Voltage signal picks up, but the
fault detector operates to prevent an output from AND1. PTFF does not operate on fault conditions.
1
a) THREE PHASE TRIPPING
The Line Pickup (Close-onto-Fault) logic provides tripping in the event that the breaker is closed into a zero-
voltage bolted fault, such as occurs if the grounding chains were left on the line following maintenance. For this
three phase zero voltage fault, the mho distance functions cannot operate because they lack a source of polar-
izing voltage. The figure below shows the functional logic for LPS-D Line Pickup.
O V E R R E A C H I N G P H A S E O R
G R O U N D D I S T A N C E
I 1 C U R R E N T
D E T E C T O R
A L L P H A S E S O P E N
A L L P H A S E V O L T A G E S
H I G H
P H A S E A
O P E N
P H A S E B
O P E N
P H A S E C
O P E N
( L P S - D W I T H S I N G L E P H A S E T R I P P I N G M O D E L S O N L Y )
When the line is de-energized, the open breaker is detected by the All phases Open input. The resulting output
causes timer TL401 to pickup 150 ms later. Consequently, when the line is energized and a fault current higher
than the setting of I1 exists, current detector I1 picks up and AND402 produces an output. If the Timer Bypass
setting is set to YES, AND403 immediately produces an output to initiate tripping of the breaker. If the Timer
Bypass setting is set to NO, then tripping occurs after the 45 ms pickup delay of timer TL403. Line Pickup is
primarily intended to trip for closing into zero-voltage bolted faults where the distance functions connected to
line-side potential will not operate. However, regardless of the I1 pickup setting, it can also be used to trip on
any type of permanent fault along the entire line length that produces voltage at the relay location that is suffi-
cient to operate a Zone 2 distance function, but not enough to pickup the All Phase Voltages High signal. This
is accomplished by routing Zone 2 phase-distance or ground-distance function outputs to AND401. The step
distance backup timers are bypassed by the Line Pickup logic.
If the line is energized and no fault exists, the all Phase Voltages High signal picks up and timer TL401 will
begin timing; 40 ms later the output of TL401 resets timer TL401 via the fast reset input. AND401 and AND402
have their lower input removed at that time to take the three phase Line Pickup out of service.
1-
14
M T
M T G
I1
T L 4 0 1
1 5 0
9 0
T L 4 0 2
4 0
0
F A S T
R E S E T
T L 4 0 4
1 5 0
9 0
4 0 4
M T G A
T L 4 0 5
1 5 0
9 0
4 0 5
M T G B
T L 4 0 6
1 5 0
9 0
4 0 6
M T G C
S I N G L E P H A S E T R I P P I N G C I R C U I T R Y
Figure 1–4: LINE PICKUP LOGIC DIAGRAM
LPS-D Line Protection System
4 0 1
T L 4 0 3
4 5
5
4 0 2
4 0 3
T I M E R
B Y P A S S
4 0 2
1 PRODUCT DESCRIPTION

1.4.2 LINE PICKUP

LINE PICKUP
4 0 1
T R I P
Input present on
Single Phase
Tripping Models only
GE Power Management