GE Multilin C60 UR series, Instruction Manual

Page: 312 / 544

5-184 C60 Breaker Protection System GE Multilin
5.7 CONTROL ELEMENTS 5 SETTINGS
5
Figure 5–90: BREAKER RESTRIKE SCHEME LOGIC
e) VT FUSE FAILURE
PATH: SETTINGS
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CONTROL ELEMENTS
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MONITORING ELEMENTS
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VT FUSE FAILURE 1(4)
Every signal source includes a fuse failure scheme.
The VT fuse failure detector can be used to raise an alarm and/or block elements that may operate incorrectly for a full or
partial loss of AC potential caused by one or more blown fuses. Some elements that might be blocked (via the
BLOCK
input)
are distance, voltage restrained overcurrent, and directional current.
There are two classes of fuse failure that may occur:
• Class A: loss of one or two phases.
• Class B: loss of all three phases.
Different means of detection are required for each class. An indication of Class A failures is a significant level of negative
sequence voltage, whereas an indication of class B failures is when positive sequence current is present and there is an
insignificant amount of positive sequence voltage. These noted indications of fuse failure could also be present when faults
are present on the system, so a means of detecting faults and inhibiting fuse failure declarations during these events is pro-
vided. Once the fuse failure condition is declared, it will be sealed-in until the cause that generated it disappears.
An additional condition is introduced to inhibit a fuse failure declaration when the monitored circuit is de-energized; positive
sequence voltage and current are both below threshold levels.
The function setting enables and disables the fuse failure feature for each source.
„
VT FUSE FAILURE 1
„
VT FUSE FAILURE 1
FUNCTION: Disabled
Range: Disabled, Enabled
RUN
Current interruption
detection logic
< 0.05 pu
for > ¼ cycle
I
t
mag
ARMED
RESET
SETTING
= Enabled
BREAKER RESTRIKE 1
FUNCTION
SETTING
= Off
BKR RSTR 1 BLK
AND
SETTING
= IA
BREAKER RESTRIKE 1
SOURCE
= IB
= IC
SETTING
= Off
BKR RSTR 1 BKR OPEN
SETTING
= Off
BKR RSTR 1 OPEN CMD
SETTING
= Off
BKR RSTR 1 CLS CMD
AND
OR
SETTING
BREAKER RESTRIKE 1 PICKUP
RUN
Restrike detection logic
0
T
RST
SETTING
BREAKER RESTRIKE 1
RESET DELAY
0
T
RST
0
T
RST
FLEXLOGIC OPERANDS
BKR RESTRIKE 1 OP A
BKR RESTRIKE 1 OP B
BKR RESTRIKE 1 OP C
BKR RESTRIKE 1 OP
FLEXLOGIC OPERAND
OR
834012A1.CDR