Monitoring Elements - GE N60 UR Series Instruction Manual

5.6 CONTROL ELEMENTS
a) VT FUSE FAILURE
PATH: SETTINGS CONTROL ELEMENTS
VT FUSE FAILURE 1
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
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.
5
SETTING
VT FUSE FAILURE
FUNCTION:
Disabled=0
Enabled=1
SOURCE 1
V_2
V_1
I_1
FLEXLOGIC OPERAND
SRC1 50DD OP
FLEXLOGIC OPERAND
OPEN POLE OP
D60, L60, and L90 only
5-150

MONITORING ELEMENTS

VT FUSE FAILURE 1
FUNCTION: Disabled
COMPARATORS
RUN
V_2 > 0.1 p.u.
RUN
V_1 < 0.05 p.u.
AND
RUN
I_1 > 0.075 p.u.
RUN
V_1 < 0.7 p.u.
AND
RUN
I_1 < 0.05 p.u.
AND
AND
AND
Figure 5–70: VT FUSE FAIL SCHEME LOGIC
N60 Network Stability and Synchrophasor Measurement System
VT FUSE FAILURE 1(6)
Range: Disabled, Enabled
AND
OR
AND
AND
OR
OR
2 CYCLES AND
20 CYCLES
OR
5 SETTINGS
5.6.9 MONITORING ELEMENTS
BLOCK
Reset-dominant
SET
FAULT
LATCH
RESET
SET
FUSE
FAIL
FLEXLOGIC OPERANDS
LATCH SRC1 VT FUSE FAIL OP
SRC1 VT FUSE FAIL DPO
RESET
Reset-dominant
FLEXLOGIC OPERAND
SRC1 VT FUSE FAIL VOL LOSS
827093AK.CDR
GE Multilin
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