Monitoring Elements - GE G60 Instruction Manual

5 SETTINGS
a) VT FUSE FAILURE
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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 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
VT FUSE FAILURE 1(4) FUNCTION
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 only
GE Multilin
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MONITORING ELEMENTS

VT FUSE FAILURE 1
FUNCTION: Disabled
setting enables/disables the fuse failure feature for each source.
COMPARATORS
RUN
V_2 > 0.25 p.u.
RUN OR
V_1 < 0.05 p.u.
AND
RUN
I_1 > 0.075 p.u.
RUN
V_1 < 0.7 p.u.
2 CYCLES
AND
RUN
I_1 < 0.05 p.u.
AND
OR
AND
AND
Figure 5–105: VT FUSE FAIL SCHEME LOGIC
G60 Generator Management Relay
5.6.10 MONITORING ELEMENTS
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VT FUSE FAILURE 1(4)
Range: Disabled, Enabled
AND
OR
AND
AND
OR
FUSE
FAIL
AND
20 CYCLES
5.6 CONTROL ELEMENTS
Reset-dominant
SET
FAULT
LATCH
RESET
SET
FLEXLOGIC OPERANDS
LATCH SRC1 VT FUSE FAIL OP
SRC1 VT FUSE FAIL DPO
RESET
Reset-dominant
FLEXLOGIC OPERAND
SRC1 VT FUSE FAIL VOL LOSS
827093AG.CDR
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