GE C70 Instruction Manual page 365

5 SETTINGS
voltage level without disturbance in current can indicate a VT fuse fail conditions. These noted indications of fuse failure
can also be present when faults are present on the system, so a means of detecting faults and inhibiting fuse failure decla-
rations during these events is provided.
Once the fuse failure condition is declared, it is 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 FUNCTION
The
VT NEU WIRE OPEN 1 FUNCTION
VT is connected in Delta, do not enabled this function because there is no neutral wire for Delta connected VT.
The
VT NEU WIRE OPEN 1 3 HRAM PKP
WIRE OPEN detection logic to pick up.
Function voltage magnitude of one
cycle before
Enabled = 1
SOURCE 1
VA
VB
VC
V_2
V_1
I_1
FLEXLOGIC OPERANDS
SRC1 50DD OP
OPEN POLE OP
The OPEN POLE OP operand applies
to the C60, D60, L60, L90, N60
SETTING
Neutral Wire Open Detect
Enabled = 1
SOURCE 1
3V_0 (3rd Harmonic)
Base voltage for this element is PHASE VT SECONDARY setting in the case of WYE VTs and (PHASE VT SECONDARY)/
3 in case of DELTA VTs.
GE Multilin
setting enables and disables the fuse failure feature for Source 1 VT Fuse Fail.
setting enables and disables the VT neutral wire open detection function. When the
setting specifies the pickup level of 3rd harmonic of 3V0 signal for the VT NEU
COMPARATORS
Run
|VA’|-|VA| > 0.2 pu
& |VA’| > 0.8 pu
Run
|VB’|-|VB| > 0.2 pu OR
& |VB’| > 0.8 pu
Run
|VC’|-|VC| > 0.2 pu
& |VC’| > 0.8 pu
Run
V_2 > 0.1 pu
OR
Run
V_1 < 0.05 pu
AND
Run
I_1 > 0.075 pu
Run
TIMER
V_1 < 0.80 pu
2 cycles
Run
AND
I_1 < 0.05 pu
AND
OR
AND
AND
SETTING
3 HARM PKP
Run
AND
3V_0 3rd Harm >setting
Figure 5–111: VT FUSE FAIL SCHEME LOGIC
C70 Capacitor Bank Protection and Control System
OR
FUSE
FAIL
TIMER
2 cycles
SET
AND
0
Latch
20 cycles
TIMER
30 cycles
RESET
0
Reset-dominant
TIMER
5 cycles
AND
0
OR
TIMER
0
AND 20 cycles
5.7 CONTROL ELEMENTS
AND
FAULT
OR
FLEXLOGIC OPERANDS
SRC1 VT FUSE FAIL OP
SRC1 VT FUSE FAIL DPO
FLEXLOGIC OPERAND
SRC1 VT FUSE FAIL VOL LOSS
FLEXLOGIC OPERAND
SRC1 VT NEU WIRE OPEN
FLEX-ANALOG
SRC1 3V0 3nd Harmonic
827093AQ.CDR
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