GE 350-A9 User Manual

6–154 350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
S4 CONTROLS CHAPTER 6: SETPOINTS
VT fuse fail (VTFF or 60VTS)
The 350 relay includes one VT Fuse Failure element. The measured voltages from the
installed phase VTs are monitored and compared against user programmable levels. If one
or two of the three voltages drops to less than 70% of nominal, and at the same time any
of the three voltages is greater than 85%, either an Alarm or a Trip will occur after a
1
second delay. The 70% threshold allows for the possibility that the downstream voltage
from a blown fuse is pulled up above zero by devices connected between the open fuse
and another phase. The VT reference for the VTFF element is the phase to neutral voltage
for Wye-connected VTs, and the phase-phase voltage for a Delta-connected VT. The VT
Connection, VT Ratio and VT Secondary voltage are user programmable values under
SETPOINTS > S2 SYSTEM SETUP > VOLTAGE SENSING.
PATH: SETPOINTS > S4 CONTROL > VT FUSE FAILURE
FUSE FAIL FUNCTION
Range: Disabled, Alarm, Trip
Default: Trip
For details see Common setpoints
.
Figure 6-65: Fuse Fail Protection Logic Diagram
898802A1.cdr
Set Dominant
LATCH
S
R
AND
LOGIC OPERAND
Fuse Fail Trip OP
LOGIC OPERAND
Fuse Fail
1s
0
LOGIC OPERAND
Fuse Fail Alarm OP
AND
SETTING
= Disabled
= Trip
Fuse Fail Function
= Alarm
TARGET MESSAGE
Fuse Fail Alarm
State: Operate
Fuse Fail Trip
State: Operate
Any Alarm OP
Any Trip OP
RESET
Command
AND
OR
OR
VOLTAGE INPUTS
VOLTAGE INPUTS
< 70%V
a
V
ab
( )
< 70%V
b
V
bc
( )
< 70%V
c
V
ca
( )
>85%V
a
V
ab
( )
>85%V
b
V
bc
( )
>85%V
c
V
ca
( )
V
a
NOTE: The VTFF uses phase to neutral voltages , and when “Wye” VT type is selected under Voltage Sensing/VT connections setpoint, and uses
phase-phase voltages , and when “Delta” type is selected comparators.
V
b
V
c
V
ab
V
bc
V
ca

GE 350-A9 Specifications

General

Brand	GE
Model	350-A9
Category	Relays
Language	English