5-98 F650 Digital Bay Controller GE Multilin
5.5 CONTROL ELEMENTS 5 SETPOINTS
5
Figure 5–27: FUSE FAILURE UNIT BLOCK DIAGRAM
5.5.8 BROKEN CONDUCTOR
F650 units incorporate a broken or fallen conductor detection function. The relay uses the ratio between the negative
sequence current, I
2
, and the positive sequence current I
1
. In normal and balanced load situations, this ratio is zero, while
in severe load fault conditions, an unbalance is produced and this ratio is increased.
Setpoint > Control Elements > Broken Conductor
Table 5–81: BROKEN CONDUCTOR UNIT SETPOINTS
This way, when the function is enabled and the unbalance is produced over the set percentage, the unit will pick up. If
unbalance conditions are maintained during a period longer than the set time delay, the unit will trip.
In order to avoid trips or pickups with very weak loads there is a current level threshold to inhibit the operation of the
unit when the three phase currents are below that fixed level.
Note: The I2/I1 current inhibition level for the different firmware versions is as follows:
SETPOINT > CONTROL ELEMENTS > VT FUSE FAILURE
SETPOINT DESCRIPTION NAME DEFAULT VALUE STEP RANGE
Function permission Function DISABLED N/A [DISABLED – ENABLED]
Tap Level in percentage of I2/I1 Tap 20.0 0.1 % [20.0 : 100.0]
Trip Time Trip Delay 60.00 0.01 s [0.00 : 900.00]
Snapshot event generation Snapshot Events ENABLED N/A [DISABLED – ENABLED]
Current Inhibition Level setpoint Operation Threshold 0.005 0.001 A [0.000 : 1.000]
FIRMWARE VERSION CURRENT INHIBITION LEVEL
1.50 or Lower 10 mA
1.60 or Higher 50 mA
1.80 or Higher Selectable by setpoint from 0.000 to 1.000 in steps of 0.001 A
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