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GBT Curve = Time curve dial setting (1 to 63).
T
, K, C, P and R are constants, and are shown in T able 3-1 .
0
Taking the CO-8 curve set as an example (see Figure 2-36), assuming that the maxi-
mum 3Io of unbalanced load is 0.2A, the minimum ground fault current for a fault two
buses away is 10A, and 0.7 seconds is required for coordination with current of 20
times the GB Pickup setting, then the settings of the ground overcurrent backup func-
tion should be as shown below:
10/2 > GB Pickup > 2 x 0.2
Choosing from the curves, in Figure 2-36, for 0.7 seconds at 20 times the GB Pickup
setting, GBT Curve should be set to 24. Set GB Type to C0-8 and set GB Dir to YES
if directional control is required.
3.3.25 Close-Into-Fault Trip Setting (CIF Trip)
Set CIF Trip setting by selecting the value field Yes if line side potential is used to sup-
ply the relay.
3.3.26 Load Loss Trip Setting (LL Trip)
Set LL Trip to YES, FDOG or NO, where:
YES– LL Trip trip with Z2 supervision.
FDOG–LL Trip with both Z2 and FDOG supervision.
NO–LL Trip function is not used.
3.3.27 Loss of Potential Block Setting (LOP Blk)
Set LOP Blk to YES, if loss-of-potential block trip function is required.
3.3.28 Loss of Current Block Setting (LOI Blk)
Set LOI Blk to YES, if loss-of-current block trip function is required.
3.3.29 Trip Alarm Setting (Trip Alm)
Set Trip Alm to Seal-in, if trip alarm seal-in is required. The front panel, reset push-
button can be used to reset the sealed alarm.
3.3.30 Remote Setting (Rem. Set)
Set the Rem. Set to Remote Allowed if remote setting (via communications port) is
required.
3.3.31 Real-Time Clock Setting
With REL 301/302 in the "setting" mode, scroll the function field to Time Set, and
change the value to YES. Depress function pushbutton RAISE to display Year, Month,
Day, Weekday, Hour, and Minute, and set the corresponding number via the value
(10/94)
set GB Pickup = 0.5
I.L. 40-386.3
3-13
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