ERL 8700/BUS, User Manual

Page: 62 / 166

4 Protection Functions
4-18 B-PRO User Manual 8700 D01908R02.12
46-50/46-51/67 Negative Sequence Overcurrent
Negative Sequence Overcurrent provides further protection for any unbal-
anced faults. This function operates fundamental I
2
quantities. Two sets of neg-
ative sequence time overcurrent protection functions on each CT input provide
directional or non-directional current detection. There is a definite time over-
current element (46-50) and an inverse time overcurrent element (46-51). You
can configure both 46-50 and 46-51 to be non-directional, forward direction,
or reverse direction sensitive. You can also configure both 46-50 and 46-51
outputs to initiate the 50BF protection element. Device 46-51 provides three
predefined IEEE, three IEC inverse time curves, and one user-defined curve.
The equation and the parameters of device 46-51 are listed below. You can se-
lect the user-defined curve type and the parameters in the equation are settable
otherwise they are fixed and determined by the curve type.
Pickup: For I > Pickup
46-50/46-51/67 Negative Sequence Overcurrent
Directional
non-directional, forward, reverse
Pickup
0.5 to 50.0 (5A)
0.1 to 10.0 (1A)
Pickup Delay
0.00 to 99.99
46-50 Breaker Failure
Initiated
enabled or disabled
Directional
non-directional, forward, reverse
Pickup
0.5 to 50.0 (5A)
0.1 to 10.0 (1A)
Curve Type
For details see Table 4.1: IEC and IEEE Curves on page 4-
14.
TMS
0.01 to 10.00
A
0.0010 to 1000.0000
B
0.0000 to 10.0000
ρ
0.01 to 10.00
TR
0.01 to 100.00
46-51 Breaker Failure
Initiated
enabled or disabled
T I
( )
TMS B
(
A
I 2
Pickup
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