Negative Phase Sequence (NPS) 4
The NPS elements are driven by the NPS current (I2) which is calculated in real time by digitally summing the phase currents sampled every 5 ms and applying the Fortescue formula for sequence components.
_formula_0001042926.png)
An NPS pickup occurs when the measured current ≥ the NPS setting current x the NPS pickup multiplier. A tripping time is calculated based on the magnitude of the fault current and the settings for the active trip. While the pickup is active, tripping times are calculated for each sample. Unless the fault resets, a protection trip will ensue.
NPS pickup, reset thresholds and multiplier settings are global that is they apply to all trips. Timing is determined by settings configured individually for Trips 1...4, Single Shot and Work Tag.
Table 37 NPS Protection Configuration Options
|
NPS Configuration Settings |
Range/Options |
Resolution |
Default |
|---|---|---|---|
|
Global Settings |
|||
|
Setting Current |
10 A...1260 A |
1.0 A |
40 A |
|
Pickup Multiplier |
1.0...10.0 |
0.1 |
1.0 |
|
Reset Threshold Multiplier |
90%...100% 10%...100%(1) |
1.0% |
90% |
|
Per Trip Timing Settings |
|||
|
Curve Options |
|||
|
Inverse Time Curves |
3 x IEC255 Refer Appendix D 3 x IEEE Refer Appendix E 42 x TCC Refer Appendix F Up to 5 User Defined Curves |
IEC255 Standard Inverse |
|
|
Other Curves |
Definite Time Instantaneous Only |
||
|
Inverse Time Curve Modifiers |
|||
|
Time Multiplier |
0.01...25.00 |
.01 |
1.00 |
|
Instantaneous Multiplier |
Off, 1.0...30.0 |
0.1 |
Off |
|
Minimum Time |
0.00...2.00 s |
0.01 s |
0.00 s |
|
Additional Time |
0.00...30.00 s |
0.01 s |
0.00 s |
|
Maximum Time(2) |
Off, 0.2...180.0 s |
0.1 s |
Off |
|
Other Curves |
|||
|
Definite Time |
0.01...100.00 s |
0.01 s |
1.00 s |
|
Definite Time Instantaneous Multiplier |
Off, 1.0...30.0 s |
0.1 s |
Off |
|
Instantaneous Only |
x 1.0...x 30.0 |
0.1 |
1.0 |
|
Instantaneous Minimum Time |
0.00...2.00 s |
0.01 s |
0.00 s |
| (1) Reset Threshold Multiplier setting range is 10%...100% when Reset
Curves are available. (2) This is a global setting unless Extended Minimum Time per Curve is on. |
|||