Earth Fault (EF)
The EF elements are driven by the residual current that is the real-time vector sum of the three phase currents. The residual or earth current is calculated by digitally summing the phase currents sampled every 5 ms.
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An EF pickup occurs when the measured current ≥ the earth setting current x the earth pickup multiplier. A tripping time is calculated based on the magnitude of the fault current and the settings for the active trip and updated every sample.
Unless the fault resets, a protection trip will ensue.
EF 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.
Configuration options for EF protection are listed in the table below.
Table 35 EF Protection Configuration Options
|
Phase overcurrent Configuration Settings |
Range/Options |
Resolution |
Default |
|---|---|---|---|
|
Global Settings |
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|
Setting Current |
10...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(1) |
Off, 0.2...180.0 s |
0.1 s |
Off |
|
Other Curves |
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|
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) This is a global setting unless Extended Minimum Time per Curve
is On. (2) Reset Threshold Multiplier setting range is 10%...100% when Reset Curves are available. |
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