| Protection | IEC symbol (IEC60617) | ANSI (IEEE C37.2) | Operate time |
|---|---|---|---|
| Neutral inverse time over-current | 50N | - |
|
This is the inverse time over-current alarm for the neutral current measurement. The alarm response is based on the unfiltered (except for anti-aliasing) neutral current, as measured by the 4th current measurement. The alarm response time depends on an approximated integral of the current measurement over time. The integral is only updated when the measurement is above the activation threshold. Note: The diagram on the right is a simplified representation of
this alarm. The diagram does not show the integral over time.
|
Common protect > Current protections > Neut. inv. t.
o-curr.
| Parameter | Text | Range | Default |
|---|---|---|---|
| 1721 | Type |
IEC Inverse IEC Very Inverse IEC Extremely Inv. IEEE Moderately Inv. IEEE Very Inverse IEEE Extremely Inv. Custom |
IEC Inverse |
| 1722 | Set point | 2 to 120 % | 30 % |
| 1723 | Set point TMS | 0.01 to 100.00 s | 1.00 |
| 1724 | Set point k | 0.001 to 32.000 s | 0.140 s |
| 1725 | Set point c | 0.000 to 32.000 s | 0.000 s |
| 1726 | Set point a | 0.001 to 32.000 s | 0.020 s |
| 1728 | Enable |
OFF ON |
OFF |
| 1727 | Fail class | Fail classes | Trip CB1 |
Fastpath: See Inverse time over-current (ANSI 51) in the AGC 150
Generator, Mains and BTB Designer's Handbook for the calculation method, the
standard curves, and information about the definite time characteristic.