Date Code 20001006 Overcurrent, Voltage, Synchronism Check, Frequency, and Power Elements 3-11
SEL-351 Instruction Manual
Figure 3.9: Levels 5 Through 6 Neutral Ground Instantaneous Overcurrent Elements
Settings Ranges
Setting range for pickup settings 50N1P through 50N6P:
0.250 - 100.000 A secondary (5 A nominal channel IN current input)
0.050 - 20.000 A secondary (1 A nominal channel IN current input)
0.005 - 1.500 A secondary (0.05 A nominal channel IN current input)
Setting range for definite-time settings 67N1D through 67N4D:
0.00 - 16000.00 cycles, in 0.25-cycle steps
Setting range for definite-time setting 67N2SD (used in DCB logic):
0.00 - 60.00 cycles, in 0.25-cycle steps
Note: If channel IN is rated 0.05 A nominal, then there is an additional 2-cycle time delay on all
the neutral ground instantaneous (50N1 - 50N6, 67N1 - 67N6) and definite-time (67N1T -
67N4T) elements. Any time delay provided by the definite-time settings (67N1D -
67N4D) is in addition to this 2-cycle time delay.
Accuracy
Pickup: ±0.05 A secondary and ±3% of setting (5 A nominal channel IN current input)
±0.01 A secondary and ±3% of setting (1 A nominal channel IN current input)
±1 mA secondary and ±5% of setting (0.05 A nominal channel IN current input)
Timer: ±0.25 cycles and ±0.1% of setting
Transient Overreach: ±5% of setting
Pickup and Reset Time Curves
See Figure 3.5 and Figure 3.6.
Courtesy of NationalSwitchgear.com
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