Date Code 20001006 Overcurrent, Voltage, Synchronism Check, Frequency, and Power Elements 3-53
SEL-351 Instruction Manual
Table 3.11: Frequency Elements Settings and Settings Ranges
Setting Definition Range
27B81P undervoltage frequency element block 12.50 - 150.00 V secondary (wye-
connected voltages, {150 V voltage
inputs})
25.00 - 300.00 V secondary (wye-
connected voltages, {300 V voltage
inputs})
34.00 - 260.00 V secondary
(delta-connected voltages)
81D1P frequency element 1 pickup 40.10 - 65.00 Hz
81D1D frequency element 1 time delay 2.00 - 16000.00 cycles, in
0.25-cycle steps
81D2P frequency element 2 pickup 40.10 - 65.00 Hz
81D2D frequency element 2 time delay 2.00 - 16000.00 cycles, in
0.25-cycle steps
81D3P frequency element 3 pickup 40.10 - 65.00 Hz
81D3D frequency element 3 time delay 2.00 - 16000.00 cycles, in
0.25-cycle steps
81D4P frequency element 4 pickup 40.10 - 65.00 Hz
81D4D frequency element 4 time delay 2.00 - 16000.00 cycles, in
0.25-cycle steps
81D5P frequency element 5 pickup 40.10 - 65.00 Hz
81D5D frequency element 5 time delay 2.00 - 16000.00 cycles, in
0.25-cycle steps
81D6P frequency element 6 pickup 40.10 - 65.00 Hz
81D6D frequency element 6 time delay 2.00 - 16000.00 cycles, in
0.25-cycle steps
Accuracy
Pickup: ±0.01 Hz
Timer: ±0.25 cycles and ±0.1% of setting
Create Over- and Underfrequency Elements
Refer to Figure 3.30.
Note that pickup settings 81D1P through 81D6P are compared to setting NFREQ. NFREQ is the
nominal frequency setting (a global setting), set to 50 or 60 Hz.
Courtesy of NationalSwitchgear.com
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