Date Code 20011112
Line Current Differential, Distance, Out-of-Step, Overcurrent,
3-87
Voltage, Synchronism Check, and Frequency Elements
SEL-311L Instruction Manual
Table 3.14: Frequency Elements Settings and Settings Ranges
Setting Definition
Range
27B81P
undervoltage frequency element block
20.00–150.00 V secondary
(wye-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 3.57.
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.
Overfrequency Element
For example, make settings:
NFREQ = 60 Hz
(nominal system frequency is 60 Hz)
E81
≥
1
(enable frequency element 1)
81D1P = 61.25 Hz.
(frequency element 1 pickup)
With these settings:
81D1P
≥
NFREQ
the overfrequency part of frequency element 1 logic is enabled. 81D1 and 81D1T operate as
overfrequency elements. 81D1 is used in testing only.
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