Schweitzer Engineering Laboratories SEL-351A - Figure 3.32 Levels 1 through 6 Frequency Elements

3.50
SEL-351A Relay Instruction Manual Date Code 20080213
Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Frequency Elements
q From Figure 3.30 or Figure 3.31; w 81D1–81D6 are for testing purposes only.
Figure 3.32 Levels 1 Through 6 Frequency Elements
(from
q
)
Frequency Element 1
(Setting E81
≥
1)
81D1P
<
NFREQ
81D1P
≥
NFREQ
81D4D
81D3D
81D2D
Measured System
Frequency (in Hz)
Undervoltage Condition
81D1T
0
81D1D
Overfrequency
Underfrequency
Overfrequency
Underfrequency
Overfrequency
Underfrequency
Overfrequency
Underfrequency
81D2
w
81D2T
0
81D3 w
81D3T
0
81D4 w
81D4T
0
27B81
Relay
Word
Bits
81D1
w
Relay
Word
Bits
Enabled
Frequency
Elements
81D1P
Settings
(in Hz)
Frequency Element 2
(Setting E81 ≥ 2)
81D2P < NFREQ
81D2P ≥ NFREQ
81D2P
Frequency Element 3
(Setting E81 ≥ 3)
81D3P < NFREQ
81D3P ≥ NFREQ
81D3P
Frequency Element 4
(Setting E81 ≥ 4)
81D4P < NFREQ
81D4P ≥ NFREQ
81D4P
81D5D
Overfrequency
Underfrequency
81D5
w
81D5T
0
Frequency Element 5
(Setting E81 ≥ 5)
81D5P < NFREQ
81D5P ≥ NFREQ
81D5P
81D6D
Overfrequency
Underfrequency
81D6
w
81D6T
0
Frequency Element 6
(Setting E81 = 6)
81D6P < NFREQ
81D6P ≥ NFREQ
81D6P
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