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5.45
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Functions
Phase and Negative-Sequence Directional Elements
32I
Directional Calculation
Equation 5.25
Forward Threshold
Equation 5.26
Equation 5.27
Phase and Negative-Sequence Directional Elements
Phase (32P) and negative-sequence voltage-polarized (32Q) directional elements
supervise the phase-distance elements. 32Q has priority over 32P. Relay Word bit
ZLOAD (Load Impedance Detected) disables the 32P element. The 32Q element
operates for all unbalanced faults.
When E32 := AUTO or AUTO2, you do not need to enter settings for 32Q or 32P
elements. However, if you set E32 (Directional Control) to Y, the settings you
enter for 50FP, 50RP, Z2F, Z2R, and a2 affect the 32Q element (see
Directional Element on page 5.33
for more details).
where:
I
P
= Polarizing Current
32I
Re I
G
I
P
•
*
=
32IFTH
0.01
InX nominal rating
nominal current rating
• •
=
32IRTH
0.01
–
InX nominal rating
nominal current rating
• •
=
Table 5.39
Phase and Negative-Sequence Directional Elements Relay Word Bits
Name
Description
F32P
Forward phase directional declaration
R32P
Reverse phase directional declaration
F32Q
Forward negative-sequence directional declaration
R32Q
Reverse negative-sequence directional declaration
32QF
Forward negative-sequence overcurrent directional declaration
32QR
Reverse negative-sequence overcurrent directional declaration
HSDQF
Phase-to-phase fault, high-speed forward directional element
HSDQR
Phase-to-phase fault, high-speed reverse directional element
Summary of Contents for SEL-421-4
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