Sel SEL-421 - Phase and Negative-Sequence Directional Elements

R.1.38
SEL-421 Relay Reference Manual Date Code 20111215
Protection Functions
Phase and Negative-Sequence Directional Elements
32I
Directional Calculation
Equation 1.11
Forward Threshold
Equation 1.12
Reverse Threshold
Equation 1.13
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, 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 Ground
Directional Element on page R.1.27 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 1.33 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