Sel 411L - Phase- and Negative-Sequence Directional Elements

P.3.152
SEL-411L Relay Protection Manual Date Code 20151029
Protection Functions
Phase- and Negative-Sequence Directional Elements
Forward Threshold
If Z0F is less than or equal to 0:
Equation 3.81
If Z0F is greater than 0:
Equation 3.82
Reverse Threshold
If Z0R is greater than or equal to 0:
Equation 3.83
If Z0R is less than 0:
Equation 3.84
32I
Directional Calculation
Equation 3.85
Forward Threshold
Equation 3.86
Reverse Threshold
Equation 3.87
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 for more details).
Z0FTH 0.75 Z0F 0.25
3V
0
I
G
----------
• –• =
Z0FTH 1.25 Z0F 0.25
3V
0
I
G
----------
• –• =
Z0RTH 0.75 Z0R 0.25
3V
0
I
G
----------
• +• =
Z0RTH 1.25 Z0R 0.25
3V
0
I
G
----------
• +• =
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• • =