Date Code 20001006 Loss-of-Potential, Load Encroachment, and Directional Element Logic 4-27
SEL-351 Instruction Manual
Settings
DIR1 – Level 1 Overcurrent Element Direction Setting
DIR2 – Level 2 Overcurrent Element Direction Setting
DIR3 – Level 3 Overcurrent Element Direction Setting
DIR4 – Level 4 Overcurrent Element Direction Setting
Setting Range:
F = Direction Forward
R = Direction Reverse
N = Nondirectional
Table 4.1 shows the overcurrent elements that are controlled by each level direction setting. Note
in Table 4.1 that all the time-overcurrent elements (51_T elements) are controlled by the DIR1
level direction setting. Figure 4.12, Figure 4.17, and Figure 4.18 show the logic implementation of
the control listed in Table 4.1.
Table 4.1: Overcurrent Elements Controlled by Level Direction Settings DIR1 Through
DIR4 (Corresponding Overcurrent Element Figure Numbers in Parentheses)
Level Direction
Settings Phase
Neutral
Ground
Residual
Ground
Negative-
Sequence
DIR1
67P1 (3.3)
67P1T (3.3)
51PT (3.14)
51AT (3.15)
51BT (3.16)
51CT (3.17)
67N1 (3.8)
67N1T (3.8)
51NT (3.18)
67G1 (3.10)
67G1T (3.10)
51GT (3.19)
67Q1 (3.12)
67Q1T (3.12)
51QT (3.20)
DIR2
67P2 (3.3)
67P2T (3.3)
67P2S (3.3)
67N2 (3.8)
67N2T (3.8)
67N2S (3.8)
67G2 (3.10)
67G2T (3.10)
67G2S (3.10)
67Q2 (3.12)
67Q2T (3.12)
67Q2S (3.12)
DIR3
67P3 (3.3)
67P3T (3.3)
67N3 (3.8)
67N3T (3.8)
67G3 (3.10)
67G3T (3.10)
67Q3 (3.12)
67Q3T (3.12)
DIR4
67P4 (3.3)
67P4T (3.3)
67N4 (3.8)
67N4T (3.8)
67G4 (3.10)
67G4T (3.10)
67Q4 (3.12)
67Q4T (3.12)
In most communications-assisted trip schemes, the levels are set as follows (see Figure 5.4):
Level 1 overcurrent elements set direction forward (DIR1 = F)
Level 2 overcurrent elements set direction forward (DIR2 = F)
Level 3 overcurrent elements set direction reverse (DIR3 = R)
Courtesy of NationalSwitchgear.com
To Next Page
Loading...
