x List of Figures
SEL-351A Relay Instruction Manual Date Code 20080213
Figure 3.7 Levels 1 Through 4 Phase-to-Phase Instantaneous Overcurrent Elements ............................3.9
Figure 3.8 Levels 1 Through 4 Neutral-Ground Instantaneous Overcurrent Elements
(With Directional Control and Definite-Time Elements in SEL-351A) ...........................3.10
Figure 3.9 Levels 5 Through 6 Neutral-Ground Instantaneous Overcurrent Elements .........................3.10
Figure 3.10 Levels 1 Through 4 Residual-Ground Instantaneous Overcurrent Elements
(With Directional Control and Definite-Time Elements in SEL-351A) ...........................3.12
Figure 3.11 Levels 5 Through 6 Residual-Ground Instantaneous Overcurrent Elements .......................3.12
Figure 3.12 Levels 1 Through 4 Negative-Sequence Instantaneous Overcurrent Elements
(With Directional Control and Definite-Time Elements in SEL-351A) ...........................3.15
Figure 3.13 Levels 5 Through 6 Negative-Sequence Instantaneous Overcurrent Elements ....................3.15
Figure 3.14 Phase Time-Overcurrent Element 51PT (With Directional Control Option in SEL-351A).3.17
Figure 3.15 A-Phase Time-Overcurrent Element 51AT
(With Directional Control Option in SEL-351A) .............................................................3.21
Figure 3.16 B-Phase Time-Overcurrent Element 51BT
(With Directional Control Option in SEL-351A) .............................................................3.21
Figure 3.17 C-Phase Time-Overcurrent Element 51CT
(With Directional Control Option in SEL-351A) .............................................................3.22
Figure 3.18 Neutral-Ground Time-Overcurrent Element 51NT
(With Directional Control Option in SEL-351A) .............................................................3.22
Figure 3.19 Residual-Ground Time-Overcurrent Element 51GT
(With Directional Control Option in SEL-351A) .............................................................3.24
Figure 3.20 Residual-Ground Time-Overcurrent Element 51G2T (With Directional Control Option) ..3.25
Figure 3.21 Negative-Sequence Time-Overcurrent Element 51QT
(With Directional Control Option in SEL-351A) .............................................................3.26
Figure 3.22 Single-Phase and Three-Phase Voltage Elements (Wye-Connected PTs)............................3.31
Figure 3.23 Phase-to-Phase and Sequence Voltage Elements (Wye-Connected PTs) .............................3.32
Figure 3.24 Phase-to-Phase Voltage Elements (Delta-Connected PTs)...................................................3.33
Figure 3.25 Sequence Voltage Elements (Delta-Connected PTs)............................................................3.33
Figure 3.26 Channel VS Voltage Elements (Wye- or Delta-Connected PTs)..........................................3.34
Figure 3.27 Synchronism Check Voltage Window and Slip Frequency Elements ..................................3.38
Figure 3.28 Synchronism Check Elements ..............................................................................................3.39
Figure 3.29 Angle Difference Between V
P
and V
S
Compensated by Breaker Close Time
(f
P
< f
S
and V
P
Shown as Reference in This Example) ....................................................3.45
Figure 3.30 Undervoltage Block for Frequency Elements (Group Setting VNOM ≠ OFF)....................3.49
Figure 3.31 Undervoltage Block for Frequency Elements (Group Setting VNOM = OFF)....................3.49
Figure 3.32 Levels 1 Through 6 Frequency Elements .............................................................................3.50
Figure 4.1 Loss-of-Potential Logic ..........................................................................................................4.1
Figure 4.2 Load-Encroachment Logic .....................................................................................................4.4
Figure 4.3 Migration of Apparent Positive-Sequence Impedance for a Fault Condition.........................4.7
Figure 4.4 General Logic Flow of Directional Control for Neutral-Ground and Residual-Ground
Overcurrent Elements (Excluding Ungrounded/High-Impedance Grounded Systems) ...4.10
Figure 4.5 General Logic Flow of Directional Control for Neutral-Ground and
Residual-Ground Overcurrent Elements (Ungrounded/High-Impedance
Grounded Systems; ORDER = U) ....................................................................................4.11
Figure 4.6 Internal Enables (32QE and 32QGE) Logic for Negative-Sequence Voltage-Polarized
Directional Elements.........................................................................................................4.18
Figure 4.7 Internal Enables (32VE and 32IE) Logic for Zero-Sequence Voltage-Polarized
and Channel IN Current-Polarized Directional Elements.................................................4.19
Figure 4.8 Internal Enable (32NE) Logic for Zero-Sequence Voltage-Polarized Directional
Elements (Low-Impedance Grounded, Petersen Coil Grounded, and
Ungrounded/High-Impedance Grounded Systems) ..........................................................4.20
Figure 4.9 Negative-Sequence Voltage-Polarized Directional Element for Neutral-Ground and
Residual-Ground Overcurrent Elements...........................................................................4.21
Figure 4.10 Zero-Sequence Voltage-Polarized Directional Element .......................................................4.22
Figure 4.11 Channel IN Current-Polarized Directional Element.............................................................4.23
Figure 4.12 Zero-Sequence Voltage-Polarized Directional Element
(Low-Impedance Grounded Systems)...............................................................................4.24
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