Sel SEL-421 - Inverse-Time Overcurrent Elements

R.1.70
SEL-421 Relay Reference Manual Date Code 20111215
Protection Functions
Inverse-Time Overcurrent Elements
Figure 1.47 Negative-Sequence Instantaneous/Directional Overcurrent
Elements
Inverse-Time Overcurrent Elements
The SEL-421 provides three selectable operating quantity inverse-time
overcurrent elements. Ten different time-overcurrent characteristics (5 US and
5 IEC curves) are available.
Each time-overcurrent element can be configured to operate on the line
current (i.e., IW-terminal current or the sum of the IW and IX terminal
currents) depending upon setting LINEI (line Current Source); or circuit
breaker operating quantities, with the terminal source depending upon settings
BK1I and BK2I.
67Q1D
0
—
+
50Q1
67Q1
67Q1T
3I2L
50Q1P
(Setting)
67Q1TC
(SEL
OGIC
Setting)
32QF
(Relay
Word Bit)
Relay
Word
Bits
67Q2D
0
—
+
50Q2
67Q2
67Q2T
50Q2P
(Setting)
67Q2TC
(SEL
OGIC
Setting)
32QF
(Relay
Word Bit)
67Q3D
0
—
+
50Q3
67Q3
67Q3T
50Q3P
(Setting)
DIR3 := F
(Setting)
67Q3TC
(SEL
OGIC
Setting)
32QF
(Relay
Word Bit)
32QR
(Relay
Word Bit)
67Q4D
0
—
+
50Q4
67Q4
67Q4T
50Q4P
(Setting)
DIR4 := F
(Setting)
67Q4TC
(SEL
OGIC
Setting)
32QF
(Relay
Word Bit)
32QR
(Relay
Word Bit)