5.5
Date Code 20171021 Instruction Manual SEL-421 Relay
Protection Functions
Current and Voltage Source Selection
Current Source Uses
Refer to the global settings in Table 8.13 on page 8.5. Line-current source setting
LINEI and alternate line-current source settings ALINEI and ALTI, if used, iden-
tify the currents used in the following elements/features described later in this
section and in other sections:
➤ Fault location
➤ Open-phase detection logic
➤ LOP (loss-of-potential) logic
➤ FIDS (fault-type identification selection) logic
➤ Directional elements
➤ CVT (capacitor voltage transformer) transient detection logic
Table 5.3 Available Current Source Selection Settings Combinations When ESS := Y, NUMBK := 2
a
a
NA = not applicable.
NUMBK
(number of
breakers)
ESS
(source
selection)
LINEI
(line-current
source)
ALINEI
(alternate line-
current source)
BK1I
(Breaker 1
current source)
BK2I
(Breaker 2
current source)
IPOL
(polarizing
current)
2 Y IW IX IW IX NA
2 Y IW IX IW COMB NA
2 Y IW IX IW NA NA
2 Y IW IX IX COMB NA
2 Y IW IX IX NA NA
2 Y IW IX NA IX NA
2 Y IW IX NA COMB NA
2 Y IW IX NA NA NA
2 Y IW NA IW IX NA
2 Y IW NA IW COMB NA
2 Y IW NA IW NA IAX, IBX, ICX,
or NA
2 Y IW NA IX COMB NA
2 Y IW NA IX NA NA
2 Y IW NA NA IX NA
2 Y IW NA NA COMB NA
2 Y IW NA NA NA IAX, IBX, ICX,
or NA
2 Y COMB IX IW IX NA
2 Y COMB IX IW NA NA
2 Y COMB IX IX NA NA
2YCOMBIXNAIXNA
2 Y COMB IX NA NA NA
2YCOMBNAIWIXNA
2 Y COMB NA IW NA NA
2 Y COMB NA IX NA NA
2 Y COMB NA NA IX NA
2 Y COMB NA NA NA NA