5.8
SEL-421 Relay Instruction Manual Date Code 20171021
Protection Functions
Current and Voltage Source Selection
ESS := N, Single Circuit Breaker Configuration—One Current Input
Set ESS to N for single circuit breaker applications with one current input.
Figure 5.5 illustrates this application along with the corresponding current and
voltage sources. When ESS equals N, you cannot use alternate sources (ALINEI
and ALINEV) and the relay hides the Global settings LINEI, ALINEI, ALTI,
BK1I, BK2I, IPOL, ALINEV, and ALTV.
ESS := 1, Single Circuit Breaker Configuration—One Current Input
Set ESS to 1 for single circuit breaker applications with one current input.
Figure 5.5 illustrates this application along with the corresponding current and
voltage sources.
With ESS := 1, the IX current channels have the option to be used as an alternate
line-current source (ALINEI := IX) or as a polarizing current channel (e.g.,
IPOL := IBX), but not both (see Table 5.1).
Table 5.5 ESS := N, Current and Voltage Source Selection
Setting Prompt Entry Comments
NUMBK Number of Breakers in Scheme (1, 2) 1
LINEI Line Current Source (IW, COMB) IW Hidden
BK1I Breaker 1 Current Source (IW, IX, NA) IW Hidden
BK2I Breaker 2 Current Source (IX, COMB, NA) NA Hidden
Figure 5.5 ESS := 1, Single Circuit Breaker Configuration
Table 5.6 ESS := 1, Current and Voltage Source Selection (Sheet 1 of 2)
Setting Prompt Entry Comments
NUMBK Number of Circuit Breakers in Scheme (1, 2) 1
LINEI Line Current Source (IW) IW Automatic
ALINEI Alternate Line Current Source (IX, NA) NA
ALTI Alternate Current Source (SEL
OGIC Equation) NA Hidden
a
BK1I Breaker 1 Current Source (IW) IW Automatic
BK2I Breaker 2 Current Source (NA) NA Hidden
IPOL Polarizing Current (IAX, IBX, ICX, NA) NA
SEL-421 Relay
BUS
CB1
3
3
IW
VAZ
VY
1
Analog Input
IW
VY
VAZ
Function
CB1 protection, line protection
Line protection
Synchronism check
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