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5.13
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Functions
Current and Voltage Source Selection
Single Circuit Breaker With Current Polarizing Source
shows a single circuit breaker situated by an autotransformer. The
SEL-421 uses the delta-connected tertiary as a current polarizing source for the
zero-sequence current-polarized directional element 32I. For example, connect to
current to input IAX (set IPOL
:
= IAX).
Table 5.10
ESS := Y, Tapped Line
Setting
Prompt
Entry
Comments
NUMBK
Number of Circuit Breakers in Scheme (1, 2)
2
LINEI
Line Current Source (IW, COMB)
IW
ALINEI
Alternate Current Source (IX, NA)
NA
ALTI
Alternate Current Source (SEL
OGIC
Equation)
NA
Hidden
a
a
Hidden when preceding setting is NA.
BK1I
Breaker 1 Current Source (IW, IX, NA)
NA
BK2I
Breaker 2 Current Source (IX, COMB, NA)
NA
IPOL
Polarizing Current (IAX, IBX, ICX, NA)
NA
ALINEV
Alternate Line Voltage Source (VZ, NA)
NA
Default
ALTV
Alternate Voltage Source (SEL
OGIC
Equation)
NA
Hidden
Figure 5.11
ESS := Y, Single Circuit Breaker With Current Polarizing Source
Tapped Power Transformer
Table 5.11
ESS := Y, Current Polarizing Source (Sheet 1 of 2)
Setting
Prompt
Entry
Comments
NUMBK
Number of Circuit Breakers in Scheme (1, 2)
1
LINEI
Line Current Source (IW, COMB)
IW
ALINEI
Alternate Current Source (IX, NA)
NA
SEL-421 Relay
BUS
CB
IW
VAZ
IAX
(Delta-Connected Tertiary)
VY
3
1
Analog Input
IW
IAX
VY
VAZ
Function
Line protection
Ground directional element current polarization
Line protection
Synchronism check
Summary of Contents for SEL-421-4
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