Schweitzer Engineering Laboratories SEL-421-4 - Table 5.10 ESS:= Y, Tapped Line; Table 5.11 ESS:= Y, Current Polarizing Source; Figure 5.11 ESS:= Y, Single Circuit Breaker with Current Polarizing Source Tapped Power Transformer

5.13
Date Code 20171021 Instruction Manual SEL-421 Relay
Protection Functions
Current and Voltage Source Selection
Single Circuit Breaker With Current Polarizing Source
Figure 5.11 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
Ta p p e d P owe r Tra n sfo r m er
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