Sel 421 - Figure 1.6 Double Circuit Breaker Configuration with Bus Protection (ESS:= 4); Figure 1.7 Tapped Line (ESS:= Y)

U.1.10
SEL-421 Relay User’s Guide Date Code 20090715
Introduction and Specifications
Applications
Figure 1.6 Double Circuit Breaker Configuration With Bus Protection
(ESS := 4)
Figure 1.7 Tapped Line (ESS := Y)
SEL-421 Relay
BUS 1 BUS 2
CB1 CB2
33
3
3
IW
IX
VAZ
VY
VBZ
1
1
Analog Input
IW+IX
IW
IX
VY
VAZ
VBZ
Function
CB2 protection
Line protection
CB1 protection
Line protection
Synchronism check Circuit Breaker 1
Synchronism check Circuit Breaker 2
(HV)
Tripping
Direction
(LV)
MOD
SEL-421 Relay
IW
VY
1
1
3
3
VAZ
VBZ
CB2CB1
Analog Input
IW
VY
VAZ
VBZ
Function
Line protection
Line protection
Synchronism check Circuit Breaker 1
Synchronism check Circuit Breaker 2
Courtesy of NationalSwitchgear.com