5.129
Date Code 20171021 Instruction Manual SEL-421 Relay
Protection Functions
Permissive Overreaching Transfer Tripping Scheme
27CWI C-Phase undervoltage condition
WFC Weak-infeed detected
KEY1 Transmit permission to single-pole trip
KEY3 Transmit permission to three-pole trip
Figure 5.93 Permissive Trip Receiver Logic Diagram
Table 5.73 POTT Relay Word Bits (Sheet 2 of 2)
Name Description
PT
To POTT
Logic
Relay
Word Bit
PTDRX
Relay
Word Bit
PTDIR
Relay
Word Bit
ECOMM := POTT
Setting
ECOMM := DCUB1
ECOMM := DCUB2
PT1
PT2
ECOMM := POTT2
Setting
EPTDIR := Y
Setting
Setting
Setting
Control Input
Assignments