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5.128
SEL-421 Relay
Instruction Manual
Date Code 20171021
Protection Functions
Permissive Overreaching Transfer Tripping Scheme
ETDPU
Echo Time Delay Pickup (cycles)
0.000–16000
2.000
EDURD
Echo Duration Time Delay (cycles)
0.000–16000
4.000
EWFC
Weak Infeed Trip
Y, N, SP
N
27PWI
a
Weak Infeed Phase Undervoltage Pickup (V)
1.0–200
47.0
27PPW
b
Weak Infeed Undervoltage Pickup (VFF)
0.1–300
80.0
59NW
Weak Infeed Zero-Sequence Overvoltage Pickup (V)
0.1–200
5.0
PT1
General Permissive Trip Received (when ECOMM = POTT or POTT2)
SEL
OGIC
Equation
IN102 AND PLT02
PT3
Three-Pole Permissive Trip Received (when ECOMM = POTT2)
SEL
OGIC
Equation
NA
PTA
A-Phase Permissive Trip Received (when ECOMM = POTT3)
SEL
OGIC
Equation
NA
PTB
B-Phase Permissive Trip Received (when ECOMM = POTT3)
SEL
OGIC
Equation
NA
PTC
C-Phase Permissive Trip Received (when ECOMM = POTT3)
SEL
OGIC
Equation
NA
EPTDIR
Enable Directional Element Permissive Trip
SEL
OGIC
Equation
NA
PTDIR
Directional Element Permissive Trip Received
SEL
OGIC
Equation
NA
COMZDTC
Directional Element Communications-assisted Trip Enable
SEL
OGIC
Equation
NA
a
Make setting when EWFC := SP.
b
Make setting when EWFC := Y or SP.
Table 5.72
POTT Settings (Sheet 2 of 2)
Setting
Prompt
Range
Default (5 A)
Table 5.73
POTT Relay Word Bits (Sheet 1 of 2)
Name
Description
PT
Permission to trip received (ECOMM = POTT or POTT2)
PTA
A-Phase permissive trip received (ECOMM = POTT3)
PTB
B-Phase permissive trip received (ECOMM = POTT3)
PTC
C-Phase permissive trip received (ECOMM = POTT3)
EPTDIR
Directional element permissive trip enabled (ECOMM = POTT)
PTDIR
Directional element permissive trip received enabled (PTDIR = Y)
COMZDTC Directional element communications-assisted trip torque equation asserted
(PTDIR = Y)
Z3RB
Current reversal guard asserted (ECOMM = POTT or POTT2)
Z3RBA
A-Phase current reversal guard asserted (ECOMM = POTT3)
Z3RBB
B-Phase current reversal guard asserted (ECOMM = POTT3)
Z3RBC
C-Phase current reversal guard asserted (ECOMM = POTT3)
KEY
Transmit permission to trip (ECOMM = POTT or POTT2)
KEYA
Transmit A-Phase permissive trip (ECOMM = POTT3)
KEYB
Transmit B-Phase permissive trip (ECOMM = POTT3)
KEYC
Transmit C-Phase permissive trip (ECOMM = POTT3)
EKEY
Echo received permission to trip (ECOMM = POTT or POTT2)
EKEYA
A-Phase echo received permissive trip signal (ECOMM = POTT3)
EKEYB
B-Phase echo received permissive trip signal (ECOMM = POTT3)
EKEYC
C-Phase echo received permissive trip signal (ECOMM = POTT3)
ECTT
Echo conversion to trip (ECOMM = POTT or POTT2)
27AWI
A-Phase undervoltage condition
27BWI
B-Phase undervoltage condition
Summary of Contents for SEL-421-4
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