R.1.95
Date Code 20111215 Reference Manual SEL-421 Relay
Protection Functions
Permissive Overreaching Transfer Tripping Scheme
PT1 General Permissive Trip Received
(when ECOMM = POTT or POTT2)
SELOGIC 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
a
Make setting when EWFC := SP
b
Make setting when EWFC := Y or SP
Tabl e 1 . 67 POT T Relay Word Bi t s
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)
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
27CWI C-phase undervoltage condition
WFC Weak-infeed detected
KEY1 Transmit permission to single-pole trip
KEY3 Transmit permission to three-pole trip
Tabl e 1 . 66 POT T Set tin gs (Sheet 2 of 2)
Setting Description Range
Default
(5 A)
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