Schweitzer Engineering Laboratories SEL-251 - Time Delayed Variables ST, KT, and ZT; Figure 2.7: Relay Word Bit Realizations

Date Code 20000421 Specifications 2-15
SEL-251, -2, -3 Instruction Manual
PDEM
Phase demand current threshold exceeded
QDEM
Negative-sequence demand current threshold exceeded
NDEM
Ground/Residual demand current threshold exceeded
TF
Trip failure condition
CF
Close failure condition
TCMA
Trip circuit monitor alarm: asserts for abnormal open or short circuit in the circuit
breaker tripping circuit or circuit breaker status input
ST
Output from timer TS, driven by any OR-combination of elements in R1 through
R3 assigned to setting S
TRIP
Follows state of the TRIP output contacts
A B C D
Select any OR-combination of elements in R1 and R2
E F G H
Select any OR-combination of elements in R3 and R4
J
Select any OR-combination of elements in R1 through R4
KT
Output from timer TK, driven by any selected OR-combination of elements in R1
through R4 assigned to setting K
!L
Output from an inverter, driven by any selected OR-combination of elements in
R1 through R4 assigned to setting L
V W X Y Select any AND-combination of elements A through !L
ZT Output from timer TZ, driven by any selected AND-combination of elements A
through !L assigned to setting Z
Time Delayed Variables ST, KT, and ZT
Relay Word variables ST, KT, and ZT are outputs from time delay pickup/dropout timers TS,
TK and TZ, respectively. TS and TK are driven by any OR-combination of Relay Word
elements in R1...R3 and R1...R4, respectively. Any AND-combination of Relay Word elements
A through !L may drive timer TZ.
Figure 2.7: Relay Word Bit Realizations