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5.151
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Functions
Circuit Breaker Failure Protection
Retrip Scheme Y2 Three Pole (Setting EBFL = Y2)
The logic shown in
applies to three-pole breaker configurations.
Scheme Y2 is similar to Scheme 2, but the current check (50FA1) is now part of
the Retrip Time delay (RTPU1).
Retrip Scheme 2 Single Pole (Setting EBFL = 2)
illustrates the current-supervised single-pole retrip logic
(EBFL = 2). Timer RTPU1 (Breaker 1 Retrip Time Delay on Pickup Timer)
begins timing when initiation Relay Word bit BFIA1 asserts. Relay Word bit
RTA1 (Breaker 1 A-Phase Retrip) asserts immediately after timer RTPU1
expires. You can use just the RTA1 output for single-pole retrip without current
supervision. Relay Word bit RTSA1 (Breaker 1 Current Supervised A-Phase
Retrip) asserts if 50FA1 is picked up.
Figure 5.109
Scheme 2 Current-Supervised Three-Pole Retrip Logic
50FA1
50FB1
50FC1
BFIA1
RTS3P1
RT1
RT3P1
(Relay Word Bit)
BFIB1
BFIC1
RTSA1
RTSB1
RTSC1
Relay
Word
Bits
Relay
Word
Bit
SEL
OGIC
Settings
RT3PPU1
0
2 of 3
Figure 5.110
Scheme Y2 Current-Supervised Three-Pole Retrip Logic
50FA1
50FB1
50FC1
BFIA1
RTS3P1
RT1
BFIB1
BFIC1
RTSA1
RTSB1
RTSC1
Relay
Word
Bits
Relay
Word
Bit
SEL
OGIC
Settings
RT3PPU1
0
2 of 3
Figure 5.111
Scheme 2 Current-Supervised Single-Pole Retrip Logic
BFIA1
BFIB1
BFIC1
RTA1
50FA1
RTSA1
Relay
Word
Bit
Relay
Word
Bits
SEL
OGIC
Settings
RTPU1
0
2 of 3
Содержание SEL-421-4
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