![Schweitzer Engineering Laboratories SEL-421-4 Instruction Manual Download Page 321](http://html.mh-extra.com/html/schweitzer-engineering-laboratories/sel-421-4/sel-421-4_instruction-manual_1216726321.webp)
5.161
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Functions
Synchronism Check
Figure 5.121
Synchronism-Check Relay Word Bits
Table 5.81
Synchronism-Check Relay Word Bits (Sheet 1 of 2)
Relay
Word Bit
Description
59VP
V
P
within healthy voltage window
59VS1
V
S1
within healthy voltage window
59VDIF1
Circuit Breaker BK1 synchronizing voltage difference less than limit
25ENBK1
Circuit Breaker BK1 synchronism-check element enabled
SFZBK1
Circuit Breaker BK1 slip frequency less than 0.005 Hz (“no slip” condition)
SFBK1
0.005 Hz
Circuit Breaker BK1 slip frequency < 25SFBK1
25W1BK1
Voltage angle across Circuit Breaker BK1 < ANG1BK1
25W2BK1
Voltage angle across Circuit Breaker BK1 < ANG2BK1
25A1BK1
Same operation as 25W1BK1, except for the restrictive operation (0° closure attempt)
when setting 25SFBK1
OFF and the system is slipping (see
25A2BK1
Same operation as 25W2BK1, except for the restrictive operation (0° closure attempt)
when setting 25SFBK1
OFF and the system is slipping (see
FAST1
Bus 1 frequency greater than line frequency (f
S1
> f
P
)
SLOW1
Bus 1 frequency less than line frequency (f
S1
< f
P
)
59VS2
V
S2
within healthy voltage window
59VDIF2
Circuit Breaker BK2 synchronizing voltage difference less than limit
25ENBK2
Circuit Breaker BK2 synchronism-check element enabled
SFZBK2
Circuit Breaker BK2 slip frequency less than 0.005 Hz (“no slip” condition)
SFBK2
0.005 Hz
Circuit Breaker BK2 slip frequency < 25SFBK2
25W1BK2
Voltage angle across Circuit Breaker BK2 < ANG1BK2
25W2BK2
Voltage angle across Circuit Breaker BK2 < ANG2BK2
Bus 2
Bus 1
Synchronism-Check Voltage Source 1
59VS1 — V
S1
healthy
Synchronism-Check Voltage Reference
59VP — V
P
healthy
Synchronism-Check Voltage Source 2
59VS2 — V
S2
healthy
Line
Synchronism-Check Across Breaker BK1
25ENBK1 — synchronism enabled
SFZBK1 — no slip
SFBK1
— slip < 25SFBK1
FAST1 —
f
S1
> f
P
SLOW1 —
f
S1
< f
P
25W1BK1 — synchronism within ANG1BK1
25A1BK1 — variation of 25W1BK1
25W2BK1 — synchronism within ANG2BK1
25A2BK1 — variation of 25W2BK1
Synchronism-Check Across Breaker BK2
25ENBK2 — synchronism enabled
SFZBK2 — no slip
SFBK2
— slip < 25SFBK2
FAST2 —
f
S2
> f
P
SLOW2 —
f
S2
< f
P
25W1BK2 — synchronism within ANG1BK2
25A1BK2 — variation of 25W1BK2
25W2BK2 — synchronism within ANG2BK2
25A2BK2 — variation of 25W2BK2
BK2
BK1
3
1
1
. . .
. . .
. . .
Summary of Contents for SEL-421-4
Page 6: ...This page intentionally left blank ...
Page 14: ...This page intentionally left blank ...
Page 30: ...This page intentionally left blank ...
Page 104: ...This page intentionally left blank ...
Page 128: ...This page intentionally left blank ...
Page 536: ...This page intentionally left blank ...
Page 584: ...This page intentionally left blank ...
Page 616: ...This page intentionally left blank ...
Page 696: ...This page intentionally left blank ...
Page 750: ...This page intentionally left blank ...
Page 755: ...Instruction Manual PM400 01 NB SEL 400 Series Relays Instruction Manual 20171006 ...
Page 776: ...This page intentionally left blank ...
Page 932: ...This page intentionally left blank ...
Page 976: ...This page intentionally left blank ...
Page 1024: ...This page intentionally left blank ...
Page 1038: ...This page intentionally left blank ...
Page 1064: ...This page intentionally left blank ...
Page 1128: ...This page intentionally left blank ...
Page 1206: ...This page intentionally left blank ...
Page 1316: ...This page intentionally left blank ...
Page 1350: ...This page intentionally left blank ...
Page 1464: ...This page intentionally left blank ...
Page 1468: ...This page intentionally left blank ...
Page 1492: ...This page intentionally left blank ...
Page 1518: ...This page intentionally left blank ...