Schweitzer Engineering Laboratories SEL-421-4 - Figure 5.127 Synchronism-Check Enable Logic

5.168
SEL-421 Relay Instruction Manual Date Code 20171021
Protection Functions
Synchronism Check
Angle Checks and Synchronism-Check Element Outputs
After the relay determines that it is appropriate to enable synchronism-check
logic as defined in Figure 5.127, the relay must check voltage phase angles
across the circuit breakers before a final synchronism-check element output can
be available for supervising circuit breaker closing.
The following discussion/examples use Circuit Breaker BK1. Synchronism-
check element output operation for Circuit Breaker BK2 is similar (replace BK2
for BK1 in associated settings and Relay Word bits).
Figure 5.127 Synchronism-Check Enable Logic
59VP
59VS1
BSYNBK1
V
P
healthy
V
S1
healthy
Block synchronism check for Circuit Breaker BK1
0
25ENBK1
(Enable synchronism check
for Circuit Breaker BK1)
SELOGIC
Setting
59VP
59VS2
BSYNBK2
Block synchronism check for Circuit Breaker BK2
0
25ENBK2
(Enable synchronism check
for Circuit Breaker BK2)
SELOGIC
Setting
V
P
healthy
V
S2
healthy
E25BK1 = Y
E25BK2 = Y
SEL
OGIC
Setting
59VDIF1
Relay
Word Bit
Relay
Word Bit
Relay
Word Bit
Relay
Word Bit
Relay
Word Bit
E25BK1 = Y1
BSYNBK1
6 cyc
6 cyc
6 cyc
0
Relay
Word Bit
25ENBK1
(Enable synchronism check
for Circuit Breaker BK1)
Block synchronism check for Circuit Breaker BK1
SEL
OGIC
Setting
59VDIF2
Relay
Word Bit
59VP
59VS1
59VDIF1
Relay
Word Bit
E25BK2 = Y1
BSYNBK2
Setting
E25BK1 = Y2
SEL
OGIC
BSYNBK1
6 cyc
0
Relay
Word Bit
25ENBK2
(Enable synchronism check
for Circuit Breaker BK2)
Block synchronism check for Circuit Breaker BK2
Block synchronism check for Circuit Breaker BK1
6 cyc
0
Relay
Word Bit
25ENBK1
(Enable synchronism check
for Circuit Breaker BK1)
59VP
59VS2
59VDIF2
Relay
Word Bit
Setting
E25BK2 = Y2
SEL
OGIC
BSYNBK2
Block synchronism check for Circuit Breaker BK2
6 cyc
0
Relay
Word Bit
25ENBK2
(Enable synchronism check
for Circuit Breaker BK2)