Sel SEL-421 - Block Synchronism Check; Synchronism-Check Enable Logic; Healthy Voltage Window and Indication

R.2.59
Date Code 20111215 Reference Manual SEL-421 Relay
Auto-Reclosing and Synchronism Check
Synchronism Check
Figure 2.27 Healthy Voltage Window and Indication
Block Synchronism Check
If the block synchronism check BSYNBKn SELOGIC control equation (where
n = 1 or 2 for Circuit Breaker BK1 or Circuit Breaker BK2, respectively)
asserts, synchronism check cannot proceed for the corresponding circuit
breaker. Following is an example for Circuit Breaker BK1:
BSYNBK1 := 52AA1 AND 52AB1 AND 52AC1 Block Synchronism Check—BK1
(SEL
OGIC Equation)
If Circuit Breaker BK1 is closed, the three-pole indication back to the relay
shows 52AA1 equals 52AB1 equals 52AC1 equals logical 1. Thus,
BSYNBK1 equals logical 1, and synchronism check is blocked for Circuit
Breaker BK1. There is no need to qualify or continue with the synchronism
check for circuit breaker closing; the circuit breaker is already closed.
Synchronism-Check Enable Logic
The relay combines the voltage check elements and block synchronism check
condition to create a synchronism-check enable condition for each circuit
breaker, as shown in Figure 2.28.
Figure 2.28 Synchronism-Check Enable Logic
V
S1
V
S2
25VL=60
25VH=73
59VS1 =
logical 1
59VP =
logical 1
59VS2 =
logical 1
Voltage
magnitude
(V
P
base)
Corresponding
Relay
Word Bits:
V
P
6
CYC
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
6
CYC
59VP
59VS2
BSYNBK2
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bits
V
P
healthy
V
S2
healthy
Block synchronism check for Circuit Breaker BK2
0
25ENBK2
(Enable synchronism check
for Circuit Breaker BK2)
SELOGIC
Setting