Sel SEL-421 - Page 235

R.2.67
Date Code 20111215 Reference Manual SEL-421 Relay
Auto-Reclosing and Synchronism Check
Synchronism Check
Figure 2.32 Alternative Synchronism-Check Source 2 Example and
Settings
For example, in Figure 2.32, the Bus 2 voltage is the regular
Synchronism-Check Voltage Source 2 for synchronism check across
Circuit Breaker BK2. However, if Circuit Breaker BK3 is open and the
generator switch is closed, the Synchronism-Check Voltage Source 2
transfers to the alternative Synchronism-Check Voltage Source 2 the
voltage from the generator position.
For circuit breaker status, make the following 52A auxiliary contact
connections from the circuit breaker and switch to control inputs on
the SEL-421:
➤ Circuit breaker BK3 to IN103
➤ Generator switch to IN104
These input connections are for this application example only; use
relay inputs that are appropriate for your system.
Set the ALTS2 SEL
OGIC control equation to assert when Circuit
Breaker BK3 is open and the generator switch is closed.
ALTS2 := NOT IN103 AND IN104 Alternative Synchronism Source 2
(SEL
OGIC Equation)
Bus 1
Line
Switch
SYNCS2 — designate voltage input
KS2M — adjust magnitude to reference
KS2A — adjust angle to reference
Bus 2
BK2 BK3
BK1
Generator
Synchronism-Check Voltage Source 2
ASYNCS2 — designate voltage input
AKS2M — adjust magnitude to reference
AKS2A — adjust angle to reference
ALTS2 — enable alternative source 2
Alternative Synchronism-Check Voltage Source 2
1
3
1
1