5.167
Date Code 20171021 Instruction Manual SEL-421 Relay
Protection Functions
Synchronism Check
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 5.127. Settings E25BK1 and E25BK2 determine
which enable logic is active.
To Next Page
Loading...
