Schweitzer Engineering SEL-351P - Three-Pole Open Logic

5-6 Trip and Target Logic Date Code 990215
SEL-351P Manual Técnico
Figure SECTION 5: .3: Three-Pole Open Logic (top) and Switch-Onto-Fault Logic
(bottom)
Three-Pole Open Logic
Three-pole open (3PO) logic is the top half of
Figure SECTION 5: .3. It is not affected by
enable setting ESOTF (see Settings Sheet 1 of 23 in Section 9: Setting the SEL-351P Recloser
Control).
The open circuit breaker condition is determined from the combination of:
• Circuit breaker status (52A)
• Load current condition (50L)
If the circuit breaker is open (52A = logical 0) and
current is below phase pickup 50LP
(50L = logical 0), then the three-pole open (3PO) condition is true:
3PO = logical 1 (circuit breaker open)
The 3POD dropout time qualifies circuit breaker closure, whether detected by circuit breaker
status (52A) or load current level (50L). When the circuit breaker is closed:
3PO = logical 0 (circuit breaker closed)