Schweitzer Engineering SEL-351P, Quick Start Manual

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Date Code 990430 Setting SEL
OGIC
®
Control Equations G-5
SEL-351P Manual Técnico
With a 52b contact connected, if the circuit breaker is open, the 52b contact is closed and input
IN101 is energized [IN101 = 1 (logical 1)]:
52A = !IN101 = NOT(IN101) = NOT(1) = 0
Thus, the SEL
OGIC
Control Equation circuit breaker status setting 52A sees an open circuit
breaker.
Example of NOT Operator ! Applied to Multiple Elements (within parentheses)
The SEL
OGIC
Control Equation trip unlatch setting is set as follows:
ULTR = !(51P1 + 51G1)
Refer also to Trip Logic in Section 5: Trip and Target Logic .
In this setting example, the unlatch condition comes true only when both the 51P1 (phase time-
overcurrent element pickup indication) and 51G1 (residual ground time-overcurrent element
pickup indication) Relay Word bits deassert:
ULTR = !(51P1 + 51G1) = NOT(51P1 + 51G1)
As stated previously, the logic within the parentheses is performed first. In this example, the
states of Relay Word bits 51P1 and 51G1 are ORed together. Then the NOT operator is applied
to the logic resultant from the parentheses.
If either one of 51P1 or 51G1 is still asserted [e.g., 51G1 = 1 (logical 1)], the unlatch condition is
not true:
ULTR = NOT(51P1 + 51G1) = NOT(0 + 1) = NOT(1) = 0
If both 51P1 and 51G1 are deasserted [i.e., 51P1 = 0 and 51G1 = 0 (logical 0)], the unlatch
condition is true:
ULTR = NOT(51P1 + 51G1) = NOT(0 + 0) = NOT(0) = 1
and the trip condition can unlatch, subject to other conditions in the trip logic (see Figure 5.1).
SEL
OGIC
Control Equation Rising Edge Operator /
The rising edge operator / is applied to individual Relay Word bits only – not to groups of
elements within parentheses. For example, the SEL
OGIC
Control Equation event report
generation setting uses rising edge operators:
ER = /51P1 + /51G1 + /OUT103