Schweitzer Engineering Laboratories SEL-351 - Example of NOT Operator! Applied to Single Element; SEL OGIC Control Equation NOT Operator; SEL OGIC Control Equation Parentheses Operator

G-4 Setting SELOGIC
®
Control Equations Date Code 20001006
SEL-351 Instruction Manual
SELOGIC Control Equation Parentheses Operator ( )
More than one set of parentheses ( ) can be used in a SELOGIC Control Equation setting. For
example, the following SELOGIC Control Equation setting has two sets of parentheses:
SV7 = (SV7+IN1)*(50P1+50N1)
In the above example, the logic within the parentheses is processed first and then the two
parentheses resultants are ANDed together. The above example is from Figure 7.27 in Section 7:
Inputs, Outputs, Timers, and Other Control Logic. Parentheses cannot be “nested” (parentheses
within parentheses) in a SELOGIC Control Equation setting.
SELOGIC Control Equation NOT Operator !
The NOT operator ! is applied to a single Relay Word bit and also to multiple elements (within
parentheses). Following are examples of both.
Example of NOT Operator ! Applied to Single Element
The internal circuit breaker status logic in the SEL-351 Relay operates on 52a circuit breaker
auxiliary contact logic. The SELOGIC Control Equation circuit breaker status setting is labeled
52A. See Optoisolated Inputs in Section 7: Inputs, Outputs, Timers, and Other Control Logic
and Close Logic in Section 6: Close and Reclose Logic for more information on SELOGIC
Control Equation circuit breaker status setting 52A.
When a circuit breaker is closed, the 52a circuit breaker auxiliary contact is closed. When a
circuit breaker is open, the 52a contact is open.
The opposite is true for a 52b circuit breaker auxiliary contact. When a circuit breaker is closed,
the 52b circuit breaker auxiliary contact is open. When the circuit breaker is open, the 52b contact
is closed.
If a 52a contact is connected to optoisolated input IN1, the SELOGIC Control Equation circuit
breaker status setting 52A is set:
52A = IN1
Conversely, if a 52b contact is connected to optoisolated input IN1, the SELOGIC Control Equation
circuit breaker status setting 52A is set:
52A = !IN1 [=NOT(IN1)]
With a 52b contact connected, if the circuit breaker is closed, the 52b contact is open and input
IN1 is deenergized [IN1 = 0 (logical 0)]:
52A = !IN1 = NOT(IN1) = NOT(0) = 1
Thus, the SELOGIC Control Equation circuit breaker status setting 52A sees a closed circuit
breaker.
Courtesy of NationalSwitchgear.com