R.3.23
Date Code 20111215 Reference Manual SEL-421 Relay
SELOGIC Control Equation Programming
SELOGIC Control Equation Elements
In free-form programming, the relay evaluates the counter at execution of the
counter Input SEL
OGIC control equation (PCNnnIN or ACNnnIN). If you
enter an expression for the counter Reset (PCNnnR) or the counter Preset
(PCNnnPV), the values for Reset and Preset that the relay uses are the last
values the relay calculates before the input SEL
OGIC control equation
calculation. Because the relay uses the last values for Reset and Preset in this
manner, we recommend for most applications that you enter the Preset, Reset,
and Input statements together in the order shown in Example 3.9.
EXAMPLE 3.9 Counter Programming
The free-form programming equations that follow demonstrate how
to enter settings to control a protection counter in protection free-
form SEL
OGIC control equation programming. Programming for an
automation counter is similar.
Protection Counter 1 counts close operations of the circuit breaker
associated with the 52AA1 element. Initially, the current value,
PCN01CV, is zero. The relay increments the current value each time
the circuit breaker closes. The relay increases the count value,
PCN01CV, each time the circuit breaker closes and the element 52AA1
value changes from 0 to 1 (a rising edge). When the count reaches
1000, the timer automatically resets and begins counting again.
# Example protection counter programming
#
# This example counts how many times a three-pole circuit breaker closes
# The counter automatically resets every 1,000 operations
PCN01PV := 1000
PCN01R := PCN01Q
PCN01IN := 52AA1
The SELOGIC control equations below provide multiple-change
detection counting both close and open operations of the circuit
breaker. The intermediate value PSV01 turns on for one processing
interval each time the circuit breaker closes. The intermediate value
PSV02 turns on for one processing interval each time the circuit
Table 3.17 Counter Quantities
Type Quantity Name Range
Protection counters 32 PCN01–PCN32
Automation counters 32 ACN01–ACN32
Tabl e 3 . 18 Co unt er Pa ra m ete rs
Type Item Description Setting
Name
Examples
Input Input Value that the relay
counts
Boolean SELOGIC con-
trol equation setting
PCN01IN
ACN09IN
Input Preset Value Number of counts
before the output
turns on
Constant or expression
for the number of counts
PCN01PV
ACN09PV
Input Reset Counter reset Boolean SEL
OGIC con-
trol equation setting
PCN01R
ACN09R
Output Current Value Current accumu-
lated count
Value for math SEL
OGIC
control equations
PCN01CV
ACN09CV
Output Output Counter output Value for Boolean
SEL
OGIC control equa-
tions
PCN01Q
ACN09Q
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