Sel SEL-421 - Sequencing Timer Quantities; Sequencing Timer Parameters; Sequencing Timer Timing Diagram

R.3.21
Date Code 20111215 Reference Manual SEL-421 Relay
SELOGIC Control Equation Programming
SELOGIC Control Equation Elements
A sequencing timer counts time by incrementing the Elapsed Time when
SEL
OGIC control equation execution reaches the Input equation if the Reset is
off and the Input is on. The Output turns on when the Elapsed Time reaches or
exceeds the Preset Time. Whenever the Reset is on, the relay sets the Output
to zero, then clears the Elapsed Time, and stops accumulating time (even if
Input is on).
Figure 3.8 is a timing diagram for typical sequencing timer operation.
Figure 3.8 Sequencing Timer Timing Diagram
Table 3.15 Sequencing Timer Quantities
Type Quantity Name Range
Protection free-form sequencing timers 32 PST01–PST32
Automation free-form sequencing timers 32 AST01–AST32
Table 3.16 Sequencing Timer Parameters
Type Item Description Setting
Name
Examples
Input Input Value that the
relay times
Boolean SELOGIC con-
trol equation setting
PST01IN
AST07IN
Input Preset Time Time the input
must be on before
the output turns
on
Time value. Protection
uses cycles, while auto-
mation uses seconds.
PST01PT
AST07PT
Input Reset Timer reset Boolean SEL
OGIC con-
trol equation setting
PST01R
AST07R
Output Elapsed Time Time accumulated
since the last reset
Value for math SEL
OGIC
control equations. Pro-
tection uses cycles, while
automation uses seconds.
PST01ET
AST07ET
Output Output Timer output Value for Boolean
SEL
OGIC control equa-
tions
PST01Q
AST07Q
Elapsed Time
Increases While
Input Is On
Elapsed Time
Does Not Reset
When Input Is Off
Elapsed Time Reaches
Preset Value
Elapsed Time
PST01ET
Input
PST01IN
Reset
PST01R
Output
PST01Q
Preset Value
PST01PT