Operation Techniques 91
4.17.7 Setpoint Programming Techniques
This section describes setpoint programming practice in examples. It is
recommended to use a special form provided in Appendix C to plan setpoint
parameters prior the user changes them in the instrument. Refer to Appendix B
(Tables B-6, B-7) for the entire list of available setpoint triggers and their
abbreviations.
Using Numeric Triggers with Hysteresis
Example 4-1 illustrates a simple usage of numeric triggers.
Suppose that the setpoint monitors high current over 1500 A, and a low power
factor, either lag or lead, under 0.85, on either phase. All conditions are combined
by OR operation. This means that when either value exceeds its predefined operate
limit, the setpoint is triggered, and a 3-second delay timer runs. If the measured
value remains away from the threshold for minimum of 3 seconds, the setpoint is
operated. Three actions are made on setpoint operation:
- relay #1 is activated (assume, to operate alarm)
- counter #2 is incremented to count the number of relay operations
- setpoint operation and two actions mentioned above are recorded in the event
log
Example 4-1 Sample Of Using Numeric Triggers With Hysteresis
Trigger Conditions
Conjunction Trigger parameter Condi-
tion
Operateli
mit
Releaseli
mit
Condition #1 OR High current
≥
1500 1450
Condition #2 OR Low PF Lag
≤
0.85 0.90
Condition #3 OR Low PF Lead
≤
0.85 0.90
Condition #4 OR None
Setpoint actions Delays
Action type Action target Unit Operate Release
Action #1 Operate relay #1 1 s 3 5
Action #2 INC counter #2
Action #3 Event logging Operate
Action #4 None
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