SATEC PM174 Manual - Manual (Page 82)

Chapter 4 PAS Application General Meter Setup
82 Series PM174 Powermeters
Option Range Description
Release limit
The threshold (in primary units) at which the
conditional expression would be evaluated to false.
Defines the hysteresis for analog triggers. Not
applicable for digital triggers.
Actions
Action See Appendix C The action performed when the setpoint expression is
evaluated to true (the setpoint is in operated state)
Delays
Operate delay 0.1-999.9 sec The time delay before operation when the operate
conditions are fulfilled
Release delay 0.1-999.9 sec The time delay before release when the release
conditions are fulfilled
Setpoint #1 is factory preset to provide standard periodic data
logs on a 15-minute time basis. It is linked to the device clock
and runs data logs #1 and #2 at 15-minute boundaries of an
hour.
Using Logical Expressions
Logical operators OR/AND are treated in a simplified manner.
They have no specific priority or precedence rules.
Any trigger condition bound to the logical expression by the
OR operator and evaluated as “true” will override any
preceding condition evaluated as “false”. Similarly, any trigger
condition evaluated as “false” and bound by the AND operator
will override any condition evaluated before it as “true”.
To avoid confusion, it is recommended not to alternate
different logical operators in one expression. Instead, bring all
conditions that use the same logical operator together at one
side of the expression, and the others - at the opposite side.
To explicitly override all other conditions with the critical
trigger, put it at the end of the expression using the OR
operator if you want the setpoint to be operated anyway when
the trigger condition is asserted, and with the AND operator, if
the setpoint should not be operated while the critical trigger is
not asserted.
Using Numeric Triggers
For numeric (analog) triggers, a setpoint allows you to specify
two thresholds for each trigger to provide hysteresis (dead
band) for setpoint operations. The Operate Limit defines the
operating threshold, and the second Release Limit defines the
release threshold for the trigger. The trigger thresholds are
specified in primary units.
If you do not want to use hysteresis for the trigger, set the
Release Limit to the same as the Operate Limit.
Using Binary Triggers
Binary (digital) triggers, like digital inputs, relays, or internal
static and pulsed events, are tested for ON (closed/set) or
OFF (open/cleared) status.
The binary events are divided into two types: static events and
pulsed events. Static events are level-sensitive events. A
static event is asserted all the time while the corresponding
condition exists. Examples are digital inputs, relays and event
flags.
Pulsed events are edge-sensitive events with auto-reset. A
pulsed event is generated for a trigger only once when a
positive transition edge is detected on the trigger input. The