Satec expertmeter EM720 Operation Manual page 90

Chapter 5 Configuring the EM720
Using Numeric Triggers
Using Binary Triggers
Using Event Flags
Using Interval Timers
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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 always specified in primary units.
If you use relational operators as "<=" (under or equal) or
">=" (over or equal), always specify a correct Release Limit
for the trigger. If you do not want to use hysteresis, set the
Release Limit to the same as the Operate Limit.
Binary (digital) triggers, as 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
internal static events generated by device diagnostics, and by
the Power Quality and Fault recorders.
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
examples of pulsed events are pulse inputs (transition pulses
on the digital inputs), internal pulsed events (energy pulses
and time interval pulses), and events generated by the
interval timers. The logical controller automatically clears
pulsed events at the end of each scan, so that triggers that
used pulsed events are prevented from being triggered by
the same event once again.
The EM720 has 8 common binary flags, called event flags,
which can be individually set, cleared and tested through
setpoints or remotely.
Event flags can be used in different applications, for example,
to transfer events between setpoints in order to expand a
logical expression or a list of actions that have to be done for
a specific event, or to remotely trigger setpoint actions from
the SCADA system or from a PLC. See
how to check and change event flags via PAS.
The EM720 has 4 interval timers that are commonly used for
periodic recording of interval data at the time of the fault or
in the presence of other events detected by setpoints. They
can be programmed to generate periodic events at user-
defined intervals (see
Interval timers are not synchronized with the clock. When
you run a timer, it generates a pulsed timer event that can
trigger a setpoint if you have put the timer into a list of the
EM720 Power Quality and Revenue Meter
General Meter Setup
Device Event Flags
Using Periodic Timers).
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