5.7.1 Triggering mechanism - general overview
Detection - state machine:
For most of the PQube 3 trigger events, the detection algorithm works with a state machine with
one (upper) or two (lower and upper) threshold value(s), along with a hysteresis value.
For voltage amplitude, current amplitude and analog input amplitude events, the detection
algorithm is based on comparison of “half-cycle” RMS amplitudes against the thresholds, referenced
as U
rms (1/2)
. The U
rms (1/2)
values are computed as an RMS value over a window of 1 cycle commencing
at the voltage signal zero crossing. The window slides by half a cycle for the next evaluation.
Complete definition of U
rms (1/2)
is described in IEC 61000-4-30 Ed3.
Events such as RVC (rapid voltage changes) and HF impulse have a more complex triggering condition
(RVC triggering method is described in IEC 61000-4-30 Ed3).
Hysteresis:
The detection (start of the event) occurs as soon as the parameter value crosses the threshold value
(low or high). The end of the event occurs when the threshold and the hysteresis is crossed. The goal
of a hysteresis is to avoid multiple (or bursts of) events when the parameter fluctuates around the
threshold value.
The example here shows the
use of hysteresis on a high
temperature detection with a
threshold of 22.5º C and a
hysteresis of 1º C.
Duration:
The duration of an event is the time difference between its start time and end time.
Events with no duration:
The following events, are not characterized with an end portion, and therefore have no duration
characteristic:
• Current events (phase current, neutral current, earth current)
• HF impulse events (they are characterized with more advanced parameters)
• Mechanical shocks and seismic disturbances
• Temperature/humidity events
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