CIRCUTOR QNA500 series - Manual (Page 32)

POWER QUALITY ANALYZER QNA500 8IO
QNA500 8IO Instruction manual 32 / 111
8.3.- POWER QUALITY
The voltage levels must be defined to calculate the power quality events.
• % Overvoltage threshold: Overvoltage detection depends on the value programmed in this
section. Any semi-cycle with an RMS value that exceeds this threshold (% over the nominal
voltage) will be understood as an overvoltage. The events file (EVQ) will save a record when
this value is exceeded, stating the phase, maximum voltage recorded, mean voltage, voltage
before the event occurred and the time during which this threshold has been exceeded.
• Overvoltage hysteresis: An overvoltage hysteresis will be defined so that the event start
voltage is not the same as the event end voltage. Therefore, an overvoltage starts when the
semi-cycle voltage exceeds the overvoltage threshold and ends when it goes below the said
threshold + the hysteresis programmed for this threshold.
• % Sag threshold: Sag detection depends on the value programmed in this section. Any semi-
cycle with an effective value that does not reach this threshold (% over the nominal voltage) will
be understood as a sag. The events file (EVQ) will save a record each time this value is not
exceeded, stating the minimum voltage recorded, mean voltage and the time during which this
threshold was not exceeded.
• Sag hysteresis: A sag hysteresis will be defined so that the sag start voltage is not the same
as the sag end voltage. Therefore, a sag is started when the voltage does not exceed the sag
threshold and it ends when this threshold is exceeded + the hysteresis programmed for this
threshold.
• % Interruption threshold: Interruption detection depends on the value programmed in this
section. Any semi-cycle with an effective value that does not reach this threshold (% over the
nominal voltage) will be understood as an interruption. The events file (EVQ) will save a record
each time this value is not exceeded, stating the minimum voltage recorded, mean voltage and
the time during which this threshold was not exceeded.
• Interruption hysteresis: An interruption hysteresis will be defined so that the interruption start
voltage is not the same as the interruption end voltage. Therefore, an interruption is started
when the voltage does not exceed the interruption threshold and it ends when this threshold is
exceeded + the hysteresis programmed for this threshold.
8.4.- TRANSIENTS
QNA500 can detect transients, according to different conditions. Transients can be detected in
accordance with 2 different conditions:
The following variables must be configured to record the transients:
1. Semi-cycle RMS value: RMS value of each cycle is calculated, updated each semi-cycle, and
compared with the maximum and minimum values programmed by the user. When the
maximum or minimum RMS value is exceeded, this is considered the moment when a transient
or disturbance is set off. We advise setting the maximum or minimum values far from the
nominal value existing in the installation. Otherwise, the analyzer will record many different
transients that will not be relevant in a future user analysis.