User manual

3 Design and measurement methods
51
K
K-Factor

U
t
Voltage transients

UR
1
, UR
2
Mains signalling

(1)
applies to U
N-PE
voltage
(2)
with C-5 clamps only
Detected events are recorded on a memory card as an entry containing:
 parameter type,
 channel, in which the event occurred,
 start and end time of the event,
 the threshold value set by the user,
 parameter extreme value measured during the event,
 parameter average value measured during the event.
Depending on the parameter type, you can set one, two or three thresholds which will be
checked by the analyzer. The table below lists all parameters for which the events can be detected,
including specification of threshold types.
Some of the parameters may have values that are positive or negative (+/-). For example: active
power, reactive power and power factor. Since the event detection threshold may only be a positive
value and to ensure proper detection for these parameters, the analyzer compares absolute values
of these parameters with the set threshold.
Two types of parameters: RMS voltage and RMS current may generate events, for which the
user may also record waveforms.
The analyzer records the waveforms of active channels (voltage and current) at the event start
and end. The user may set recording time for waveforms (from 100 ms to 1s) and the pretrigger
time (from 40 ms to 960 ms). Waveforms are saved in 8-bit format with sampling frequency of 10.24
kHz.
Information about the event is recorded when the event ends. In some cases, it may happen
that event is active when the recording is stopped (e.g. during a voltage dip). Information about such
event is also recorded, but with the following changes:
 there is no end-time of the event,
 extreme value is calculated only for the period until the recording is stopped,
 the average value is not reported,
 only the beginning waveform is available for RMS voltage or current related events.
To eliminate repeated event detection, when the value of the parameter oscillates around the
threshold value, the analyzer has a function of user-defined event detection hysteresis. It is defined
as a percentage value in the following manner:
 for RMS voltage events, it is the percent of the nominal voltage range (e.g. 2% of 230 V, which
is 4.6 V),
 for RMS current events, it is the percent of the nominal current range (e.g. for C-4 clamps and
in absence of current transducers, 2% hysteresis is 0.02×1000 A = 20 A,
Example
Threshold for detecting active power events was set at 10 kW. If the load
has a generator nature, the active power with correct connection of
clamps will be a negative value. If the measured absolute value exceeds
the threshold, i.e. 10 kW (e.g. -11 kW) an event will be recorded for ex-
ceeded maximum active power.