User manual

PQM-702, PQM-703 Operating Manual
48
Tab. 4. Summary of transient measurement modes in PQM-703.
Sampling frequency
Rise time with dV/dt method
Recording time range
(2000...20000 samples)
10 MHz
100 V/5 µs
0.2…2 ms
5 MHz
100 V/10 µs
0.4…4 ms
1 MHz
100 V/50 µs
2…20 ms
500 kHz
100 V/100 µs
4…40 ms
100 kHz
100 V/500 µs
20…200 ms
To configure the transients in PQM-703, a few options are provided for the user:
 main sampling frequency of A/D converter in the range from 100 kHz to 10 MHz,
 detection method: based on the set minimum transient amplitude (from 50 V to 5000 V) or
a minimum slew rate (dV/dt method),
 switching recording on/off of the transient waveforms,
 recording time for timeplot in the range from 2,000 to 20,000 samples,
 pretrigger time is within the range of 10% to 90% of the recording time.
The analyzer records the timeplot of transient only in channels where events meet the criteria
set by the user. After detecting a transient, the analyzer is insensitive to subsequent transients for
3 seconds. A special case is when the transient is detected only in one channel and in the time
between its detection and ending of the recording process, subsequent transients occur in other
channels. In this particular situation, the analyzer will record waveforms of all channels where tran-
sient events were detected. Since transients detected slightly later than the transient in the first
channel, will not have exactly the same pretrigger time (recording of these channels will end up at
the same time as the recording in the first channel triggered by the first event), "Sonel Analysis 2"
software marks these events as "Transient *". Waveforms for the channel that triggered the first
event, they will always appear with the other channels that triggered later event. Similarly, the open-
ing of the graph of a later waveform (secondary transient) will also display other channels, where
the disturbance occurred within the same time period. In this way, you can easily analyze the time
dependence between channels.
In the event table for transients the following parameters are specified:
 Extreme column includes maximum measured transient amplitude (peak-to-peak),
 Duration column presents an approximate duration of the disturbance.
Measuring lines are referenced to PE input (see also Fig. 26). Transient module monitors the
voltage between the inputs:
 L1-PE,
 L2-PE,
 L3-PE,
 N-PE.
3.10.1 Threshold method
Threshold method is chosen by selecting Threshold (in voltage settings of the measurement
point) and setting the threshold voltage in the range from 50 V to 5000 V. In this method, the ana-
lyzer detects a transient after it exceeds the pre-set amplitude in volts. Transients, whose amplitude
Note
For proper measurement of transients, it is necessary to connect PE input
of the analyzer to the local earthing system. It is also required for 3-wire
delta and wye systems without neutral conductor.