SATEC EM920 Operation Manual - Manual (Page 113)

Chapter 5 Configuring the EM920
Configuring Recorders
EM920 Power Quality and Revenue Meter 113
Configuring the Waveform Recorder
The EM920 can store waveforms in three log files.
Configurable waveform log files #1 and #2 can record
waveforms at four programmable sampling rates: 32, 64,
128 or 256 samples per cycle. A log file stores up to 7
channels simultaneously (three voltage channels and four
current channels) with a programmable length and up to 20
pre-event cycles.
Waveform log file #3 is pre-configured for fast transient
recording. It is only operational in presence of the optional
transient module and stores 1-cycle transient waveforms
sampled at a rate of 1024 samples per cycle. If you do not
use a transient module, you can remove this file to free more
memory for other files.
The waveform record length depends on a recording option
you can select for each configurable waveform file:
• Fixed recording time: a triggered waveform is recorded
up to the maximum specified length. Other events that
may be triggered before the recording ends may not
be recorded completely if they extend beyond the
recording time.
•
Event-controlled recording time: a waveform will
extend for as long as trigger conditions exist plus a
user-defined post-event time of up to 2048 cycles
(possibly extended to complete a file record). The
maximum length for an active trigger is limited to
avoid continuous triggering. The minimum record
length can be extended by post-event time if needed.
NOTE
In event-controlled mode, waveform triggering on end of a
PQ or fault event, or by a pulsed event (like a voltage
transient or timer-triggered events), which have no
duration, can only record minimum-length waveforms that
may be extended by a user-defined pre-event and post-
event time.
The minimum waveform length that can be recorded is 512
samples of the input signal, or 0.5 to 16 cycles depending on
the selected sampling rate. It is the size of physical records
the waveform recorder uses to store waveforms to files.
Whenever a waveform ends before the last file record is
completed, it extends up to the file record size.
If a file is configured to store more samples per event than a
single file record can hold, the recorder stores as many
records as required for recording the entire event. The file
records in a series are identified by the same series number,
so they may be easily linked and plotted together.
To configure a waveform log file:
1. Double click on a waveform log partition with the left
mouse button.