62
Voltage & Current Waveforms
Introduction
Waveforms are very different from logs and other graphs. A waveform is the most basic direct
measurement. It displays the instantaneous levels of voltage and current as they continually vary, as
you see on an oscilloscope. All other measurements are derived from them. Even the RMS
measurements of voltage and current are derived from these basic samples. Logs, on the other hand
plot measurements that are derived from the basic sampling. They generally have no relation to what
is occurring at a specific instant of time. So although both waveforms and logs are presented
graphically, they are not the same and are not treated the same in analysis. If you could zoom into a
data log of Vrms, you might be able to zoom in further and further until you arrive at the measurement
of Vrms representing 1/2 cycle of voltage. However, you would not eventually see a waveform of
voltage.
Saving Consumption Waveforms
ATPOL II allows you to store sets of waveforms whenever you wish to. These waveforms may be
uploaded and displayed on your PC at any time. Consumption waveforms are captured by the action of
the user. Triggered waveforms are automatically captured due to some characteristic of the waveform.
Triggered waveforms are discussed in later sections.
Whenever a set of consumption waveforms is manually recorded by ATPOL II, all 3 voltages and all
four 4 currents are recorded for 50 milliseconds. This time-coincident snapshot of 7 waveforms is
called a "waveform set". Please Note: When operating in one of the 400 Hz operating modes the
waveforms are recorded for 7 msec to give sufficient resolution to these much faster frequencies.
You can capture a waveform set at anytime, either using the keypad of ATPOL II or PSM if ATPOL II is
connected. To save a waveform set in ATPOL II
without using PSM, press the “Wave” key at the lower
right of the keypad. The number that is assigned to the waveform set is then shown on the display.
The waveform data storage space within ATPOL II is separate from the space reserved for other types
of data. Therefore it does not limit the size of your logs or write over any other type of data. Whenever
you store a waveform set in ATPOL II it writes over the oldest waveform set that is stored in the meter.
One of the wavesets, waveset1, is a special waveset. It is automatically captured by ATPOL II when
you initiate monitoring. The benefit of doing this is you can always retrieve a look at what the
waveforms were like when monitoring began.
It must be noted that the ATPOL II allows the user to disable waveform sets. In this case, you will be
unable to save wavesets. The ability to enable or disable the saving of consumption waveforms is
discussed in the
Allocating Memory within ATPOL II
To use PSM to capture a waveform set and have it stored in the
connected ATPOL II
meter, click on “Remote Control” at the main
menu and then click on the “Wave” key of the representation of
the ATPOL II keyboard on the screen.
Содержание ATPOL II
Страница 109: ...109...