So that the memory is filled only by data of important importance, the actual recording is activated only by a start signal (the so-called trigger signal). Each time the start signal becomes active, the data is recorded during the defined time and stored as a so-called event. So that the course of the signals can also be observed before and after the start time (trigger time), an event consists of three parts: the prehistory (recordings before the start time), the actual event and the post-history. The duration of the pre- and post-histories can be defined in the device.
As soon as the device has been parameterized and recording is started, the data is saved. This data is written to a memory that will be overwritten as soon as it is full. This overwriting of the ring buffer lasts until a signal starts the actual recording (triggering). Thus, the full history is available in memory at this time. The history gives an indication of anomalies in the network that could be responsible for the triggering of the trigger signal (motor starting current).
With the Power Visa the max. possible trigger setting 100 periods (max 30 periods pre and max 100 post). It is just 20 seconds, so for the analysis of a motor starting current completely unsuitable, because the starting process can take 1-2 minutes.
The Power Guide and Xplorer are capable of capturing 10000 periods (max 30 periods pre and max 9998 post), this equates to 3 minutes. Sufficient to analyze a startup process.
The duration of the recording of the actual event is determined by the trigger signal (trigger signal): As long as it is active, it is recorded. If the signal is very short, it is recorded for at least 80 microseconds, and if the signal is active for a very long time, the recording is aborted (post-trigger) after the maximum time (equal to the defined event time). The event itself is recorded for one period. The event duration is identical to the defined event time, regardless of the length of the trigger signal.
The post-history will reveal the consequences of a particular event.
The consequences can be as follows: vibrations (dynamics) in the system, voltage fluctuations or power interruptions.