ION7650 COMTRADE Time Stamps

[Nicholas_Brown]

Hi, I have a customer that utilizes COMTRADE waveform files for Sag/Swell Waveforms from our ION7650 metering.

They are seeing some behavior that they would like to get clarity on regarding the two Date/Time stamps that are reported in the .cfg Configuration file (the First Data Value, and the Trigger Point). 

In most cases, the .cfg file will have a First Data Value timestamp that is before the Trigger Point timestamp.  I believe this was their expected behaviour, as we are typically/always capturing pre-event cycles and should be getting some data points before the Trigger.  

However, they are also seeing that occasionally, the Trigger Point time is being represented as occuring before the First Data Value.  They are interpreting this as meaning that the Trigger of the waveform is occuring before the data is being captured.

They are curious to better understand these two Date/Time stamps and what they mean, and maybe some information on what conditions may dictate them happening in difference sequences.

Thanks for any help.

[Charles_Murison · Accepted solution]

Hello @Nicholas_Brown ,

The description of time of first point and time of trigger is true under most conditions. The time of trigger is when the pulse was received by the waveform recorder module. The time of first point is the time stamp of the first sample inside the record.

There is a way for meter with pre-event cycles to still have a trigger time before the first sample time. If a meter is currently recording a waveform and a second pulse is received by the waveform recorder, the meter will finish the current record a then start a new record as soon as the first recording finished. When this happens the second waveform has a trigger time before the start of the first point in the second record.

Regards,

Charles

[Nicholas_Brown]

That makes complete sense, thank you @Charles_Murison