Sag / Swell ?? / Transient ??? / What do you think?

[Anonymous user]

Hello

I do not speak English well.

I have a question for you.

I think Sag / Swell.

Why Transient ??

Module has not changed

Thanks!

[jbickel]

Based on the image you have provided and the definition provided by recognized PQ standards, it is a voltage sag event. A good rule of thumb is that transients are one cycle or less. In this case, the term "transient" is misleading.

[DanL]

Assuming this is from an ION meter, the "transient" terms are comming from the ION Transient Module. Either the querry filter (ALARM2.jpg) is hiding the Sag events generated by the SagSwell module, or perhaps the SagSwell module is mis-configured. As far as I know the default configuration of ION templates with a transient module is to disable the transient module during sag/swell events. Also possible is that the transient module's waveshape comparing algorithm detected the leading edge of the disturbance before the RMS level fell below the sag/swell module's threshold.

[jbickel]

The device is providing Disturbance Direction Detection information for this particular event. I know the old PowerLogic devices (CM4000/CM3350) only provided DDD information for events classified as sags or swells (for various reasons that are not pertinent to this discussion). Out of curiosity, does the ION device provide DDD information for events classified as transient events?

But back to the original question...the textbook definition of this event is that it's a voltage sag.

[DanL]

The DDD module source inputs are expected to be from at least the sag/swell module and optionally the transient module ("transient" detection and measurement on the ION module differs dramatically from the CM4000T transient feature). For example the ION7550 and PM8000 support SagSwell and DDD, but not transients.

The SagSwell module, transient module, and DDD modules operate independantly unless configured otherwise by linking enable/disable logic in the template. It looks like the DDD module allows any input trigger to start the capture and evaluation of waveform data to compute the direction and confidence.

Yes I agree the waveform depicts a classical voltage sag, but the event log indicates the event was detected (at least) by the transient module. Sorry about the confusion.

Dan

[Anonymous user]

Thank you.

Sowhydidthis phenomenonappear?

[jbickel]

Dan - Would like to talk to you offline sometime about some of the potential issues of performing DDD on transients (at your discretion).

[jbickel · Accepted solution]

Now that is the magic question...

Based on the information provided, all that can authoritatively be said is that it's a single-phase event lasting approximately 5 cycles. Determining the actual cause of the event would require a lot more data and contextual information.