Hello all,

In IEEE 1584, the arcing current and the reduced arcing current are calculated from the bolted short-circuit current to take into account the arc impedance.
This method is relevant when the different sources supplying the short-circuit are voltage sources.

But what about when the one or one of the sources feeding the short-circuit is a power station unit with full size converter (for instance large UPS or PV or wind power station unit with full converter)?
In this case, for the calculation of the short-circuit current (see IEC 60909-0_2016), the source is modeled in positive-sequence system by a current source. The value of the short-circuit current is therefore independent of the downstream impedance, in particular of the arc impedance.

My question is then the following: is it relevant to use the IEEE 1584 method when one of the sources feeding the short-circuit is a power station unit with full size converter?

Thank you for your contributions on this topic.
Best regards

Philippe Aupetit
Trace software International

Great question! Looking at the scope of IEEE 1584, it is the model for calculating incident energy, arcing current, and working distance - very limited. The question is often raised: How do you model this source, that source, etc. We always came back to: you provide a bolted short circuit current and other variables and that's it. How you derive those values is not addressed within IEEE 1584.

I co-authored an IEEE paper several years ago comparing ANSI and IEC short circuit calculation methods and how it might affect IEEE 1584 results. Although most results tracked closely, as you might expect if the calculated arcing current was close to a transition from instantaneous to time delay, different methods could have an impact on the arc duration and incident energy.

So, IEEE 1584 is the model for incident energy etc. but it does does not address methods for determining the bolted fault current or clearing time.

Hope that helps clarify!

Thanks Jim for your response, your opinions and comments are always valuable.

Unfortunately, I do not know enough about the ANSI standard to appreciate precisely the differences in the calculation of short-circuit currents with the IEC standard.

But, notwithstanding the standard for calculating short-circuit currents, my question is that if the source feeding the short-circuit is a current source (for example power station unit with full size converter), I would tend to think that the arcing current should be taken equal to the bolted short-circuit current as the short-circuit current is then independent of the arc impedance.
But what, in that case , of the reduced arcing current ?

Philippe Aupetit
Trace software International

Got it!

As far as the current, that makes sense. But if the current remains constant and there is arc impedance, that would result in a larger arcing voltage and I'm not sure how that is reflected in the model. I believe you hit upon one of the areas that was not addressed in IEEE 1584.

btw, this is just an informal opinion and may or may not not represent the views of IEEE.

Thank you Jim for your opinion which matches mine .
This point could perhaps be taken into account in a future version of IEEE 1584 ......
Best regards