SCCR Ratings - Applicability

[Charz]

Is SCCR applicable for MV Switchgear, LV Switchgear or only for Industrial control panels only?

As I read about the SCCR, it says

• The SCCR for the control panel is determined the lowest SCCR value for any component or branch circuit.

See below snapshot from the web,


It means that any miniature circuit breaker in the LV Switchgear/ MV Switchgear will not have high short circuit rating for it, therefore the MV/LV Switchgear cannot have the high SCCR.

Can some one put more light on this!

 

[petersonra]

It means that any miniature circuit breaker in the LV Switchgear/ MV Switchgear will not have high short circuit rating for it, therefore the MV/LV Switchgear cannot have the high SCCR.

Can some one put more light on this!

It is unlikely a miniature CB would be used in a power circuit in any kind of switchgear. Control circuits do not require a SCCR in industrial control panels, and likely it is the same way in switchgear.

 

[Jraef]

In MV gear and LV switchboards, switchgear and panelboards there are other ratings that cover the same issues as SCCR. But the issues don’t mix between MV and LV in the same equipment. If you have a separate LV power feed to MV equipment that is, for example powering air conditioning equipment or a UPS, there would need to be an SCCR rating of that LV system, but based on the Available Fault Current of whatever LV source is providing that power. So for example if the MV gear has a small 15kVA 208/120V station service transformer, the AFC will be based on that transformer secondary, not the MV gear rating ahead of it.