Use of MVA (k>1) vs Current (K=1) interrupting rating breakers

[rockman7892]

With MVA rated (K>1) being a thing of the past more associated with older Switchgear and new current rated (K=1) being available for new Switchgear or breaker replacements why would anyone want to purchase/install MVA rated breakers for new Switchgear or breaker replacement in older Switchgear?

the reason I ask is that I notice that many of the major manufacturers still offer MVA rated breakers along with the newer K=1 rated breakers. Even when replacing breakers in existing switchgear I believe you can still replace the older breakers with newer K=1 rated breakers in the existing switchgear.

Are there any specific reasons or applications that would justify the use of an MVA rated breaker?

 

[Pitt03]

After I posted this it just so happens that I was looking for a narrow frame MV vacuum breaker to replace and existing air break device and noticed that a particular manufacturer only offered this narrow frame breaker with an MVA (K>1) Total current rating.

Again this leaves me wondering why with the new vacuum technology would these MVA rated breakers still be offered as opposed to just the K=1 rated breakers. I thought the MVA rated breakers were a relic of air break devices that did not have the same interrupting capabilities that the vacuum breakers now have.

 

[dpc]

As long as the breaker has ratings that are suitable for your application, I would not be overly concerned about the test standard. Not sure why a "new" breaker would be rated on an MVA basis, but perhaps an offshoot of an older breaker that was originally tested under the older standard. Short circuit testing is expensive.