iec arc flash sesign

[ukmike8]

NEC is very specific requiring arc flash mitigation no such mandatory
requirements in IEC standards. Any experience in IEC design methods.

 

[zappedagain]

If you are still looking for an answer to this you might try the power transmission and distribution forum - Forum 238.

Z

 

[ScottyUK]

Thought I had replied but seems like replies from Android devices aren't working at the moment.

There is no IEC 'standard', just the technical report IEC TR 61482. The report defines seven criteria which can be met, more-or-less independently of each other. It is upm to the specifier to decide which criteria matter.

The requirements for the testing method don't allow for insulating material to be damaged or displaced in order to place an ignition wire. The result of this clause is that judicious (or over-zealous) use of plastic materials allows a technical pass for equipment which would have zero chance of containing an arc in the event of one actually being struck. In my opinion this is one of the problems which occurs when manufacturers write the standards. I don't like the idea of something being internally arc classified by virtue of it being 'impossible' to strike an arc. 100 years ago it was impossible for the Titanic to sink, yet today it rests on the bed of the North Atlantic; need I say anything else about 'impossible'...?

You might want to check out Baldwin & Francis arc classified design of LV gear. Their design was influenced by an argumentative and difficult client, but the end result is a design which was tested - and passed - all seven criteria of IEC 61482 using an 80kA / 300ms arc. The board under test was built as an air-insulated board, yet the production model is manufactured as a fully insulated board. It's 'impossible' for an arc to be struck, but on the day that one does strike the people working on the gear have a very good chance of walking away from the event. Slight premium on some of the mass-market stuff but I know which I would rather be standing alongside if we ever have a Very Bad Day.

FWIW I don't work for B&F or have any financial interest in the company, but I have a reputation for being argumentative and difficult.

 

[ukmike8]

Thanks for the input.
Other than US it seems burn damage or death is largely ignored for LV manmade faults. Shell
are taking some retrofit and procedure changes in tankers. They are lucky because they have
always widely used fuses. Recent IEEE IAS article Mitigating Arc Flashes using IEC 61850
describes by installing SSRA relays at selected locations, which detects arc flash, then transfer
tripping using IEC 61850 GOOSE mitigates arc flash. Solution is to incorporate such methods in new designs.
ETAP is already on board using US IEEE methods.