How much current can a 3 mm wire carry?

[Panthera Leo]

how much current can a 3 mm wire carry?

Hello

I was wondering how much current can a wire with of 3 mm diameter can carry?

Considering the maximum temperature of the wire doesn't change considerably, to melt the insulation...

Unfortunately I don't know which gauge wire this is...

Thanks

 

[Runei]

http://en.wikipedia.org/wiki/American_wire_gauge

3.264mm diameter is a gauge 8. From the table in the wiki article it looks like Gauge 8 can carry 472 Amperes for 10 seconds before fusing.

 

[Carl Pugh]

I pretty much agree with Runei using different data.
3 mm diameter is 0.118" dia
From book Reference Data for Radio Engineers
#9 AWG is 0.114" dia
Book gives fusing current of #9 AWG as 396 amp for copper.

 

[Panthera Leo]

highly appreciate your comments,

Considering this wire is used as the primary wire of a transformer, how many amps do you think it can carry for continuous duty? Because I didn't quite understand what you mean by "fusing current"... & how many kVA would you guess?

Is it the current which will fuse copper metals which have no insulation??!

 

[Windadct]

A completely different issue in a winding since the inner most winding - is "surrounded" by other winding, all of which are giving off heat. In this case the mechanical design, insulation thickness and type, as well as the transformers core heat - all play a role. This needs to be looked at from a total system perspective.
From the most basic analysis - if you can calculate the core losses and the winding ( restive) losses - estimating total watts, then calculate the temperature rise of the whole assembly ( Thermal resistance to the ambient- air etc) , this T rise needs to be well below the insulation rating (class) used on the wire. An then have some concern for hot spots - e.g. the temperature will not be uniform throughout the whole transformer - if this is for a one off or low volume build I would oversize the wire significantly - if for a school project, perhaps contact/visit a custom transformer shop and discuss - there is an art + skill + experience + technology to transformers.