How is I1max defined?

[Jack Ryan]

Logically, I1max, being the maximum rated input current, would include inrush current.

I can't find an official definition that would confirm that.

Can anyone give me the official definition and let me know where it is defined for future reference?

(Sorry if this is the wrong place to post this. I didn't see an electrical section).

Thanks

Jack

 

[skotl]

I'm a bit confused - apologies - what's the context? Is it that you're trying to size a supply to a welder based on its inrush current?

If so, and on the assumption you're using MCBs (or the equivalent in Oz) then it depends on the curve of the breaker (B-curve, C-curve etc).

There's an easy explanation here: https://www.electricalclassroom.com/b-c-d-k-and-z-mcb-trip-curves/

So, as it says, a B curve will withstand a peak current of 3-5 times its rated current, and a C curve will withstand a peak current of 5-10 times. That means that a C32 breaker (with a suitably rated cable and connectors) will not trip with a very brief / inrush current of at least 150A.

 

[Jack Ryan]

I'm a bit confused - apologies - what's the context? Is it that you're trying to size a supply to a welder based on its inrush current?

Sorry for my lack of clarity.

I refer to the rating plate on a welder where a value of I1max is specified. This is the maximum rated input (mains) current. I would like to know exactly how that value is officially defined. How it is officially determined would help.

Thanks
Jack

 

[skotl]

Ah ok. I'd be surprised if there was a single global "official" definition, given the huge number of manufacturers.

That said I can't see why I1max would be any different to what it says on the tin - "Maximum inrush amps" aka highest current the device is expected to consume under any normal circumstance (so any current consumption above this would likely constitute a short circuit)

 

[Jack Ryan]

Ah ok. I'd be surprised if there was a single global "official" definition, given the huge number of manufacturers.

That said I can't see why I1max would be any different to what it says on the tin - "Maximum inrush amps" aka highest current the device is expected to consume under any normal circumstance (so any current consumption above this would likely constitute a short circuit)

Thanks for that.

It is a standard to which the manufacturers must adhere when making the plate and yes, I would assume in includes inrush current. I would, nevertheless, like to see the standard and confirm that.

I1eff, also listed on the plate, is used to determine the ampacity of the wiring and breaker that supplies the device. I1max shows the headroom required of the mains supply - particularly important for determining generator supplies.

However, I am curious and I just like to know. The definition must be listed in one of the electrical standards.

Jack

 

[skotl]

Yeah, but which electrical standard? Oz will be different to UK, which will be different to US, EU etc.
And these electrical standards are normally for wiring / supply, whereas trading standards would be more likely to cover manufactured goods.

Finally, you have manufacturers who don't care and slap any old plate on

 

[Kram]

Theres an ISO standard, very £££ if you want to see the text of the standard!

 

[Jack Ryan]

Yeah, but which electrical standard? Oz will be different to UK, which will be different to US, EU etc.
And these electrical standards are normally for wiring / supply, whereas trading standards would be more likely to cover manufactured goods.

Yes, they might differ but not by much. Even the compliance plate has been standardised so that they are now almost identical in the UK (and probably EU), US and Australia/NZ.

Finally, you have manufacturers who don't care and slap any old plate on

If an item is officially sold here, it must comply with Australian standards. If you personally import something from elsewhere, you are on your own.

Jack

 

[Jack Ryan]

Theres an ISO standard, very £££ if you want to see the text of the standard!

There are a lot of ISO standards. The question is, which one? I have several, not the correct several.

Jack

 

[carbon]

Is this specific to welders? As I’ve not seen it on the machines that I sell with motors fitted. Or on machines that I’ve repaired from other manufacturers

 

[Turbo]

All you need to provide correct electricity supply is the Imax figure & voltage. Irrespective of who makes a welder Imax is the maximum current the welder will draw from your supply so if you rate your wiring & breakers accordingly you shouldn't have a problem.

 

[Jack Ryan]

Is this specific to welders? As I’ve not seen it on the machines that I sell with motors fitted. Or on machines that I’ve repaired from other manufacturers

It applies to welding machines than connect to mains (grid) power.
Jack

 

[Jack Ryan]

All you need to provide correct electricity supply is the Imax figure & voltage. Irrespective of who makes a welder Imax is the maximum current the welder will draw from your supply so if you rate your wiring & breakers accordingly you shouldn't have a problem.

That is not quite right.

Ampacity is derived from I1eff, not I1max and that determines the required breaker and cable.

Jack

 

[Jack Ryan]

I am a step closer. I found this in a BOC catalogue:

BOC welding machines are designed and manufactured to conform to IEC 60974 or AS 60974. This Standard not only covers the machine but also the input cable and plug requirements including the size of the plug that should be used.

I believe that AS 60974.1 is what is needed. It would be nice to know before spending the dollars though.

Jack

 

[Jack Ryan]

More BOC information about regulatory compliance. Ignore the I1eff highlighting, it is part of the document.

Note that the regulatory compliance mark and number are printed on the compliance plate.

Jack

 

[Jack Ryan]

I found the equivalent British standard and it's a bit of a let-down:

Which is what I said in the beginning. I guess I'll just have to assume it includes inrush current.

Thanks for pushing me along guys. I had already searched for the Australian standard but it was hidden behind a paywall (as is usual). Someone had posted a licensed copy of the British standard. It's OK though, I only peaked.

Jack

 

[Jack Ryan]

Easiest (and possibly best) solution is to actually ask the supplier/manufacturer. Internet fora may provide incorrect replies - for several reasons.

Possibly, the manufacturer would certainly know but it would be a matter of reaching the people concerned. Suppliers probably wouldn't know - even with BOC, as I understand it, the tests are done by an independent lab.

You are right, the "Internet" is not always correct but I was after a standard and that should be pretty safe.

I'll ask BOC because if I can find how the test is performed, I'll have my answer.

Jack

 

[Robotstar5]

It may be worth contacting the tech dept at TWI

 

[mtt.tr]

No it won't include inrush current, it's maximum current it will draw in normal operation.

Inrush will be dealt with breaker type b, c, d,.

You won't get an inrush current as it's variable.

The effective is the RMS value I believe

 

[Jack Ryan]

It may be worth contacting the tech dept at TWI

Hadn't thought of that - thanks

Jack