- Thread starter rusty69bus
- Start date
Drains
Yeah, nah.
- Messages
- 7,718
- Location
- Sefton, South Island, NZ
I may be wrong... but arn't those rubbish duty cycles? Like, for a 200A welder, the 200A doesn't even rate in the published duty cycle. I don't get it, is this typical for a diy market welder?
How would a prospective buyer make an assessment of the machine based on these figures? Other than the offered test of course...
rusty69bus
moving to the goldcoast
- Messages
- 2,704
- Location
- limbo
sounds great i'll bring the test piece, my vw camper van, who's bringing the bbq and beer
rusty69bus
moving to the goldcoast
- Messages
- 2,704
- Location
- limbo
Duty Cycle
Arc welders are commonly rated on a duty cycle basis.
For example a machine might be rated as follows:
400A maximum at 35% duty
300A at 60% duty
230A at 100% duty
In line with European Standard, duty cycle is measured over a repetitive 10-minute period
(EN60974-1).
So, in this example, 400A at 35% duty means the welding output can be maintained at 400A for
3.5 minutes out of each 10-minute period (also see Point 5, right). For the remaining 6.5 minutes the machine must be left to cool/idle.
Equally 7 welds of 0.5 minutes duration each at 400A, totalling 3.5 minutes over a 10 minute period, is still 35% duty cycle, irrespective of the
time between each weld.
Outputs are to be quoted at a number of duty cycles, as the duty cycle increases the permitted output current decreases.
100% duty means continuous.
For most machines, the current output capability at other duty cycles, can be estimated by the following worked examples:
Machine ‘A’ has a known duty capability of
250A at 35%; what duty is possible at 200A?
Answer = (250/200)2 x 35% = 55%
Machine "B" has a known duty capability of
500A at 20%; what duty is possible at 350A?
Answer = (500/350)2 x 20% =41%
lnverter based designs have other limitations and this type of calculation may not give accurate results. Another, sometimes useful approach, is to work as follows:
Here the current is 400A and the known duty
is 40%.
Therefore the ‘heating effect’ of the current (or
R.M.S. value)
=√ (40% of (400)2)
=√ (40/100 x 160,000)
=√ 64,000
=252A
So 400A at 40% duty as shown above has the
same "heating effect" in the machine as 252A
output continuously (100% duty).
Things to Remember about Duty Cycle:
1. 100% duty means continuous
2. Duty cycle is measured over 10-minute periods (EN60974-1). Ratings based on 5-minute cycles are generally higher!
3. Most manual welding achieves low actual duty cycles: e.g. MMA = 10% average max MIG = 40% average max
4. Machines, specified as per EN60974-1, can achieve their ratings at up to 400°C ambient. Normal UK ambients rarely exceed 250°C so there are generally good margins.
5. From cold (20°C) a machine can normally provide full output for a long period of time before its internal temperatures come even close to maximum. It usually takes 2-3 hrs at full output to bring a 500A machine "to temperature”. Clearly the smaller the machine the quicker it heats up but, from cold, a machine can normally exceed its quoted duty cycle for some time.
6. There could be problems other than thermal trips if you choose a "light duty" machine to do a ”heavy duty" task, even if the current and duty cycle is well within specification. consideration must be given to the mechanical limitations in the system, feed mechanisms, general ruggedness etc. “Light duty” does not apply just to current range and duty cycle capability. “Cost engineered” is just what it means!
found this here http://www.cromwell.co.uk/static/publication/165-old/pages/1561.pdf hope it helps the rest of us understand
I think it would be a great idea for Tachi or Paul to try a few machines out and give us our own little review from guys who are at it daily and know what a welder shoud be doing. If someone were buying a machine it could be sent to our two welders and then we could all contribute for the cost of postage to the actual buyer after the test as we (the group) are getting a review.
Alex
Alex
Country Joe
Argoshield Dark
- Messages
- 1,743
- Location
- Somerset - United Kingdom
I noticed that yesterday, and it's left me really wanting to know what was originally said.
I guess I should have been quicker!
Was it something quite rude then, Lexi?
Last edited:
Country Joe
Argoshield Dark
- Messages
- 1,743
- Location
- Somerset - United Kingdom
Oh no! Now I've made you put it back on! Shoulda suggested you PM'd it!
Feels like I'm putting us in trouble here!
Anyway, thanks Lexi, it was niggling at me - seemed like I really had to know!
Cheers,
CJ
Feels like I'm putting us in trouble here!
Anyway, thanks Lexi, it was niggling at me - seemed like I really had to know!
Cheers,
CJ
Drains
Yeah, nah.
- Messages
- 7,718
- Location
- Sefton, South Island, NZ
There is subtle but arguably useful or necessary use of swearwords on Radio 4. Swearing is not permitted on Radio 1.
UKWelder doesn't permit swearing.
The defense rests.
(TechnicAl and other regulars on UKWelder, don't hit me!!)
Si
UKWelder doesn't permit swearing.
The defense rests.
(TechnicAl and other regulars on UKWelder, don't hit me!!)
Si
- Messages
- 13,521
- Location
- England
That little alteration was down to me.
I'm no stranger to swearing, but one of Malcolm's wishes is for the forum to stay 'Family Friendly' as most of you will know.
So in my interpretaion of that, it means no swearing.
I notice you have reposted it, rather than remove i have *** it this time.
Thanks people.
I'm no stranger to swearing, but one of Malcolm's wishes is for the forum to stay 'Family Friendly' as most of you will know.
So in my interpretaion of that, it means no swearing.
I notice you have reposted it, rather than remove i have *** it this time.
Thanks people.
Ha Ha ...........All have sinned....none of us are worthy........I like funny endings.
Alex
Tim
De-cloaked
- Messages
- 64
You can have a go on my 181 if your ever in Wiltshire...
...but only if you show me how to use it properly PM me if you are coming this way and do want to give it a go...
DIY Welding
Member
- Messages
- 298
Cant understand whats weldequips problem I got the specs from SWP on there lit we did not have one in stock we normally stock them we have tested them and they are a nice bit of kit, if the manufactor has got the specs wrong on there lit then I will change it, why Weldequip is intersted what I have on my website is strange to me
You were having a pop at Portamig so I was having a pop back! The Classic MIGs are fine machines, & I sold shed loads over the years (under the Eland badge), so if you have any questions DIY do drop me a line!
Those duty cycle figures were way off the mark, so somebody has cocked up big time. I was just bringing the fact to your attention before Trading Standards might.
weldequip
DIY Welding
Member
- Messages
- 298
I would supply the following for a best buy test,
1, Hypertherm powermax 30 single phase plasma cutter, ideal for the home market, cuts 12mm 3 year warranty
2, Butters AC/DC 160 Tig welder single phase 13A our biggest selling tig set welds up to 4mm Ali
3, Butters 181 mig set single phase 13A
Also who ever does the test we will supply a Parweld helmet FREE for there trouble
1, Hypertherm powermax 30 single phase plasma cutter, ideal for the home market, cuts 12mm 3 year warranty
2, Butters AC/DC 160 Tig welder single phase 13A our biggest selling tig set welds up to 4mm Ali
3, Butters 181 mig set single phase 13A
Also who ever does the test we will supply a Parweld helmet FREE for there trouble
