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Duty Cycle



WookieWelding
03-09-2011, 10:05 PM
Does longevity use the USA standard or the EURO standard for Calculating Duty Cycle ?

180guy
03-09-2011, 11:39 PM
Good question.

SICFabrications
03-09-2011, 11:59 PM
not sure.... i just weld till it starts to smell funny, then let it cool for a few seconds..... ha!

tigqk
03-10-2011, 12:49 AM
Don't understand the question?...duty cycle is a percentage whether you use an hour or ten minutes it will be the same number.Think about how you would do it if you had a 140 amp mig or econotig where you knew it would not be able to perform for the hour you'd specify over ten minutes because it is the only way to measure it. I have had a look at the Longevity welder I have and it is made to heavy in some places like the tig cord wrap, it isn't goin to wear out from abrasion, inside heavy copper conductors, hand soldering on components most would only wave solder, telecom grade mosfets, dbl pole dbl throw switches, and something alot of us love to hate because it is so large the cooling fan.Enormous cooling fan to be exact.
Here is an article I found;


"Welders duty cycle rating (Specification) is an assigned figure of merit for sustainability of output current. It is expressed as a percentage of weld time over a 10 minute period (where 100% Weld On time equals 10 minutes) at a given output current. For example, let's consider the specification: 300A @ 40% duty cycle. A 40% duty cycle represents 4 minutes out of a 10 minute period that the Welder can operate. For the other 6 minutes, the Welder must be allowed to cool down. If not, the Welder will shut down and light an over temperature LED, or display a Thermal Error code. If this occurs the Weldor (a person who Welds Metal) has to stop production and wait for the Over temperature condition to clear. The more basic Welders (Transformer/ SCR based Welders) usually incorporate two bi-metallic strip type Thermostats (one on the Input Rectifier Heatsink Assembly, and the other on the Output Diode Heatsink Assembly). They are wired in series with either one being capable of open circuiting under heat duress. The more sophisticated Welders (Microprocessor controlled Inverter based Welders) usually incorporate two Thermistors (a type of Resistor with a Negative Temperature Coefficient) to achieve the same outcome, however a more complicated electronic circuit is now involved to measure the Thermal characteristics of the Welder while it is being operated.

When the Welders Specification is exceeded apart from shutting down and displaying a fault condition, the Welders internal Fan should operate in order to bring the temperature of the components Heatsink to a safe operating temperature. This normally occurs at around 158 degrees F (70 degrees C). This is the maximum tolerable temperature rating for most commercial grade electronic components. Mounted on the Heatsinks are either (or combinations of) Rectifier Diodes, SCR's, IGBT's and MOSFET's. If the Fan stops working or the Temperature Sense circuit fails, these components can be degraded or permanently damaged due to thermal stress.

Having to wait to complete a job due to a low Specification or an Over temperature fault is non productive and frustrating for all concerned. This is particularly so when on a project deadline, as time is money! When an electronic component fails due to thermal stress the Weldor's anxiety just increased by a tenfold factor. Now the Welder is totally inoperative until some trouble shooting can be performed. Once again...time is money!

When a Welders current is specified at 100% duty cycle the Weld Output Current can be maintained indefinitely, without the need for Welder cool down requirements.

Manufacturers publish specifications for their Welders in Operator Manuals, Service Manuals, and in Technical Sales Brochures. Unfortunately, the Weld Output current isn't always shown at a 100% DC rating. A conversion formula comes in handy under these circumstances.

To calculate the output current based on the duty cycle specification use the following formula:

I out = √ [((I rated x I rated) (DC Spec rated)) (DC Spec needed)]

From our previous example of 300 A @ 40% DC, we can now easily calculate the Weld Output Current for 100% DC, as follows:

I out = √ [((300 x 300) (40)) (100)]

I out = 189.74 Amps.

As you can see, the output current at 100% Duty Cycle is quite a bit smaller than the claimed 300 Amp rating of this Welder. Duty Cycle makes a difference!"

David Willcocks is an Electronics professional, and Technical writer. For more information on Automated Test Equipment please visit http://www.imagineATE.com

Charley Davidson
03-10-2011, 01:23 AM
not sure.... i just weld till it starts to smell funny, then let it cool for a few seconds..... ha!

So does it smell like apple pie or European cuisine?

WookieWelding
03-10-2011, 04:03 AM
USA standard is over a 10 min cycle EURO Standard is calculated over a 5 min cycle
so if you had say a stated 60% duty cycle that was Euro Standard it would be = to the USA standard of a 30% duty cycle

---------- Post added at 03:03 AM ---------- Previous post was at 03:00 AM ----------


Don't understand the question?...duty cycle is a percentage whether you use an hour or ten minutes it will be the same number.Think about how you would do it if you had a 140 amp mig or econotig where you knew it would not be able to perform for the hour you'd specify over ten minutes because it is the only way to measure it. I have had a look at the Longevity welder I have and it is made to heavy in some places like the tig cord wrap, it isn't goin to wear out from abrasion, inside heavy copper conductors, hand soldering on components most would only wave solder, telecom grade mosfets, dbl pole dbl throw switches, and something alot of us love to hate because it is so large the cooling fan.Enormous cooling fan to be exact.
Here is an article I found;


"Welders duty cycle rating (Specification) is an assigned figure of merit for sustainability of output current. It is expressed as a percentage of weld time over a 10 minute period (where 100% Weld On time equals 10 minutes) at a given output current. For example, let's consider the specification: 300A @ 40% duty cycle. A 40% duty cycle represents 4 minutes out of a 10 minute period that the Welder can operate. For the other 6 minutes, the Welder must be allowed to cool down. If not, the Welder will shut down and light an over temperature LED, or display a Thermal Error code. If this occurs the Weldor (a person who Welds Metal) has to stop production and wait for the Over temperature condition to clear. The more basic Welders (Transformer/ SCR based Welders) usually incorporate two bi-metallic strip type Thermostats (one on the Input Rectifier Heatsink Assembly, and the other on the Output Diode Heatsink Assembly). They are wired in series with either one being capable of open circuiting under heat duress. The more sophisticated Welders (Microprocessor controlled Inverter based Welders) usually incorporate two Thermistors (a type of Resistor with a Negative Temperature Coefficient) to achieve the same outcome, however a more complicated electronic circuit is now involved to measure the Thermal characteristics of the Welder while it is being operated.

When the Welders Specification is exceeded apart from shutting down and displaying a fault condition, the Welders internal Fan should operate in order to bring the temperature of the components Heatsink to a safe operating temperature. This normally occurs at around 158 degrees F (70 degrees C). This is the maximum tolerable temperature rating for most commercial grade electronic components. Mounted on the Heatsinks are either (or combinations of) Rectifier Diodes, SCR's, IGBT's and MOSFET's. If the Fan stops working or the Temperature Sense circuit fails, these components can be degraded or permanently damaged due to thermal stress.

Having to wait to complete a job due to a low Specification or an Over temperature fault is non productive and frustrating for all concerned. This is particularly so when on a project deadline, as time is money! When an electronic component fails due to thermal stress the Weldor's anxiety just increased by a tenfold factor. Now the Welder is totally inoperative until some trouble shooting can be performed. Once again...time is money!

When a Welders current is specified at 100% duty cycle the Weld Output Current can be maintained indefinitely, without the need for Welder cool down requirements.

Manufacturers publish specifications for their Welders in Operator Manuals, Service Manuals, and in Technical Sales Brochures. Unfortunately, the Weld Output current isn't always shown at a 100% DC rating. A conversion formula comes in handy under these circumstances.

To calculate the output current based on the duty cycle specification use the following formula:

I out = √ [((I rated x I rated) (DC Spec rated)) (DC Spec needed)]

From our previous example of 300 A @ 40% DC, we can now easily calculate the Weld Output Current for 100% DC, as follows:

I out = √ [((300 x 300) (40)) (100)]

I out = 189.74 Amps.

As you can see, the output current at 100% Duty Cycle is quite a bit smaller than the claimed 300 Amp rating of this Welder. Duty Cycle makes a difference!"

David Willcocks is an Electronics professional, and Technical writer. For more information on Automated Test Equipment please visit IGBT & MOSFET Tester, SCR Component Analyzer (http://www.imagineATE.com)
TIG i understand Duty cycle USA and EURO standard are calculated Differently is the reason i asked

Kel Fab Creations
03-10-2011, 11:03 AM
So does it smell like apple pie or European cuisine?

it's Lean Cuisine or European Cuisine

BradBlazer
03-10-2011, 07:41 PM
USA standard is over a 10 min cycle EURO Standard is calculated over a 5 min cycle
so if you had say a stated 60% duty cycle that was Euro Standard it would be = to the USA standard of a 30% duty cycle

---------- Post added at 03:03 AM ---------- Previous post was at 03:00 AM ----------


TIG i understand Duty cycle USA and EURO standard are calculated Differently is the reason i asked

I wouldn't agree with your statement. 60% over a 5 minute cycle means 3 minutes on and 2 minutes off. 30% over a 10 minute sycle means 3 minutes on and 7 minutes off. 100% by either method means the same thing. A 10 minute cycle may be a little more rigorous but by my swag there's not much difference.

WookieWelding
03-10-2011, 08:00 PM
60% duty cycle Euro 5 minute would be 3 minutes on 2 minutes off which mean you could not weld over 3 minutes continuous
60% duty cycle USA 10 minute would be 6 minutes on 4 minutes off Which mean you could not weld over 6 minutes continuous

SICFabrications
03-10-2011, 09:44 PM
wookie, so far, in my experience with longevity machines, the duty cycle is underrated..... they say 60% @ said amperage, but ive pushed them to see.... havent had one cycle out yet.... for example, i ran a migweld 250p @ 245 to 250 amps pretty much non-stop for 10 hours today.... *shrugs*

tigqk
03-10-2011, 10:02 PM
Holy @#$%@#$%@#$%@#$% wookie you sure like to citicize Longevity, find someone that has a machine locally, try it, and find out for yourself, then come back and post it, or use the formula.

WookieWelding
03-11-2011, 01:38 AM
I was simply asking a question

Nick
03-11-2011, 02:02 AM
Holy @#$%@#$%@#$%@#$% wookie you sure like to citicize Longevity, find someone that has a machine locally, try it, and find out for yourself, then come back and post it, or use the formula.

Decaf for this man. :lol:

The whole thing read like a simple peaceful clarification question, unless I missed some edited drama.

Gadget
03-11-2011, 08:26 AM
Nothing has been edited, it is just a reasonable and informative question and answer thread.

Nick
03-11-2011, 08:44 AM
Nothing has been edited, it is just a reasonable and informative question and answer thread.

Thought so. I'd wondered if being awake for 36+ hours had me missing details somewhere. :lol:

tigqk
03-14-2011, 04:04 AM
Sorry, sometimes get hot headed, did not think anyone was reading info.

Bunk
03-14-2011, 08:45 AM
I was trying to explane all this to my wife yesterday, now today I can do it! Thanks guys, learning every day...
Bunk

BradBlazer
03-14-2011, 12:02 PM
Here is an interesting chart comparing 5 and 10 minute duty cycle ratings for wire. I would guess that the comparison is valid for most devices. The difference is of course most pronounced at lower percentages and goes to zero at 100%. Doing a little interpolation, 60% duty cycle over 5 minutes is like 56% over 10 minutes. 35% over 5 minutes is like 30% over 10 minutes.

So IF your machine is rated at 60% over 5 minutes, you can probably lay a continuous bead for 5-1/2 minutes, then rest for 4-1/2 minutes. Remember this is a difference in test method, not fundamental machine function.

Olex Cables Australia - Catalogue Product Detail (http://www.olex.com.au/Catalogue-Products/CURRENT-RATINGS-WELDING.html)

Nick
03-14-2011, 01:43 PM
Sorry, sometimes get hot headed, did not think anyone was reading info.

No worries. The internet would get boring pretty fast if there weren't misunderstandings. :D

tigqk
03-15-2011, 01:12 AM
Anyone that is looking to buy and is comparision shopping with duty cycles should know that their have been some errors going to the new tables/new site design and check if they don't look right by looking at some posts.

WookieWelding
03-15-2011, 01:25 AM
when i shop for a machine first thing i look at is duty cycle reason i asked the original question cause of the difference in the two rating standards
I did not know there was a difference till my College Professor pointed it out

BradBlazer
03-15-2011, 09:51 AM
Still waiting for the answer to your original question - which standard does Longevity use?

rustycase
03-15-2011, 01:33 PM
when i shop for a machine first thing i look at is duty cycle reason i asked the original question cause of the difference in the two rating standards
I did not know there was a difference till my College Professor pointed it out

When I set out to purchase a new machine, my first consideration was reliability and support.

That meant blue and red, in my neck of the woods.

THEN, I looked at price, and function.

Outright, I could not afford the red or blue machine with the function I desired, so I stepped down... and lost capability.

The import machine offered so much more control over the process for many less $'s than cost of a red or blue entry level machine.

I re-considered support.

I could not justify so much higher a cost for support, which would bring me less function and opportunity to learn how to master the craft.

I AM a repairman, and hobbyist.
Duty cycle was considered, and given a lower priority.

Apparent duty cycle is very nearly the same, anyway.
Best
rc

LONGEVITY
03-15-2011, 07:28 PM
The duty cycle of our machines is rated at 10 minutes. Also, we really under rate our equipment as you can see based of SICFab's post. I guess apple pie wins!!!

WookieWelding
03-15-2011, 10:22 PM
I like Pie

180guy
03-18-2011, 07:29 PM
Good to know its on the American standard. These machines really seem to put out. lol

rustycase
03-18-2011, 09:27 PM
Aw shucks...

I LOVE PIE!

It's great at the end of the day, or even at the beginning of the day.
And I already survive on beans n' franks/ chili mac trying to get to that point.

Maybe some ramen here or there will hedge my bets so I can get to the point where I can take a deep breath and enjoy that pie.

...Me? I'd rather be fishing.
rc

matteh99
03-19-2011, 11:13 PM
I have had my 520D shut off only once due to over heating. The fan stopped and I didn't realise it. I welded for maybe 10 min at medium current and it shut off. I turned it off and then back on to get the fan to start after that it blew out a bunch of hot air and started working again. Since then I haven't managed to get the air blowing out of it to seem even slightly warm.

Eric

BradBlazer
03-22-2011, 12:38 AM
The whole thing seems like competitor FUD.

d4ve
04-03-2011, 10:41 PM
These welders keep sounding better and better. Great prices, rocking duty cycles, great support. If you guys aren't careful I'm going to end up with a really angry wife and bunch of new toys.

atcig
04-03-2011, 10:56 PM
Is it easier to get forgiveness or permission?

d4ve
04-04-2011, 09:31 AM
I find its a lose-lose situation. On one side it is like you got no balls and on the other side you might as well not have them. Let it be known that "the grudge" is not just a horror movie.

ISKI
04-20-2011, 09:58 AM
I think the confusion is from the two metrics and now I am not sure of my preconceptions. I thought that the duty cycle is set depending upon what the machine can handle. At high power the machine will change the on time to limit the power output. My Lincoln Ideal Arc 250 will put out 250 Amps all day and not go over temperature as it us rated for 100%. Now my Lincoln Precision TIG 185 set to 185 in the summer using an extension cord will run for a while and then sometimes over-temp and shut off. I thought that the machine was pulsing 185 Amps on and off at say 60% for a actual power of 108 Amps and if properly wired and cooled it would do this all day. As I stated on an extension cord, it has shut down in the past, but I didn’t think it really would ever give me 180 Amps but pulses of 180 Amps and the pulses controlled the heat/power so it should run all day. I thought the duty cycle of the on time was set so the machine would run all day, but never actually give me 180 Amps of continuous power. I’ll need to look this one up (interesting).

rustycase
04-20-2011, 10:21 AM
I'm fortunate, being in the hobby level, that duty cycle probably won't be a concern.
rc