Duty Cycle

[WookieWelding]

Does longevity use the USA standard or the EURO standard for Calculating Duty Cycle ?

[180guy]

Good question.

[SICFabrications]

not sure.... i just weld till it starts to smell funny, then let it cool for a few seconds..... ha!

[tigqk]

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]

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]

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

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

[Kel Fab Creations]

So does it smell like apple pie or European cuisine?

it's Lean Cuisine or European Cuisine

[BradBlazer]

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]

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]

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*