Duty cycle rating, Mechanical Engineering

Assignment Help:

DUTY CYCLE RATING


Since, arc welding power sources are delivering high currents for welding; the components of such a system are bound to get heated. In order to have increased life of such components the heating should be limited. This is done by specifying what is called as "Duty Cycle". The duty cycle is explained as a percentage and at a particular current level.

Example: 60 % duty cycle at 400 A This specification says that 400 A welding current can be used continuously upto 60 % of a base period. The base period for duty cycle calculations in many of the standards is five minutes.60 % of five minutes is three minutes. Which means 400 A welding can be done without break for three minutes and for two minutes the power source should be allowed to cool down. Fig. shows the duty cycle rating.

989_duty cycle 1.jpg


If the same power source is used to deliver 500 A welding current then to avoid over heating of power source components the duty cycle has to be reduced.

759_duty cycle 2.jpg

Since the heating is proportional (I2R) the duty cycle rate for different currents are related by this simple formula.

                   I21T1=I22T2

If we now want to calculate the duty cycle for 500 A then,


                    = (400 / 500)2 X 0.6
                    = (4 / 5) 2 x 0.6
                    = (16 / 25) x 0.6
                    = 38.4 %


which means 500 A current can be used for 1.9 minutes without break and the power source should be allowed to cool for 3.1 minutes before next welding. For automatic welding applications the power source should be rated for 100 %  duty cycle (continuous current) at the desired welding current.

 

 


Related Discussions:- Duty cycle rating

Calculate for the resultant of the force system, Calculate for the resultan...

Calculate for the resultant of the force system: A rectangle ABCD is having sides AB = CD = 80 mm and BC = DA = 60 mm. Forces of 150 N each of them act along AB a

Aerospace engineering, Have you ever been sit on a flight? Have you ever th...

Have you ever been sit on a flight? Have you ever think how those gigantic machines are developed ? Aerospace engineering is just the place where you require to be. Aerospace engin

Truss, how can we modified truss to make sure it can support 20% more force...

how can we modified truss to make sure it can support 20% more forces than usual?

Determine lifting load of crane, Navy divers are called to rescue a group o...

Navy divers are called to rescue a group of office workers trapped in a basement under floodwater in Leeds, UK. The only access to the basement is via a 1.5 x 1.5 m horizontal hatc

Heat exchangers - air-conditioning guidelines, Q. Heat Exchangers - air-con...

Q. Heat Exchangers - air-conditioning guidelines? Location, size and capacity clearly indicated. Control valves indicated. Space for tube removal, keep space clear of pipes, va

D.c circuits, formulae for finding gross torque developed by the armeture

formulae for finding gross torque developed by the armeture

How much Torque required, hi how much torque required to move 100kg in a sk...

hi how much torque required to move 100kg in a skate board with a wheel diameter of 1.8 inch

Heat dissipation -various factors in clutch design , Heat Dissipation : Du...

Heat Dissipation : During clutch application, large amount of heat is generated. The rubbing surfaces should have sufficient area and mass to absorb the generated heat. The proper

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd