Duty cycle rating, Mechanical Engineering

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.

 

 

Posted Date: 9/14/2012 4:22:26 AM | Location : United States







Related Discussions:- Duty cycle rating, Assignment Help, Ask Question on Duty cycle rating, Get Answer, Expert's Help, Duty cycle rating Discussions

Write discussion on Duty cycle rating
Your posts are moderated
Related Questions
Q. How can we use Cereals? Foundry cereal is finely ground corn flour or corn starch. It (0.25-2%) increases the green and dry strengths of the moulding sand. Since the cereal

#question. how much the strength coefficient of 383 cast alloy , to calculate the quality index .

Q. Describe Elastic and plastic deformation? When a sufficient load is applied to a metal or other structural material, it will cause the material to change shape. This chang

Explain Newton's Law of cooling. What do you mean by convective Heat Transfer coefficient ? What are the factors on which co-efficient of convective heat transfer (h) depends upon

How do I solve this question? http://i195.photobucket.com/albums/z154/NanazRulez/20120802_155751.jpg

what is tangential force in metal cutting

Define Essentials of Milling Fixture? Strength of withstand heavy forces. Thrust should be directed towards a strong, solid structure. Cutter setting piece should b

importance of workshop in mechanical


Discuss any three of the following:- (i) Electron Beam Welding (ii) Friction Welding (iii) Thermit Welding (iv) Gas Welding Give their advantages, Limitations, and a