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

Flow work - thermodynamics , Flow work: Flow work is energy possessed ...

Flow work: Flow work is energy possessed by the fluid by virtue of its pressure. Displacement Work: When piston moves in cylinder from position 1 to 2 with vo

Scanning electron microscope, 1- Explain the rationale of using a small WD ...

1- Explain the rationale of using a small WD to improve resolution. 2- In a tungsten SEM , Why does a high accelerating voltage provide the potential for higher resolution?  Why

Carbon monoxide-general safety tips , Carbon Monoxide:  If the engine has ...

Carbon Monoxide:  If the engine has to be started make sure the area is well ventilated. Never start the engine in an enclosed area without using the exhaust duct, since exhaust g

Maximum stress failure criterion, a) Determine the value of σ 0 to cause f...

a) Determine the value of σ 0 to cause failure when θ=30°, according to the maximum stress failure criterion.  Consider both σ 0 > 0 and σ 0 e.g. "failure in longitudinal tens

Heat pump - thermodynamics, Heat Pump - thermodynamics: Heat Pump: H...

Heat Pump - thermodynamics: Heat Pump: Heat pump is reversed heat engine that removes heat from a body at low temperature and transfer heat to the body at higher temperature

First law of thermodynamics, First law of thermodynamics: The First La...

First law of thermodynamics: The First Law of Thermodynamics states that work and heat are equally convertible. The present tendency is to include all the forms of energy. The

Solid Mensuration, How di i get the volume of a regular pentagon if the giv...

How di i get the volume of a regular pentagon if the given was a height of 9", a base of 3" and a central angle of 75

Engine lubrication system , Engine Lubrication System: This system facilit...

Engine Lubrication System: This system facilitates the lubrication of all the engine components, gears and other associated parts.

Illustrate moisture content test, Q. Illustrate Moisture content test ? ...

Q. Illustrate Moisture content test ? Moisture content test: Moisture is an important constituent of moulding sand. Its content in the moulding sand can be estimated as given b

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