Duty cycle

By Lawrence (*****)

Date 01-19-2016 12:27 Edited 01-19-2016 12:31

Welcome to the forum Mike

Website seems to work fine

Yes, with a lower current draw the duty cycle increases, but how often does a garage SMAW unit perform more than 2 minutes out of 10 ?

https://www.millerwelds.com/files/owners-manuals/O316U_MIL.pdf

By mad mike Date 01-19-2016 16:25

Thanks.

By 803056

Date 01-20-2016 02:02

You can calculate the actual duty cycle.

Example:

Given: Rated amperage = 200 amps
Rated duty cycle = 100%
Find new duty cycle if the machine is to be operated at 300 amps.

Ta = (200/300)^2 X 100% = (4/9)x100% = 44%

The value 200 is the rated amperage taken from the nameplate. Likewise the rated duty cycle is taken from the nameplate.

The value 300 is the actual welding current required. As one would expect, using the machine at a higher amperage rating is going to cause the machine to heat up quicker, so a longer cooling period is needed to prevent toasting the machine.

On the other hand, if the required amperage is less than the rated amperage, the machine can be used for a longer interval without overheating the machine.

Al

By 357max

Date 01-21-2016 06:40 Edited 01-21-2016 06:49

Note on the T-Bolt Specification Plate, notice that at a voltage and amperage ( Volts X Amps = Watts ) the machines duty cycle is determined. Without the T-Bolt Specification and using as an example - Rated at 60% duty cycle at 30 volts at 300 amps ( 9000 watts ) a 60% duty cycle. Therefore at 150 amps at 30 volts ( 4500 ) watts the duty cycle would be 100 + %.
Presuming the T-Bolt is rated at 20% Duty cycle at 25 volts at 150 DC amps - therefore 3750 watts. Reducing the amps to 75 and volts 25 - 1875 watts 40% duty cycle. Heat destroys a welding machine therefore the rectifier for DC causes enough heat to require a lower duty cycle. A 14" electrode would be consumed in about 1 minute or less.