SiPMerlin150
Member
- Messages
- 987
- Location
- Sunshine Coast, Queensland
I have a basic and old sip 'merlin 150' arc welder, the unit comes with no cooling other than a perforated case, and if used for more than just the odd weld here and there, you will be experiencing a problem with the very short cycle times.
The problem isn't too apparent when you use the machine for the first time of the day, but once the transformer has become hot, the time between use and cooling is literally a minute of two.. Very frustrating!
Now the most effective solution is get rid of this old unit and purchase and inverter that has a higher efficiency, but sometimes that spare money isn't available..
I've reduced the cooling off time from 10 - 15 minutes down to 5 or 6 minutes on my welder and the duty cyles are as follows:
25% power @ 55 - 65 amps - 45% duty cycle - 4 mins 30 seconds arc time
50% power @ 85 - 95 amps - 33% duty cycle - 3 mins 24 seconds arc time
75% power - untested - my guess is 20 %
100% power - untested - my guess is 10-15%
These results were done from a stone cold transformer and once the first thermal cutout has been reached, and a 6 minute cool off period allowed, you literally have only half of what is stated as above. This is due to a less efficient transformer design, steel core with heavy copper wire windings.
Simply meaning that the transformer is inefficient at shedding waste heat that is produced during its operation.
With a fan installed in the case, with a moderate amount of air flow, lets say 30 cfm flow will decrease the time it takes to cool down the unit below its thermal cutout, from 15 minutes to 6 or 7, but waiting a full 15 minutes will give you back at least 70% of your duty cycle.
Increasing air flow will possibly see this units performance increase, but only marginally.
The fan i installed was a 250v ac tubeaxial fan, shifting 30 cfm of air and was connected up to the on off switch to run continuously whilst the welder was plugged in.
Hope i haven't bored anybody by rambling on
The problem isn't too apparent when you use the machine for the first time of the day, but once the transformer has become hot, the time between use and cooling is literally a minute of two.. Very frustrating!
Now the most effective solution is get rid of this old unit and purchase and inverter that has a higher efficiency, but sometimes that spare money isn't available..
I've reduced the cooling off time from 10 - 15 minutes down to 5 or 6 minutes on my welder and the duty cyles are as follows:
25% power @ 55 - 65 amps - 45% duty cycle - 4 mins 30 seconds arc time
50% power @ 85 - 95 amps - 33% duty cycle - 3 mins 24 seconds arc time
75% power - untested - my guess is 20 %
100% power - untested - my guess is 10-15%
These results were done from a stone cold transformer and once the first thermal cutout has been reached, and a 6 minute cool off period allowed, you literally have only half of what is stated as above. This is due to a less efficient transformer design, steel core with heavy copper wire windings.
Simply meaning that the transformer is inefficient at shedding waste heat that is produced during its operation.
With a fan installed in the case, with a moderate amount of air flow, lets say 30 cfm flow will decrease the time it takes to cool down the unit below its thermal cutout, from 15 minutes to 6 or 7, but waiting a full 15 minutes will give you back at least 70% of your duty cycle.
Increasing air flow will possibly see this units performance increase, but only marginally.
The fan i installed was a 250v ac tubeaxial fan, shifting 30 cfm of air and was connected up to the on off switch to run continuously whilst the welder was plugged in.
Hope i haven't bored anybody by rambling on