I've got a welder (Thermal Arc 185) that features an adjustable AC high frequency control. It'll change the AC frequency from 15Hz to about 150Hz IIRC. I've looked in TA book as well as others and can not find anything which talks about what this adjustment does on a practical level, nor can I find anything that gives suggested settings.
What effect should I see when changing the AC frequency? Are there any rules of thumb about how to use it? Should I be changing frequency to address any problems? I'm new to welding aluminum and any changes that may be happening are difficult for me to discern. I just started a welding class, and the instructor there couldn't give me an answer off the top of his head.