Ok, before each recording that can last for a few hours a calibration can be done, at this point load can be disconnected but I don't think it is necessary. after calibration is done measurement for a few hours takes place and in all those times range changes automatically. the range changes when current drops below 10% or exceeds 90% of the range. as I said the problem is when range changes there are ugly unwanted bumps. but other that that it works Ok.