Got my hands on a DL3021 yesterday and was able to compare it to my Maynuo 9712. Initially I started experimenting just with a multimeter in diode test mode at its terminals. Immediately I found some severe shortcomings that shouldn´t happen to an experienced test equipment manufacturer, especially since already two firmware updates had been released:
In constant current mode, the output wouldn't switch off if you select it to via the on/off button, as long as the input current is approx. less than 5mA. A further investigations shows that this relates to zero current being displayed on the DL3021´s panel to be flowing in the external circuit. In this case, the instrument wouldn't switch off the passbank transistors. Since the instrument´s current measurement deadband is considerable at 3...5mA, you may end up connecting the device in "off load" mode to a circuit while the passbank is at a dead short. So far, i didn´t check how much current will flow upon connecting a powerful source and how long it will take the instrument to open the passbank and if it makes any difference, regarding the round about 4µF of capacitance across the DL3021´s input terminals that need to be charged. But anyway, I think this bug is an absolute no-go, off means off, regardless of the amount of external current flowing. I guess this can probably be addressed by a firmware update. Accuracy-wise in the low current ranges, the Maynuo wins against the Rigol hands-down. I wonder who came up with that brilliant idea to use a 500µOhms shunt resistor on that instrument...
Yet, as long as "macroscopic" currents are flowing, the load appears to work as it should (as far as I can tell).
Edit: What I really like about the load is the user interface (excluded the catastrophic front panel design). Configuring dynamic patterns is a no-brainer due to the elaborate graphic templates. Also, the current/voltage graph is a nice gimmick, yet I would have liked both current and voltage graph displayed contemporary in different colours on the same screen. Actually, that might be added in future via firmware update. Also, the choice to trigger the graph display properly would be a big plus (either by voltage or current)
What I don´t understand at all is that Rigol doesn´t appear to offer the user to chose which parameter (s)he wants to vary in [con]tinuous mode: As far as I cunderstood (I hope I´m wrong...), only current can be varied, neither voltage, resistance or power? Bummer! Rigol, I'm expecting a substantial firmware update. Along with the add-ons in battery test mode requested by contributors before.
In its current condition, I wouldn´t recommend to purchase the DL30XX. It´s got potential, no doubt, but this requires still a lot of initiative by Rigol, preferably in close contact with first-hour users of the instrument. If Rigol gets all these issues sorted, the DL30XX can turn into the "killer-load" and dominate the main stream market in this power class. But it´s still a considerable way to go I would say.
Cheers,
Tom