OK, sure. I will try to explain the background of the problem:
The application is that we own a very good quality (and VERY expensive)
30 KW regulated power supply that was designed to put out anywhere from ~150 VDC to 1500 VDC at up to 20 amps. And it works OK within its design range, but occasionally we need outputs as low as 50 VDC, and the supply becomes unstable at those very low settings. (And we can't afford to just go out and buy another supply.)
So, I thought that I might be able to "trick" the supply into thinking that it is working into a 150 volt load while actually applying only 50 to the load. (And, by the way: The load is an ionized gas plasma, and its impedance can vary rapidly over a wide range.)
Duty cycle would be "continuous" i.e. several hours at a time. Accuracy is not super-important; 5% would be fine, and even 10% might work.
'Transient-response' is an interesting question! The existing power supply has a lot of very complicated (and proprietary) circuitry built into it to maintain constant output voltage even while the load impedance is changing abruptly. I'm not sure, but I think that it also has circuitry to momentarily turn the output voltage OFF for a few microseconds if the load impedance goes below some critical threshhold (i.e. if a localized, intense arc forms in the plasma.) I suspect that an 'active' voltage dropping device with a finite response-time might confuse the control circuitry quite a bit, but I'm not sure. At the present time, we are using resistor banks for the voltage-dropping, but this is not really satisfactory because the current can vary so much, depending on the gas pressure & composition.
Hope this helps to clarify the problem.