I've now fried a couple of switch mode Mastech 30V, 50A regulated variable DC bench supplies. The first one when I was making some connections by just touching wires together and probably caused a spike? On the advice of a member here, on the second one, installed a Schottky diode in the + output cable. I was recently testing a defective 15 Watt ballast which flickered heavily and before I could disconnect it, poof went my PS. In both cases the displays died and in the latest case, it still produces Voltage that is variable but won't sustain a load.
I've been told by some that a switch mode DC PS is not really the best PS to use for running HID ballasts - which is my primary use. I don't remember what they're called but it was suggested that something like an "SDR"? the older, bigger, heavier supply would be better. I don't think "Linear" was the word they used. I want something in the neighborhood of 30V & 50-60 Amps, which, I know will require 240V input which is not an issue and I know it will be over $700. It needs to be variable and to be able to run in both constant voltage and constant current modes. It doesn't matter if its somewhat big and heavy as I can sit it on the floor. I found a U.S. made Lambda 40V-60A for $1200 but I'm gun-shy to get another one and end up frying it, too.
Lastly, I was told that there needs to be two "diodes" used to protect against reverse power flow and "something else" (again, I was not fast enough to absorb everything said). I heard the term "blocking diode" but it looks like something that is used in solar power systems?
So I'm seeking advice on:
1. What type (and brand, if important) of Variable Regulated PS to buy
2. How to protect it.