Hi, I have one of these bench switching power supplies. It delivers up to 30v and 10A. The problem is that when I set it, let say 20V and a tiny amount of current, let say 50mA, when I shorten it, at first a big spark jumps and several amps goes and after that reduces to 50mA. Is that normal, as it burns my components once I touch them? If it's not normal, in what section to search for the problem? Anyone had a similar problem? Any direction is welcome. Thank you very much
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This behavior is absolutely normal. The way of use is not quite right.
Any voltage source has a filter capacitor at the output, which is an integral part of the stability strategy.
When you connect a load to the output of the source, first this capacitor discharges to a current that is not controlled by the source and only then does the current stabilization loop come into operation.
Any voltage source has a filter capacitor at the output, which is an integral part of the stability strategy.
When you connect a load to the output of the source, first this capacitor discharges to a current that is not controlled by the source and only then does the current stabilization loop come into operation.
Thank you for your answer. My thoughts were similar. I was thinking of reducing the output capacitance, but this could destroy the whole operation.
Try setting the current limit to the desired limit. Then reduce set voltage to 0, connect device under test, then raise supply voltage gradually. Is this a viable approach?
That's normal for a SMPS, but good analog lab supplies regulate and current limit after the filter caps, so the current limiting always works immediately. Fortunately SMPS need much smaller output caps so the energy is small - and we are not commonly testing circuits that suddenly short out, but capturing thermal-runaway or overdriving an amp, and the transient is less abrupt.
Well that's my understanding based on a small sample of a few analog and one switch-mode supply(!)
I have a mix of older analog HP supplies in my basement hobby lab, and a few SMPS in the upstairs office (work lab) and my observation parallels Mark's comments above. For low noise, low power applications old HP and Agilent supplies purchased on eBay or at a ham fest are hard to beat.