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| E36300 Series Programmable DC Power Supplies (E36311A, E36312A, E36313A) |
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| rsjsouza:
You guys are onto something. I don't have a differential probe, but I did some measurements with the grounded oscilloscope at an outlet further away from the power supply. The amplitude is reduced in Ch1, despite some oscillation is still seen in Ch3 (grounded at the load). The picture below shows both channels plus Ch1-Ch3. All previous parameters are applicable. Another interesting detail: if I switch the power supply continuously, the spike is reduced - perhaps some Y capacitors become a bit charged and dampen the spike. |
| 2N3055:
--- Quote from: rsjsouza on August 20, 2018, 01:54:44 am ---You guys are onto something. I don't have a differential probe, but I did some measurements with the grounded oscilloscope at an outlet further away from the power supply. The amplitude is reduced in Ch1, despite some oscillation is still seen in Ch3 (grounded at the load). The picture below shows both channels plus Ch1-Ch3. All previous parameters are applicable. Another interesting detail: if I switch the power supply continuously, the spike is reduced - perhaps some Y capacitors become a bit charged and dampen the spike. --- End quote --- As I said, it is connected to large switch-on current transient, which is combined from current to establish magnetic field in a transformer, combined with virtual short circuit on secondary (made from bridge rectifier and large, empty capacitors). Probably a soft start circuit would make it much better. |
| rsjsouza:
Yes, I agree. The large switch-on current transient is most certainly the main transformer itself being connected at all times to the mains. The reason for my suspicion is that in standby it consumes 10W (17VA) and when it is turned on it increases by about 1W (11W / 18VA) - no load. The power factor is what you would expect of a transformer. When I float the PS and use the two oscilloscope channels to measure the output, the waveform is quite similar to the first ones I have sent. |
| pe1oxp:
--- Quote from: pe1oxp on July 31, 2018, 11:01:37 am --- --- Quote from: LaurentR on July 30, 2018, 06:41:59 am --- --- Quote from: pe1oxp on July 30, 2018, 06:25:29 am ---Just curious, how do they swap the power supplies? Do you get a 'new' one ore just one out of the poo which is modified? This because mine are almost 'new in box' and won't get a replacement with a bunch of scratches --- End quote --- I got mine back this week. I got a new unit (I had asked for it - not sure if that's std). Funnily enough, it didn't come with a box at all, it was brought by a Keysight-branded courier as is (they are not joking when telling you to not send any accessories - even the terminal blocks). My wife had no idea what it was and I found it laying on the kitchen table, side handle up ::) --- End quote --- Thanks for your reply. Will look for another box before I ship the power supply. So I can keep the original box for calibration of repair. Hopefully they will ship it back in a box otherwise it can be damaged at the local bookshop before i can pick it up --- End quote --- Keysight picked up my power supply at August 14, no packaging needed, al done by there own courier. Received the new one back yesterday (August 29) in a big carton box brought by GLS. So it took 2 weeks to swap the power supply including full calibration of the new one (ISO17025) |
| nctnico:
--- Quote from: nctnico on August 19, 2018, 08:34:39 pm ---I'll do some tests myself when I can. I'm pretty sure these transients are induced into the ground loop between the PSU and the oscilloscope and are not actually present on the outputs. --- End quote --- I finally did some testing. The transients are definitely ground loop related. I also tried a different PSU which has a relay at the output and I get similar spikes when the mains are switched on. All in all I have to conclude that Keysight has fixed the power on spikes on all channels with the hardware modification / newer models :-+ |
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