| Electronics > Beginners |
| Confused with about my new Lab/Bench PSU C.C. & C.V. Is it working correctly? |
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| castingflame:
"If you want to see your power supply enter CC mode, then first you have to set a low current limit, and secondly you need to increase the load until it tries draw more current than the limit. If you do that then the supply will start limiting the current and the CC indicator will light." My point entirely! With my load connected I want to set a ceiling of 2Amps using the C.C. mode. Hitting the CC mode lights up the CC LED but, I CAN NOT set the CC limit. The CC controls do nothing. I have had a CV CC bench PSU before and that worked as expected. Anyhow, It is being returned and I now have a different Lab PSU being delivered Monday. |
| ArthurDent:
“However, you all completely missed my comments…” No, several posters have told you how to set the current limit as I did in post #8 and the quote from your power supply manual in post #7 clearly describes. The output voltage is ‘potential’ and can be displayed and adjusted with no load but the current output is only non-zero if there is a load, either your load, or a short across the output terminals that is described as the way to set the current limit for your supply. Without a load, or a short to allow you to set the limit, you can turn the current knob from one limit to the other and there will be absolutely no change in the current display because there is no load. Some supplies like this will go from CV to CC without a load if the current adjust knob is set to zero but this will only show that the auto crossover works at zero and isn’t of much practical use. The power supply described above with a 3-position load switch that internally shorts the output does the same as externally shorting the leads. Some higher end power supplies have the ability to set the current limit without shorting leads but your power supply doesn’t appear to have that feature built in. Here is a photo of a supply I have that can set overcurrent and/or overvoltage limits without a load. Unless you buy a power supply with the feature I described built in, or an output shorting switch, the next supply you get won’t work any differently. |
| IanB:
--- Quote from: castingflame on August 12, 2018, 11:25:44 am ---With my load connected I want to set a ceiling of 2Amps using the C.C. mode. Hitting the CC mode lights up the CC LED but, I CAN NOT set the CC limit. The CC controls do nothing. --- End quote --- Did you install a short circuit across the output terminals before trying to adjust the CC limit, as you are required to do? If you did not do so, then you are not using the instrument correctly. |
| castingflame:
Thanks again for your replies. Well my new power supply came today, this one... https://www.ebay.co.uk/itm/DC-Linear-Bench-Power-Supply-Variable-Output-0-30V-0-5A-0-5A-0-30V/123219732357?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 and I put it through its paces with my new DC Load ... https://labtronix.co.uk/drupal/shop/electronicload/3715a and everything worked as expected. Everything is great. All of the protections and limits are working and I am a happy bunny. I had a 0.1R resistor on the other PSU and I still could not get a CC setting to change. I did not however short the leads together so you may well be correct but I tried with and without a load. All in all I am much happier with the new PSU anyway as the old one also used to give a full channel output if I moved the dial sometimes. I saw it when I had 12v bulbs as a load, they would go full power for 0.5 of a second. That is not great. Anyway, thank you all for being patient and taking your time to give input. I am a happy to continue with my project Paul |
| ArthurDent:
The new power supply you chose is far superior to the last one you had. If you compare each half of your new power supply to the one I have that I showed in post #21 you will see that it has almost exactly all the same functions. Whether the previous one you had worked or not, I think you'll be much happier with this one. I think you made a wise choice. |
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