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Would it be safe to connect two identical AC/DC converters in series if they share the same AC source? My concern is that the negative DC output is grounded somewhere in the converters causing the second AC/DC converter to be shorted.

AC/DC Converters in Series

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    \$\begingroup\$ It depends on the converter. If it's output is galvanically isolated from the input, like the 'old' simple transfomers, it can work. \$\endgroup\$ – JimmyB Aug 23 at 13:05
  • \$\begingroup\$ Use a DMM to check if the output is grounded. \$\endgroup\$ – Marko Buršič Aug 23 at 13:11
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    \$\begingroup\$ The connection I'd put a '?' against is the ground on one side of the AC input. A commercial AC-DC converter will almost always be isolated (the ones you build yourself from a helpful youtube video of a capacitor-input rectifier AC-DC converter are not) so you can do pretty much anything with the outputs. \$\endgroup\$ – Neil_UK Aug 23 at 13:18
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    \$\begingroup\$ If you do ground the outputs, only ground one of the points you've shown, never both! Grounding both would result in one of the converter outputs to be shorted. Most AC-DC converters are isolated, so it should™ work. Do check for yourself however. \$\endgroup\$ – Richard the Spacecat Aug 23 at 13:34
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The AC/DC converter outputs need to be galvanically isolated from the AC input. Modern high frequency switchers often use switching transformers to provide the isolation. You show two grounds with ? marks. Select only one to be grounded. You can have a +/-12V or single ended 24V. And keep the DC ground isolated from the AC ground.

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Yes, you can gang power supplies this way, as long as they have floating (isolated from mains) secondaries. Choose the lower one’s (-) as a secondary reference. It need not be tied to safety ground but there’s no harm if it is.

There’s no specific requirement to have grounded AC input either. But make sure the PSUs are designed to support that.

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