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AC/DC Desktop adapter, non floating ground?

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ninjanation217:
Hello everyone, I have what I hope is a simple question.

I need a desktop power supply (wall wart) like this:
https://www.digikey.com/product-detail/en/mean-well-usa-inc/GST60A24-P1J/1866-2152-ND/7703715

but, I need the ground to be connected to earth ground. What spec do I need to be looking for to find this?

Thanks,

- James

Zero999:
I think the only way is to read the data sheet or ask the manufacturer.

In the case of the PSU you've linked to. It clearly has a floating output. Refer to page 3 of the data sheet:

--- Quote ----V not connected to AC FG
--- End quote ---
https://www.meanwell.com/Upload/PDF/GST60A/GST60A-SPEC.PDF

Why do you need the output to be grounded? Floating is generally better as it offers greater flexibility.

ninjanation217:
Thanks for your reply!

Yeah it looks like I'm just going to contact Mean Well or someone, as not all data sheets list the earth connection, turns out I'm looking for a grounding configuration of E1. I have found most of my laptop power supplies are grounded in this way.

I know its normally better, however in my particular case it helps.

I am making a photometer using TI DDC112. If I am not using an integration time of multiples of 16.66 ms (because of the 60 Hz mains, long story) I see a sine wave in my measurement at extremely low levels. however, I have found attaching earth ground minimizes this. I have tried filtering to no avail, so, I'm just attaching earth ground as its the easiest fix.

- James

ejeffrey:
This is probably caused by common mode leakage from the class-Y EMI capacitors in the power supply.  Connecting to ground gives an easier return path for the leakage current that through the rest of your circuit.

Does it have to be a barrel connector? Some power supplies use DIN connectors and connect the DIN shield to the input ground so that you can choose how to connect that with your circuit.  That gives the best of both worlds.

A medical rated power supply will have less ground leakage so will likely be considerably better than standard industrial/telecom power supplies even when floating.

Zero999:
If the power supply has an earth connection, it's less likely 60Hz hum will be an issue. The secondary side will most likely be connected to earth via a capacitor, so it's grounded at AC, even if it's floating at DC.

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