Author Topic: Siglent SPD3303X-E sparks between positive and earth terminal  (Read 227 times)

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Offline szszoke

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Hello!

I picked up my first lab power supply after years of not having anything. It is a Siglent SPD3303X-E.

This is a linear power supply with two independent outputs that can be connected in series or parallel. As far as I know, the outputs should be "floating".

I turned the power supply off but I still had it plugged in to the wall. I started measuring the spacing between the banana terminals with a caliper. I measured them by the base, where some metal is exposed.

When I bridged the positive output of channel 1 with the green earth connector and I saw a spark. It was not big, and it did not spark again while I kept measuring things. If I'd have to guess, I shorted a capacitor.

As far as I can see, nothing is broken.

I tried measuring the voltage between the earth connector and the positive output terminal of channel one but it's only a few millivolts.

So, to the question:

Is this normal?

The only thing that I can think of is that there is a capacitor between earth and the output terminals (I've seen this in some power supply designs) and when I touched the output connectors with my caliper, I shorted that capacitor.
 

Offline tautech

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Re: Siglent SPD3303X-E sparks between positive and earth terminal
« Reply #1 on: April 14, 2021, 08:53:08 pm »
Cap would be my guess too. The Earth terminal is at mains earth potential if the need arises to couple it into your circuits for any reason.
 
Yes the outputs on these PSU's are floating and there is a 500V isolation spec from mains ground.
When in series mode several of these PSU's can have their outputs series'ed to supply a max of 500VDC.
Avid Rabid Hobbyist
 

Offline Manul

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Re: Siglent SPD3303X-E sparks between positive and earth terminal
« Reply #2 on: April 15, 2021, 01:10:30 am »
SPD3303X-E has 100nF capacitors from each channel to mains earth. It is for sure possible to see a little spark if this capacitance gets charged to more then a few volts. Normally it should not charge to high voltages by its own. Something external connected to the output might do it.
 

Offline szszoke

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Re: Siglent SPD3303X-E sparks between positive and earth terminal
« Reply #3 on: April 15, 2021, 06:54:19 am »
Thanks for the info!
 


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