When to use chasis GND on triple output bench PSU ?

Thread Starter

DarthVolta

Joined Jan 27, 2015
121
I have my 1st proper bench PSU. It's a Siglent SPD3303X-E, seems quite nice so far. It's all linear, not SMPS. It has 3 independent outputs, each with it's own +/- terminal, and that's all isolated from chassis GND (at least when it's turned off anyways, I didn't want to check contin. when powered). And there's also a chassis GND terminal, connected to mains Earth-GND. CH1/2 can operate in series or parallel mode.

Does it have to be used anytime I want to connect the (-) terminals together , in independent mode. And then would I just connect the (-)'s to (GND) ? The instructional manual doesn't seem to say, they just label it, I don't see it mentioned after that.

Also in series mode, you use CH1(-) and CH2(+) for up to 64V. What if in independent mode, you want to stack the channels like any other 2 voltage sources ? I never used multi-rail bench PSU before.

This is more the overview pdf
https://www.batronix.com/pdf/Siglent/SPD3303X/SPD3303X-Datasheet.pdf

Here the user manual
https://www.manualslib.com/manual/1340833/Siglent-Spd3303x.html
 

MaxHeadRoom

Joined Jul 18, 2013
19,042
There is no need to connect the power commons to earth ground if not required by connected equipment etc.
Just leave them floating.
Max.
 

crutschow

Joined Mar 14, 2008
23,353
Normally the chassis ground connection is not connected, but is sometimes used when testing high-frequency circuits to minimize radiated interference.
Also in series mode, you use CH1(-) and CH2(+) for up to 64V. What if in independent mode, you want to stack the channels like any other 2 voltage sources ?
You should be able to connect them in any series order, as long as you don't exceed any voltage limits for such a configuration.
With that caveat, the three outputs should act the same as three separate supplies.
 

Thread Starter

DarthVolta

Joined Jan 27, 2015
121
Ok so I don't need to worry about it MEGND for most stuff, thanks. And I can stack them if I wanted.

So right now I want to power a small PCB with CH1, and add inputs from CH2/3, all sharing a common (-) terminal. So should I connect all 3 (-) together on the PSU, and only run 1 COM wire to the DUT ? I know of gnd loops and gnd plane issues, but I can't say I'm right on that either.
 

MaxHeadRoom

Joined Jul 18, 2013
19,042
So right now I want to power a small PCB with CH1, and add inputs from CH2/3, all sharing a common (-) terminal. So should I connect all 3 (-) together on the PSU, and only run 1 COM wire to the DUT ?
One conductor of sufficient gauge should suffice for the commons.
When referring to power supplies, I prefer to use (power) Common (COM) rather than the minus sign as some P.S. have a neg-0v-pos outputs.
Max.
 
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