DP832: How to use two channels for voltage greater than 5V & common ground

[abhayb_e]

Hi,
    I am a beginner & setting my electronics lab. Recently i purchased a lab power supply DP832. For CH2 & CH3 there is a common ground. But here CH3 is limited to just 5V while CH2 is 30V which is sufficient. So here if we need to supply a circuit two voltages(with common ground) both greater than 5V then we cannot use CH2 & CH3. All the channels are isolated from earth ground.
For this scenario can we use CH1 & CH2 but CH1 is isolated from CH2 as given in spec ? Can we use Chassis ground( GND-chassis) as common ground ? If yes how do we make the connections ?
"Chassis ground" as given in the QuickGuide of DP832 as "This terminal is connected to the instrument chassis and ground wire (power cord ground terminal) and is in grounded state.”.

regards
Abhay

[LaurentR]

NOTE: You probably should have posted this in the beginner section.

Ch1 and Ch2 are isolated to give you the flexibility to use them independently, but you can also tie them together in various ways (series, parallel...).

In your case, tie your circuit ground to the (-) terminals of both Ch1 and Ch2. You can do that any way you want (e.g. tie Ch1 (-) and Ch2(-) at the DP832 then bring a single wire to your circuit), then use Ch1 (+) and Ch2 (+) as your 2 supplies.

Whether you also connect the DP832 chassis ground (which is earth main ground) to your circuit ground is an independent question. In general, there is no need. Regardless, it doesn't functionally change the behavior of the DP832.

[abhayb_e]

Thanks for reply LaurentR.
This seems to be a basic feature of lab PSU so may be beginner section was better.

There also a application note by Rigol "Connect Power Supplies in Series or Parallel".
http://beyondmeasure.rigoltech.com/acton/attachment/1579/f-01d0/1/-/-/-/-/file.pdf.

Actually i tried to find on internet if someone has actually tried & demonstrated this feature work correctly on DP832 specifically but i could not find any such video or any demonstration.
It seems to me,  as mentioned by you LaurentR, connecting (-) of both CH1 & CH2 should work correctly but will it work correctly specifically on DP832, has anybody done this on DP832 seen it work correclty.
I don't want to try it & damage some device, too expensive to learn by my own mistakes.

[LaurentR]

It'll definitely work, no worries.

There also a application note by Rigol "Connect Power Supplies in Series or Parallel".
http://beyondmeasure.rigoltech.com/acton/attachment/1579/f-01d0/1/-/-/-/-/file.pdf.

What you're doing is similar to the "parallel" mode except you're only tying the (-) together.

Note: if you were to also use Ch3 with the same common ground, it is possible, but be aware that its (-) terminal is only weakly connected (through a sense wire) to the Ch2 (-), so if you need to tie them together, do it externally, don't rely on the internal connection. See this appnote from Rigol.