Mastech HY3005F-3 Series/Parallel Switches imply non-floating supply?

[tzcczt]

The HY3005F-3 has two switches for configuring it's two supplies in independent, series or parallel mode.  Does the existence of these switches imply that the two outputs are not truly independent/floating?

There is also a translated warning in the manual "In this series operation, must not connect the negative output terminal to the ground output terminal whether it is of master or of slave unit, because the connection will bring short-circuit of the subsidiary circuit".

I don't have a use case in mind, but wanted to know why one couldn't connect them in series with the center terminal connected to earth for an earth referenced positive & negative supply.

[Circuitous]

I don't have this power supply, but when the switches are set to "Independent" the outputs should be isolated from each other.
 
You can check:

• With the output turned off
• Set the switches to independent
• measure the resistance between the two negative connections

Someone else might have a better recommendation?

[tzcczt]

No continuity between the negative terminals when in independent mode.  There is continuity in both parallel and series mode.  I just received the schematic (attached) from Mastech and I'm looking it over now.

[saturation]

I do not own this unit.  At a glance, those switches appear to save the owner from using jumpers to make a series or parallel connection between CH1 and CH2.  In parallel, be aware of the rated current of the switch [ in theory, the device can deliver 10A] and in series the Vdc output isolation breakdown voltage; in series its unlikely to be an issue since the maximum series Vdc this devices outputs is <= 60-65Vdc.

For either mode to work, both CH must be isolated from each other and you do not earth any terminals. 

Some problems: if you earth the neg terminal of both CH, you will short out CH1.  In parallel mode, it should not cause DC problems, but you have a shock hazard in higher Vdc as earth ground is chassis ground of many appliances as well as DSOs: if you touched the pos terminal the circuit completes using earth if you touch anything earthed.  Earthing the neg terminal would also allow a path to receive RFI, and other common mode noise sources, into your power supply line.

You cannot use earth as a reference for a neg and pos supply because it will not form a full circuit.  You can put the PSU in series mode and use CH1 + as ground and split the supply.