Tek PS2521G in series with another PS - Max Voltage?

[CM]

Hello.  This may be a dumb question, but I wanted to get an independent opinion on this.  I am trying to generate 63V to check the maximum voltage (and maybe reform) some big old output capacitors in a power supply I am checking out.  The manual for the PS2521G explains how to run the two 20V outputs in series to obtain 40V.  It also goes over how to connect it in series with an "external" power supply to achieve higher voltages.  However, the manual (or the front panel) does not specify an output isolating rating.  If I run the PS2521G in series to generate 40V, can I safely hood that up in series to another power supply at 23V to generate 63V?  The PS was build to accept a mains input of 240V, so I'm guessing the output isolating rating is also 240V.  What is your opinion?  Thanks

[J-R]

I don't see how I'd have any concerns up to 72V since that is the official output rating of the sister model PS2520G, but beyond that I might on record vote for something that has documented limits.

The true isolation limit is probably hard to pin down, since humidity and PCB contamination for example can change things quite a bit.  The design is going to try to cover the worse case.

However, assuming all supplies are floating, you may find that the maximum voltage to ground will be lower than 63V.  You might measure -27V to +36V, for example.  So then you might be confident in reaching quite a bit higher.

You could also ground reference one of the outputs to force a result such as -23V to +40V.  Doing that is a mixed bag though, especially at higher voltages.  On the one hand you're trying to accommodate the isolation limit of one of the supplies, but on the other hand I think I'd rather have everything floating for personal safety reasons.  If I'm floating 250V for example, would I rather have -125V to +125V with a hard reference to ground for both high voltage points, or everything floating where as soon as I touch either output it basically equalizes to my level nearly instantly?  I'll solicit further discussion from the collective on that, perhaps...