Do Hot Swap PSUs Risk Phase-to-Phase Voltage Exposure?

AI Thread Summary
Hot swap PSUs in data center servers are designed to allow individual modules to be replaced without shutting down the system. Concerns arise regarding the potential for phase-to-phase voltage exposure, particularly in setups where PSUs are powered by different phases in a 240-volt system. It is crucial that these systems prevent any AC mains voltage from connecting to the low current lines, as this could create dangerous voltage differentials. The design should ensure that any connections between swappable PSU modules and the common power circuitry are safe and compliant with voltage standards. Overall, proper design practices should mitigate the risk of cross-phase voltage exposure in redundant hot swap PSU configurations.
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I'm looking for information on how hot swap PSUs as used in computers (used typically for data center servers) are designed. In particular, I want to focus on the common aspects between the 2 or more PSU subunits that can be swapped. What kinds of connections are made between the individual swappable PSU module, and the common power circuitry? Is there any chance the any mains AC voltage would go across this connection, or by any other means, even if it is intended as a low current or current limited connection? What I am wondering about is whether this could be exposed to a phase-to-phase higher voltage (e.g. 416 volts) if/when the individual PSU modules are powered by separate phases (in a 240 volt phase to neutral system).

Hopefully, no hot swap PSU systems even exist where they allow AC mains voltages from separate PSU modules to be applied together anywhere, or if they do, are specifically designed to handle the worst case (e.g. at least 480 volts differential for PSUs that can operate at 100-240 volts). Common non-swappable PSUs for PCs only have DC and control lines that I have ever seen. But I can't get enough info on the hot swap type to rule out any phase-to-phase risks.

I am wanting to wire up servers which have 1+1 PSU redundancy (e.g. can run on 1 PSU being powered) to separate UPSes (small scale units, 1 or 2 per rack, not a giant room scale UPS). These UPSes would be wired to different phases in sequence. If I lose power to one phase only, and time passes by that exhausts the UPS battery, the phase diversity should still keep everything running (as long as the two remaining phases have that much capacity). Phase diversity UPSes would be nice, too, but I just don't see that on the market in rack size scales (3 to 6 kVA).

But in any case, what I am exploring at the moment is any possible cross phase risks, where phase to phase exceeds 240 volts, in the 1+1 redundant hot swap PSU system designs.
 
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