48VDC is what telecoms kit and more importantly the old analogue phones ran on, so they had that with 110 or 240 AC being less available
Hence PSUs being designed for that
You should be able to replace with a standard AC PSU as I’m sure they didn’t have separate motherboards as they let the PSUs deal with the different voltages
Is your employer a Telco or similar?
48VDC is what telecoms kit and more importantly the old analogue phones ran on, so they had that with 110 or 240 AC being less available
Hence PSUs being designed for that
You should be able to replace with a standard AC PSU as I’m sure they didn’t have separate motherboards as they let the PSUs deal with the different voltages