Hi Daniel,
DC power supply is very common in substations due to reliability issues.
From our SMB appliances just the 1200R support DC power supply, as it is the only appliance designed for industrial applications. Currently 1200R support just 12-72VDC.
In case you have requests to support 125VDC, I highly recommend to open a RFE with solution center concerning the issue. The issue will be evaluated according to the commercial opportunity and as substations are a large market also outside of the USA, I really hope the appliance will be modified.
For the time, it is important not to lose the opportunities and we can offer the 1200R with industrial DC to DC converters.