Ignoramus10340 wrote:

Apparently, this SED2 drive has a very small capacitor compared to
other drives. Only 20 uF compared to 1,000 uF for other drives, with
the example of a 15 HP drive. (unspecified voltage)

That might, in my mind, account for voltage sagging when run from 1
phase, and low voltage delivered to motor.

So, a possibility to ponder would be to add some capacitance between
DC+ and DC-. The terminals are available for connecting, but I am not
sure of ramifications of, for example, inrush current greatly
increased.

Yes, this is a unit not designed for any holdup, and you have to add
a LOT of capacitance!

jon