I have an application where there can be considerable inductive flyback current into the supply rail, to raise it above the level naturally outputted by the AC-DC converter (48 V). Namely, the full rated output current (~10 A) can reappear as flyback current gradually decaying over up to several seconds.
We want to add some shunt OVP to the rail (a switching shunt regulator), but we are uncertain about a suitable trigger level for it. Namely, I am uncertain how to interpret the output OVP ratings for some supplies I consider. I already inquired with the manufacturer but got no answer so far.
A few short questions all related to the How? and Why? of the OVP:
If the output voltage is above the nominal 48 V, but below the values listed in the tables above, does that mean, that the PSU is still "on" but merely not switching anymore? Or at least that it has gone to its minimum possible duty cycle ? Surely the voltage feedback should force it into such a mode.
They both mention, that the output shuts down, when the OVP is reached. However, I can't imagine how this can possibly be any more "off" than situation (1.) above. The output rectifiers must withstand this voltage regardless of the input being on/off. And current will continue to flow into the output. So what is being shutdown and why?
Do the voltage ratings mean that the OVP trigger point can be between 48-60 V for the VMS-550C-48 and between 58.4-68 V for the RSP-500-75? At least the first one seems unlikely.
Does the description ("latching", "re-power to recover") mean that I have to cycle the input voltage for the supply to provide DC power again, once the OVP actually triggers? That would imply that our OVP shunt should limit the voltage to below the OVP trigger voltage.