Extra capacitor for switched PSU and G251's

[NiklasJ]

Hi,
this is my first post here, my name is Niklas and I am from Sweden -please excuse my english.
I'm in the process of converting a X1 mill to 4-axis cnc (will be 5-axis eventually)
I have bought some G251's and also a switched 48V/7+A PSU (might need to double up on PSU's when I get it all together and run 4- or 5-axis)
I plan on putting the PSU and the PC in a combined stand/cabinet below the mill and run wires (2.5mm2 or larger) from the PSU up to a box with the G251's, some gauges, limit inputs, switches etc placed up at the side of the z-axis column (about 1.5m wires from the PSU that split into 5 wires (for each gecko) when inside the box.
The 251s will be set at as close to 3.5A as I can to get the most torque (my motors should ideally have 4A wired bipolar parallell to get max tq)
I also plan to put fuses on each PSU+ input on the geckos, fast acting 4A fuses is about my only viable choice as it will be hard to locate anything closer to 3.5A locally (3.15A slow acting is avaiable but these would blow too quick I think)
Maybe it is useless having fuses if they dont blow just above 3.5A, I dont know?


Question:
Is there some advantage to be had by adding a extra capacitor across the PSU +/-? If so how large should it be for my setup that initially has 3 G251 operational and will eventually be 5 G251s -- considering that the 251s are equipped with capacitors as they come?
Should i put the capacitors at the PSU or at the "split point" inside the controller card box?

Best regards,

Niklas