Why it is required to fuse each inverter in common dc bus

I have 4 vfd's in total supplied from one largest vfd in system. The other three vfd's don't have connection to ac grid. These 3 vfd's are supplied from common dc bus. I don't understand exact reason why I must fuse each inverter dc input. Some documents say it is done for protecting vfd against overloads and some documents say it is for protecting other vfd's in case of short-circuit that may happen in any vfd. Short circuit theory seems logical to me but I can't understand the one says it is against overload since vfd output already protect itself from overloads and there is no connection at the front end of these drives. What is meant by overload then (they are supplied by common dc bus only)
Is there anyone who has comment on it ?
Thanks in advance.

When you have a converter, or several converters, feeding a common DC bus, that converter capacity ends up being much larger than a single smaller drive connected to the bus. That means the DC bus capacitance is much higher as well and the potential for destructive energy on the smaller drive is disproportionate to what the components inside of the inverter section are designed to handle. The high speed semiconductor fuses are needed therefore to limit the potential destruction and resulting collateral damage should something go awry. You can do it without them, but if one small drive goes bad, it will likely take out EVERYTHING on that bus. Fuses are cheap insurance.