Inspection of the belated (delayed?) context, it's clear that "delayed" doesn't refer to the 300 VAC supply. It refers to the 16A fuse that protects the equipment (and the supply..).

Taking the 2nd example first:
supplied by a delayed fuse of 16 A
-->
alimentado via un fusible de fusión lenta de 16A

The first example is badly written in English, but it's still clear that "delayed" refers to the fuse.

So, what is a "delayed fuse"? It's a fuse that doesn't interrupt the supply as soon as an overload occurs. There is a delay - maybe a second or two - which avoids unnecessary loss of power if a very short overload occurs (eg: a short mains spike), but will still protect everything if the overload is longer (eg: a short-circuit).

Note that the Spanish translation corresponds to one of the alternative names of these fuses in English: "slow-blow".

Contrast and compare:
https://es.wikipedia.org/wiki/Fusible
Tipo gT: Fusible de fusión lenta. Protege contra sobrecargas sostenidas y cortocircuitos.

https://en.wikipedia.org/wiki/Fuse_(electrical)
The time delay fuse (also known as anti-surge, or slow-blow) are designed to allow a current which is above the rated value of the fuse to flow for a short period of time without the fuse blowing. These types of fuse are used on equipment such as motors, which can draw larger than normal currents for up to several seconds while coming up to speed.