The interest of this assembly before the power supply

[Bill]

Hello everyone,

I have just noticed that there is an assembly installed before each power supply unit, I would like to know why ? what is the point of this assembly ? and why the one framed in red has a breaker and the other does not, what is the difference between them ?

Thank you so much !!

[AVGresponding]

The purpose of the "no fuse breaker", and "NF", are to isolate the unit from the supply so that it can be safely worked on.