Hi,

So lets say the current is 50 /t but machine requires 100/t.

In said scenario the machine will simply void the incoming energy and do nothing.

Played in Manufactio.

What unit of power is involved, is it actually rf? That may be intentional.

What are you feeding in with?

Rf.
I am using immersive engineering cables.

Well, yes.
It'll input 50rf, nothing happens.
It'll input another 50rf, 100rf are supplied, machine does the 1st tick and consumes the 1st inputs & the associated energy cost.
It'll input 50rf, machine requires 100rf to continue the processing cycle. Not enough RF was supplied in time, reset the recipe tick time and wait until more energy has been provided.

Like 1.7 Gregtech machinery. This works as intended. Made to prevent cheesing higher tier recipes without having the power supply to back it up. Gregtech CE still works this way in 1.12 btw; except instead of losing all progress instantly, it'll lose 1% every 2 ticks or so. So, yea.