Electronics

What could be mean by “Fire Override (FOR) input” in a controller specifications?

Could this possibly be an input that over rides the fire condition?

in a controller specifications?

What controller, context is everything.

In the world of AC variable frequency drives used for HVAC applications, Fire Override instructs the drive to run ignoring all warnings and faults. Essentially it is a “run to destruction mode” used to clear smoke from a building that is on fire.

Your mileage may vary, depending upon the actual specification.

Fire modes are for use by the fire brigade and override everything else as they are used in emergency situations.

I suspect the fire officiers usually want to turn OFF all the fans to stop fire spreading, not “clear the smoke” (ie fan the flames)!!

Fireman’s override: https://library.e.abb.com/public/c4a86494826e4cfa970aff0b62c52c9b/No_21_firemans_override.pdf

MarkT:
I suspect the fire officiers usually want to turn OFF all the fans to stop fire spreading, not “clear the smoke” (ie fan the flames)!!

It’s the smoke that does most of the killing (no oxygen, toxic fumes, total disorientation so you can’t find your way out), not the flames. That’s why tunnels have those massive exhaust fans: to get rid of the smoke in case of a fire.

Clear the smoke, give people air to breath to stay alive and get out, when that’s done you can deal with the fire itself.

I don't think we are talking about a tunnel fire supression system in this thread, just an air conditioning system...

Of course - but the same problem: smoke kills, to increase survival rate of people inside the building you want to get rid of it. AC systems can help with this.