kitchen hood extractor (industrial)

[sparkydude]

Called out today to a commercial kitchen hood. Fan runs through a speed control DOL starter with overload and is interlinked to the gas proving unit.

Fan tripped out today and took a while to reset. The kitchen manager said that he managed to get it to start again but it will not run on speed 5 as it then trips the overload unit. Would i be right in thinking the fan needs an overhaul as it seems to be drawing too much current due to being caked in grease?
Could not gain access to fan as its on the roof and in the middle of a garden centre !! The motor was drawing 6.8A on speed 4 and the overload uit it runs through had a maximum of 9A which it was currently set at .

I am pretty sure it comes down to the fan needing to be cleaned , but welcome anyones oppinion It sort of confused me that the overload was set at full load as i thought normally you would install one with some tolerance in the scale.

Nick

 

[Paul.M]

Sparkydude I'm no expert on these matters and I hate motors but I have cone across this problem before. In my case it was a massive build up of grease on the fan blades putting a lot of weight on them therefore more torque on the rotor and the motor. My problem was with start up and the wrong type mcb but your situation sounds the same, clean it out and check your clamp meter results. Good luck.

 

[Knobhead]

All I can say is god help you. I’ve worked all my life in s**t and grime but only a couple of times on kitchen fans.

I can’t find the prayer for the dead at the moment, but I will be thinking of you.

Tools required
Hammer
Chisel
Paint scraper
Solvent spray
Full PPE
Fluoxetine helps as well!

 

[Knobhead]

OK joking aside you will find on the outer edges of the blades a build up of crud. Scrape that off, but this is where the fun come in. scrape 1 gram off one side and two grams off the other and the fan is out of balance! The building will be vibrating!
The best way is steam cleaning, if the motor will stand it.