Simple Fan Speed Controller
Simple Fan Speed Controller
(OP)
Here is my situation. I have a very small VFD(2hp) housed in a very large enclosure(standard Square D issue) next to a conference room. The enclosure has a muffin fan that is very loud. I want to reduce the speed of the cooling fan, since the drive enclosure is in an air conditioned room anyway. The fan is 120VAC and draws about 35 watts. I want to select a rheostat type controller that would allow me to drop the fan speed to the point where the noise is much less obtrusive.
I tried a controller I had laying around and it worked somewhat, but not very well. it only changes the speed by 15% or so. Is there a way to select a specific rating rheostat type controller that would be able to slow the fan down further, or is that more a function of the fan motor itself.
I tried a controller I had laying around and it worked somewhat, but not very well. it only changes the speed by 15% or so. Is there a way to select a specific rating rheostat type controller that would be able to slow the fan down further, or is that more a function of the fan motor itself.





RE: Simple Fan Speed Controller
RE: Simple Fan Speed Controller
RE: Simple Fan Speed Controller
http://www.digikey.com/product-detail/en/5915PC-12...
RE: Simple Fan Speed Controller
RE: Simple Fan Speed Controller
You can use a small autotransformer to reduce the voltage, or just replace it with a less powerful fan. You can almost certainly find one with the same diameter but reduced airflow, for example 5915PC-12T-B10-A00 has about half the airflow of the one you currently have and is the same frame size.
RE: Simple Fan Speed Controller
Thanks to all for the input.
RE: Simple Fan Speed Controller
I think that the air flow is generating most of the noise, so you can try to reduce it with a simple damper - preferably made from cloth/fabric bag that you put some cotton or other fibre into.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Simple Fan Speed Controller
The two-pole fire siren muffin fans are usually bought by people looking for maximum airflow above all else. Said people don't have to sit next to the fans, ever.
Mike Halloran
Pembroke Pines, FL, USA
RE: Simple Fan Speed Controller
What people usually do in similar situations is to duct clean cool air into the box from a location where there is enough static pressure to ensure suitable air flow without a fan. So to accomplish that, you must calculate the minimum airflow required in that box for the worst case scenario of the VFD heat output. The safe bet if you do not know the heat rejection of the VFD is to assume 95% efficiency, meaning 5% of the kW going into the VFD will be rejected as heat into the box. Most are better than that, but none are better than 97% efficient (even the ones who claim 98% are usually spinning the truth). Once you know the heat rejection (including all OTHER devices in that box), you can get one of several on-line fan calculators to tell you how much airflow you will need at the ambient air temperature to maintain the maximum operating temperature of that drive (usually 40C) safely.
"Will work for (the memory of) salami"