wa8yxm wrote:
MEXICOWANDERER wrote:
Permanent magnet no brushes
That would be an oxymoron, PM motors ALWAYS have brushes.
This is not a PM motor.
It's brush less permanent mag. I have broken them open before. We would use 2 12 inch diameter fans like that to blow down on the batteries in electric fork trucks to aid in cooling. We used what they called Rapid Charge at 500 amps so there was always heat. The drivers didn't like hearing the fans so they would jab a pencil or plastic fork in them to stop them and usually you could remove it and they would take off. I know they dont like power washers. Many things like starter motors have permanent magnets and brushes.
At the end of my career we were working on electric fork lifts that ran a 48 volt 4500 pound battery powering a GE controller that changed dc to ac and ran a brushless 3 phase ac drive motor. It eliminated the high armature current draw when the drivers would try to bulldoze loads instead of lifting the load. More short cuts/more newspaper time.
On the dc drive trucks previous to that they ran brushes and excited the field with 10 gauge wire. 3/0 to the armature and 10 gauge to the field because the GE controller pulsed the field current, non series motor. Problem was that when stalled the armature amperage skyrocketed and would swell the armature resulting in raised commutator segments the brushes would click like crazy. It sucked bad changing 600 pound drive motors.
They were supposed to be an improvement over series dc motors powered by scr systems but the weakest link was the GE SEM separately Excited Motor controller. They were $1,700 and we had a couple pallets of them waiting to be shipped out all the time. Probably 30 per pallet. I referred to them as the $1,700 fuseable link.
That style fan is also available in ac brushless
