How the centrifugal start motor works. #1

This one covers the construction of the centrifugal start fan motor. This video is part of the heating and cooling series of training videos made to accompany my websites: www.graycoolingman.com and www.grayfurnaceman.com to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits.

[@mattee1433]

major thanks, this video helped me fix my older craftsman table saw, saving me a $250 motor. turned out all I had was a sawdust fouled centrifugal switch, which I learned the correct functioning of here.

[@grayfurnaceman]

Ahh, the old sawdust trick. Very common. GFM

[@Pretzel114]

Nice video GFM, always learn a lot from you. Thank you.

[@grayfurnaceman]

Welcome GFM

[@hvacrjunky6119]

Thanks for the lesson great video

[@pinaclesendas5015]

Thats a good description. I liked it.

[@marquitosmmrd]

The best and clear explanation

[@geojor]

thanks for this good info ...

[@Bass.Player]

I rarely see these but I have the occasion to hear them in operation on shut down when the plunger returns to the start position, it makes a single click sound as the rpm winds down...

[@wprv1]

The centrifugal switch removes the start coil from the circuit after the motor is up to speed. The start coil provides the necessary phase shift needed to get magnetic field rotating from a single phase supply. It is not used as the video suggests to get a fan with a higher inertia running. Inertial loads that keep the start coil in the circuit too long can damage motors utilizing centrifugal start switches. While motors such as cap-start or split-phase that use centrifugal start switches inherently have higher start torque than typical PSC motors, it is highly unlikely the reason they are used to start a blower or fan.

[@adeshmishra6060]

Awesome sir

[@mikumiku925]

Great info, Thank you for the video Sir~~ 😄

[@dcrams16]

Awesome

[@raulmurillo5171]

Thank you sir

[@piecetoyou8285]

Hi sir I taken a motor apart cleaned all up , It has a 3 leg type centrifugal and the two contacts are copper, It has no start capacitor and no run capacitor, When I switch it on at first I see a spark but runs fine, where the wire get connected to the motor from plug I see the spark there about, I have an earth wire from my on and off switch coming from my switch ,if I connect the earth wire from the off and on switch to ground the motor does not trip my house box , but if I remove the ground wire from going to earth on my bench it trips the house electric , So if I was to connect the motor to a machine body it will not trip the house electric, What are your thoughts on the spark on start up is this normal or could it be the copper contacts,

[@shimxininahi8024]

Tried to get the theory down. If centrifugal switch is open or no contact is made to the start capacitor circuit to the start winds, then the initial rotation will not happen or the spin will be slow.

[@grayfurnaceman]

Generally, the motor will not start unless there is a run cap. GFM

[@6lu5ky86]

Just want to remind viewers that dead center (starting from full stop) is not the same as frozen bearings (bearings that won't turn). If the bearings are frozen and the start winding is energized then they'll burn out because the rotor couldn't rotate to the appropriate rpm to disengage them.

[@littlefatzrow]

huh?

[@6lu5ky86]

+littlefatzrow It's all there man, you may have to look it up.

[@wufongtanwufong5579]

Sad fact: The centrifugal motor (There were centrifugal pumps. but not motors) was invented by an Australian Aboriginal who was given credit for the invention, but received no monies. Ironically. he is featured on the Australian $50 note.

[@shubhamburnwal4652]

What if we connect the starting winding to the motor in running condition ? Means if we connect the centrifugal switch permanently to the motor (any how). Please answer willing to know

[@grayfurnaceman]

If the start winding is connected to power continuously, the amperage draw will be excessively high and the start winding magnetic field will interfere with the main winding field. GFM

[@hardcorechicano]

I'm trying to get in the HVAC industry, I finished HVAC school but failed a interview yesterday because I forgot how to explain the centrifugal force and motor parts.....

[@grayfurnaceman]

I would find a centrifugal start motor, take it apart and seed how all the parts work. That usually will imprint it better on your mind. GFM

[@madisonelectronic]

Those run windings look a bit toasty.

[@vincentdinh190]

Where can I buy the switch kit? Thank you

[@grayfurnaceman]

They come connected to a new motor. GFM

[@Dime_Bar]

What's amp ridge?

[@grayfurnaceman]

Its amperage. The amount of current running thru the circuit. GFM