Thread: Variable speed control.

Ok, I know nada about ac , dc and such so . Looks like its getting complicated for me . So , I am not sure if i am supposed to be encouraged by your response ? Are you saying , yes , you can use the variable control with this variable dc thing to make it all work and save money in the long run ?

Well, DC motors and controls like this are quite expensive I am certain. To save money and get it done simply, an interchangable pulley setup to change speeds and a regular,common AC motor would be the way to go, I expect. This setup was salvaged by a friend and given to me and it works. In that regard, it is more efficient for me to use it. Otherwise, I would be going with the former!

What I believe to be true from asking a billion times is,,,

Direct Current motors can be variable. As said , it is because they are made to handle all levels of current on the inside. If the horse power is too low, then you may loose the torque needed to do the work at lower speeds.

Alternating Current motors are made to handle 1 level of current on the inside. Changing that level creates heat in the motor. Enough heat to melt copper :<0)

Originally Posted by 10Pups

What I believe to be true from asking a billion times is,,,

Direct Current motors can be variable. As said , it is because they are made to handle all levels of current on the inside. If the horse power is too low, then you may loose the torque needed to do the work at lower speeds.

Alternating Current motors are made to handle 1 level of current on the inside. Changing that level creates heat in the motor. Enough heat to melt copper :<0)

Well-said, Pups!

Mine is AC and is variable speed...

Originally Posted by shooter74743

Mine is AC and is variable speed...

Yes, this DC motor setup runs on AC current as well. I expect an AC motor which is variable has many differences than one which is a single speed. Brother-in -law will know. I shall ask!

Keep in mind that my motor is 3 phase though...

Originally Posted by sharptonn

Yes, this DC motor setup runs on AC current as well. I expect an AC motor which is variable has many differences than one which is a single speed. Brother-in -law will know. I shall ask!

No. A variable speed AC motor and a fixed speed AC motor are the same. The difference is the drive needed.
AC engines are controlled by changing the frequency of the input signal. For this, a frequency convertor is needed, and decent ones cost money. Sometimes as much or more than the motor itself.

Got TWO 1HP DC motors in my shop and no controller. :/ Found one on craigslist the other day for $200...... It was more than I needed as it had a tach and some other crud I don't need for a belt grinder so I passed.

Tom, my motors came off bulk mail machines. Probably the same as the ones you refer to.

I have a similar lesson drive controlling a variable speed sander I built.
The input plugs into your wall @ 110 vac.
The output will drive either a 90, or 180 vdc motor. You can wire the output either way as its a two wire output plus ground set up. It will run both directions depending on how you wire it, white to white, or white to black wire.
You can get a used dc motor all over, just find the hp, and shaft size you want and you can build from there. Lots of threads from folks on ideas and such.
Just need to verify input and output connections by removing the cover. Make sure any jumpers are set to the desired voltages and voila.. Now, if you are not comfortable wiring a household lamp, get a bud to help. Ideally with a multi meter to verify everything before you connect your motor.
Cheers.