Thread: Motor running backwards?

Possibly not. I've seen the same thing happen with exhaust fans we use at work. If the start capacitor is on the way out and the motor gets a nudge in the wrong direction it will continue to run in the wrong direction. Your neighbour should be having trouble starting his saw though.

Maybe his elictricity account is overdue and the network is reposessing their power.

Reminds me of when I bought my Jet table-saw. When I fired it up it ran backwards. At least the supplier sent a sparky up the next day to rearrange the wiring.

Rocker

No this can happen The capacitor problem or another possibilty is the com the section the brushes ,if it is a brush motor, rests on needs cleaning as the grooves between the segments can clog up with carbon and cause this
A little crc spray often helps it would also indicate that the brushes are pretty worn
a good time to source new ones before they wear out completely




The trouble with life is there's no background music.

Tell him to take it to a motor repairer, its not worth #*@%ing around with, repair or replaicement is cheap considering the potential cost. My experience with motors is 15 yeras selling the rotten things for Brook Crompton, Toshiba and now AEG.

Regards

Phil Spencer

Now you've done it Phil, we'll be harrasing you with all sorts of electric motor type quizzes.
I'll think of some later ok

Originally Posted by E. maculata

Now you've done it Phil, we'll be harrasing you with all sorts of electric motor type quizzes.
I'll think of some later ok

I thought of a good question to ask, Bruce: "Can you get them for us cheap?"

Mick the eternal bargain hunter

That's a good start Mick, now Hi Ho away to all that cheap three phase gear I wanted buy and convert.

It sure can happen. Depending on the motor it can be a number of things. If you are comfortable with mechanical repairs then pull it apart and see what you find. Typically it will be the brushes/comutator requiring a clean, could be bearings that are worn (they stop the armature in the same place all the time).

If it's a prize piece of equipment then the repairman may be the answer if you can't work it out, if not then get yourself another one. I tend to buy quality and as such you can usually find spares and advice - the cheapies are a different story.

My 2p worth

Jamie

How about some 1HP 2 pole (2800 RPM) single phase flange mount for around $90.00 suit a small saw.

I can supply AEG single and three phase at a reasonable discount or a cost effective Chinese motor at better prices, the draw back is that I sell Industrial motors and they are all metric dimensions most machinery has imperial dimensions so you may have to redrill pulleys.

email me at [email protected]

Regards

Phil Spencer

To reverse an AC single phase motor reverse the connections on either the start or run windings. If it is a universal motor (Brushes) it could be the commutator. Either way DON'T stuff around with it unless you are an electrician or electricial engineer (you run the risk of discharging all the smoke and need a recharge its smoke that makes them run not electricity when the smoke comes out they don' run any more.), seriously if you don't know what you are doing you can end up pushing up dasies, and that means no more woodwork!

Regards

Phil Spencer

Phil, you can count on an email next time something motorised & electrical gets to smoking at my joint.







Bruce C
(the pun was fully intentional)

Originally Posted by E. maculata

That's a good start Mick, now Hi Ho away to all that cheap three phase gear I wanted buy and convert.

Retrofitted a three phase motor with an inverter to my Tough wood lathe about 6 years ago havn' changed a belt speed since the only way to turn. If you need some advice PM me

Regards

Phil Spencer

Hi All,


mmmmhhhhh let us see... mumble mumble mumble.........

If I well understood, the motor could be the type asynchronous monophase with the capacitor which serves for starting the run.
Normally, the electric windings are divided in two parts: one for the run and one for the starting the run.
Both are wired in one common point where usually is connected the neutral of the electric line and between the other two windings ends is put the capacitor.
The non neutral of the electric line is wired to the end of the run winding. Normally, the common point said above is achieved inside the motor, but if it's achieved externally and all windings ends with the two ends of the capacitor are put together in the connecting box, it's possible that one wiring bridge has loosen and thus the current flew in the wrong verse in the start winding.
This one has brought the motor to run in the opposite direction. When, that wiring bridge has become tightened, the motor has run in the correct direction again.
I council truly to make to control the motor to an expert or to try yourself to see if some bridge is loosen (if you are able):confused: .

However, an electric motor works on the principle that between two windings in which a current goes is created a force (force moment), which turns the machine. Alternatively one winding can be replaced with a permanent magnet which does the same as an electric winding. That moment force (couple) if the current direction is always the same, is always in the same direction. To change it you must invert the current direction of one winding.

I hope to be been quite clear.