electric motor forward/reverse wiring?

"DoN. Nichols" wrote

Huh, I was afraid i wouldn't. The link posted by Glenn...

Yeah, when I was trying to create a mental picture of what I needed I thought "triple pole dual throw" switch, and tried to find it on on-line (mcmaster.com, etc) and couldn't.

I think your ascii got scrambled up.

I'd think that would've been easier than all this hassle.

Huh. For me I'd think "intuitive" would be forward/right, reverse/left. (or maybe that's the way the lathe that i had used in the past was wired and got used to that.)

-snip-

I don't konw. Jim posted this link...

I do believe it can measure resistance, I don't know the terms, ohms, resistance, etc. I put it on the capacitor and it did what i read somewhere it would, pegged at one end of the scale and rapidly drop to near zero. It's an el-cheapo "Sperry", i stole it from Home Depot (i'm just kidding) (teasing Harold).

Huh. I was trying to find which one was the starting winding (i read the starting winding used thinner wire, trying to find which color wires went to the thin wires) but now I'm guessing the starting winding is obvious because it's the one with the capacitor and switch on it.)

OK, thanks.

oops.

Thanks. (Yeah, that's what i meant, 'C' and 'B'.)

Thanks. Yeah, this motor is w/o rubber bushing, my intent is to rigidly attach the switch to the headstock casting too.

Thanks again.

b.w.

According to William Wixon :

That will do it. :-) Was it the case of the switch, or the motor?

Well ... if you hadn't -- the motor would have kept starting. But *you* might have lit up. :-)

Hmm ... this suggests that one of the contacts in the drum switch may not be making reliable connection. The contact might be burned from tripping the breaker through it so many times, or it might have been loose all the time. Check it out by operating it with the cover off and watching the switch in low light. Look for sparking were one of the switch contacts closes. (You're more likely to see the sparking when it jerks, but maybe also when it starts right up. Look at the contacts and see whether they can be made to make better contact by something like cleaning the contacts with a points file (one design of switch), or squeezing the contacts together a bit (if it is like a wafer in a rotary switch from electronics.

I'll bet.

Nope -- The two run windings in series are acting as an autotransformer, dividing the voltage by two. But it is not a perfect division, so it is likely to show a slight bit of voltage. That is why I told you to not expect a perfect zero.

Also -- wires running adjacent to AC-powered lines pick up a bit of voltage from capacitive coupling -- if they are not connected to something which has low impedance to ground.

And even neutral typically has a bit of voltage referenced to ground, because some current is going through it, and its resistance is not zero, so there will be some voltage there as long as current is flowing through that neutral -- and that can even be from something else plugged into the same line.

The meter is floating, so no, there should be no problem. Now, if it were a scope probe, which has a ground clip which is truly normally connected to the power ground, you could have blown more breakers. :-)

So -- this time you were doing something only slightly wrong. :-)

Glad to help.

I hope that you get your switch working reliably -- as it

Enjoy, DoN.

According to William Wixon :

Hmm ... no -- I think that it is wiring of a double contactor to emulate that switching pattern.

Well ... the one on my Clausing is pretty much as yours is, but another which I have (of the sort which is used for the three-phase motor on a Bridgeport) is closer the kind shown in figures 5 through 8, and you can even see the cross-over wires if you look carefully. They are black insulated, and the switch body is a black plastic, so you don't see them at first glance.

That kind makes more sense to me -- because I don't have to analyze the wafers of the switch in the other to tell what it is doing.

They exist as toggle switches -- and even 4PDT -- but they aren't high enough current to reliably handle switching the motor live, only switching direction while it is stopped. And you would really want a 4PDTCO (Center Off) -- or you could not stop the motor.

I used a rotary switch designed for high currents -- gazillions of screw terminals.

I think that you were likely looking at it with a proportional pitch font -- which will scramble *any* drawing done in ASCII with a fixed-pitch font. And since different proportional pitch fonts are different widths for different characters, they don't all look the same, while a fixed pitch font, like Courier, will look the same on all machines. I see that there are some offsets put in by your quoting, so I'll fix them above, and you can try switching to Courier (or perhaps

There -- it is back as it should be for the moment.

Except that it doesn't have the right kind of handle to really

What are the labels on your drum switch? I'll bet left is forward, right is reverse.

The big problem is that it is showing three mechanically joined, but electrically independant single pole double throw center off switches. You can't do that with your drum switch, though I could with the extra which I have -- after cutting loose the crossover wires and replacing them in the right pattern.

The circuit which I provided would work with any drum switch designed for three-phase motor reversing.

Ohms are the units used to measure resistance.

Sperry should be a pretty good brand, actually.

Yes -- that is it.

O.K. That should do it.

Good Luck, DoN.