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View Full Version : Electrical problems with my lathe...again.



hornluv
10-10-2005, 03:13 PM
Hi Everyone,

I had some electrical problems several months ago and you were so kind as to help then. Well I need it again. Both of the contactors have gone out on my lathe and I've got new ones from Enco. The problem is, they've changed the parts they're using and the new ones aren't exactly like the old ones. The old ones have terminals that the new ones don't and vice versa. Here's a picture of the old one:

http://www.deharohorns.com/pictures/Parts/oldcontactor.jpg

And here's two of the new ones:

http://www.deharohorns.com/pictures/Parts/newcontactor1.jpg

http://www.deharohorns.com/pictures/Parts/newcontactor2.jpg

The terminals that are circled on the old one don't have corresponding ones on the new model. I'm wondering where I should put those wires. The terminals that are circled on the new contactor are not on the original, so maybe it is one of those? The wiring diagram for the lathe looks like it was drawn by a chimp, so that isn't much help. The bottom side of both contactors are pretty much mirror images of the tops.

Thanks in advance,
Stuart

ibewgypsie
10-10-2005, 10:04 PM
New one looks to be a relay, it has Normally open and normally closed contacts on there listed on the front.

not a direct interchange.

Where are you? I have some contactors (10hp) that look like the top one. Even have the auxillary contacts.

How are you running the lathe? 3 phase..??

If you are running 3 phase, the contactor can be used, after you take a meter and determine if the contacts are isolated front to rear, and proper contact arrangement.

It is soooo much easier when you get the right parts the first time. I had a supplier change plcs on me in mid job.. a $250,000 job.. new plcs did not work with the serial communications protocols and software I had wrote.. I was quite angry, like to have lost my shirt. Seems they *supply house" knew the other plc was due to be phased out and didn't tell me, but bought up all the old stock from other states to sell to me.

Those relays, they snap onto a din rail? it makes it easy to replace them.. take a screwdriver and find the lil button on the bottom pry it down and it unsnaps like your wifes bra..


OKAY<<< I looked again.. you have Line and neutral tags on the wires, I can only surmise it is single phase.. you are using two poles of the contactor.. The contacts on the front of the contacts are interlocks which stop the "other" coil from engergizing.. They loop the right through the left, when the right is in the left can not get power to the coil.. when the left is in the right can not get power.. Series the wires.. Now, on the other relay, you have Normally open contacts for the motor wires, and normally closed contacts for the interlocks.. You will have to of course pull most the jumpers off the top and discard them.. Now I am trying to figure out how they are switching capacitor poles to change directions? or is it a two speed contactor?

David

David

[This message has been edited by ibewgypsie (edited 10-10-2005).]

ibewgypsie
10-10-2005, 10:19 PM
"Drawn by a chimp" then translated by a spider monkeee.... HAA HAAA>. yeah.. I got some drawings here in my documentation notebooks that look like I had too many beers on that day.

I started using graph paper to keep the lines parallel fast, quick like.. and it lets me draw contacts the same size on each end of the paper..

If I had problems before, I'd look it over real well and figure out how it all works.. I'd not be tied to buying parts (the wrong ones) from just one supplier..

Six months ago, I throwed away two dozen contactors like the ones on the top. I installed about a dozen of them in one box, they all feed out from two inverters to plugs and machines all over the shop. A computer program decides which I am going to operate. Nothing complicated about that? huh? Just wait till the next guy buys or inherits the machines and tries to move them. HA.. I'll be laughing from my grave.. they all tie back to the bridgeports computer with communication cables. He'll go nuts if he don't get the whole shebang or only a part.. have to strip it all out and rewire.. Yeah, that rumbling laughter is from beyond the grave..
AND the software I wrote in visual basic.. nobody can follow my program logic.. Kinda introverted-extroverted notes about the weather on that day in the code, what my dog did to something?.. yeah..

Can you link to the previous posts? I can catch up maybe.. if it died so quick.. something is wrong..

sch
10-11-2005, 09:31 AM
The new contactors look just like the ones on most Chinese lathes sold lately. They are very simple devices with multipole single throw switches, some of which are NO and some
NC. When the relay is turned on the NO switches close and NC open. Not all switches will be used on any given contactor. The NO switches tend to be used as relay holding switches maintaining power until interrupted by one of the lathe control switches. Not much help there. You might find a much better wiring diagram by looking on the Grizzly site for lathes 'similar' to yours. There haven't been too many new ideas in simple 1ph lathe controls out of China in the last 30 yrs. Griz has PDF of many of their manuals on line and they are great manuals. It worked for me, the Griz manual for mine is much better: new typesetting, no line fade, easy to read designators.

Finally my lathe contactors are 24-28V coils, just like the Siemens you have pictured. The transformer that powers the contactors has secondary voltages of 0-6-32VAC. The 6v is just for the power lite bulbs. My contactors were driven off the 0 and 32Vac lines, I moved the connector for the contactor power from the 0 terminal to the 6v terminal thus dropping the contactor coil voltage to 26v.
As the bad contactor I had to replace was the main contactor that is on whenever the green lite is on it had overheated and had that hot electrics smell to it. I figured too much voltage and hope that the reduction will lengthen the lives of the remaining contactors. I looked for Siemens versions but ended up with Chinese knockoffs, about $35.
Steve

hornluv
10-11-2005, 10:30 AM
IBEW - It is single phase. I know absolutely nothing about electrical parts, so I didn't understand a thing you said, but thanks anyway. I'm in Illinois, BTW, but I think I'm going to figure out how to get these to work since I paid $79 a piece for them (grumble grumble). The jumpers that are on the new ones were ones that I moved over from the old ones before coming to the wires with no corresponding terminals.
Here's the original post from many moons ago:

http://bbs.homeshopmachinist.net//Forum1/HTML/010096.html

I just read over it and we're covering the same ground actually. Sorry for the repeat.
At the bottom I said that I got it working because it was wired a little off. I looked over the wiring diagram and the box and I noticed that a wire that needed to be on one terminal for 110 was on the terminal for 220. The guy that wired up the motor for me missed it. It worked for a while after that and then reverse went out again. Forward went out a couple of weeks ago. Now I have a 1200lb paperweight.

sch - I'll take a look at the Grizzly site. Thanks for the tip.

MTNGUN
10-11-2005, 11:18 AM
I burned up one of those things on my HF lathe before I dropped the voltage down as sch suggested. It seems to be a common problem.

You don't want to hear this, but the ideal way to solve the electrical problems on the chinese lathes is with a 3 ph. motor and VFD.

ibewgypsie
10-11-2005, 11:58 AM
American 3ph motor.. Japanese inverter.. A little harder to hook up, a lot harder to program by a novice.. If you purchase one, I suggest you get help or ship it by here or somewhere to get the numbers crunched in.

It works. DOn't throw lil slant eyed chips either. I found out at equipment auctions, they don't have a clue what a inverter is.. just make sure you don't end up with a 460 if you have 240 volts..

Contactor, relay..
Yeah, behind each vertical set of screws is a set of copper bars inside. They are on a bar that slides in and out with the magnetic coil. The bars either open or close according to the lil letters on the front, NC means Normally closed, opens when coil energized. NO means open, closes when energized.

NOW< with the new one, one set of the NC contacts are going to replace the lil contact block you circled on the top picture. THE jumpers will no longer work place to place like they did, since the normally open and closed are staggered on the new one.

Damn relay looks like hundreds of "one"s in a elevator, not a motor starter contactor.

Are you aware a simple drum switch can do the same thing, you toggle it one way, then the other to switch power or poles in the motor. I have one on my lathe (52 leblond). No coils, just a handle.

I just wish you guys with the problems lived closer. I could make it work in a bit, and then have some free beer and steaks.. WHOO HOO..

YOu need a small lighted probe, or a meter.. Need to learn the simple methods of testing continuity. (closed) circuits.. then read each pole of the contactor open and closed.. THEN learn to make a truth table, lil X for closed or O for open.. if contactor open then 1st contact is true top pole to bottom pole, does not connect to any other (NC), if open, top to bottom open, false (NO) but changes state when pushed in with a screwdriver to closed.. DO NOT push in while energized..

Learning can happen to all of us.. I am still learning every day. DOn't say "CAN't" or you "WON't" for sure.. of course, I am as stubborn as a mule..