Date: Fri, 08 Dec 1995 10:17:02 -0700 From: mscalora@itsnet.com (Mike Scalora) Organization: Novell Mime-Version: 1.0 To: mscalora@itsnet.com (Mike Scalora) Subject: [HOWTO] [Fwd: Re: Reversing motor direction] Status: RO From: joseph.mendum@tcs.wap.org (Jos. H. Mendum) Newsgroups: rec.woodworking,rec.crafts.metalworking Subject: Re: Reversing motor direction Date: Wed, 06 Dec 1995 22:43:54 -0500 Organization: Washingon Apple Pi user group in Washington, D.C. Lines: 68 Message-ID: References: <4a4789$184g@watnews2.watson.ibm.com> NNTP-Posting-Host: dialup10.wap.org Path: gronk.provo.novell.com!grok.provo.novell.com!nntp.et.byu.edu!news.kei.com!newsfeed.internetmci.com!in2.uu.net!news.cais.net!news.his.com!dialup17.wap.org!user Xref: gronk.provo.novell.com rec.woodworking:94520 rec.crafts.metalworking:20000 In article , vincent.j.miller.4@nd.edu (Vince Miller) wrote: >In article <4a4789$184g@watnews2.watson.ibm.com> rhoover@shimano.watson.ibm.com (Roger Hoover) writes: >>- If I trace the wires back to the coils and starting capacitor, >>are there general principles that work for all motors? >That's a great question. >I also would like to know about puting a starting cap on a split phase motor I'm using for a lathe. Should I? Can I? >These two books have been recomended: >_How Elect Motors Start and Run_ Parady and Turner _Electric Motors_ James Allison >Are they ok, are there better sources? >Vince I have Veinott's "Fractional- & Subfractional-Horsepower Electric Motors" (1970), but the truth is it's not a lot of help for changing connections on specific motors. I don't think I've ever found a motor I was working on listed. (This is not to say that it isn't just dandy for principles!) Tracing the wires back, and knowing what to look for, is the only way to go. So here's a shot at what to look for: A single-phase induction motor (and I assume that's what we're talking about here) has a starting winding and a running winding, the former being cut out by some kind of switch when the rotor gets up to speed. First clue: If a winding is hard-wired to the switch, it's the starting winding. (Capacitor-start motors also have a capacitor in series with the switch and starting winding.) Basicly, one end of the running winding and one end of the starting winding/cap/switch leg are connected to one side of the line, and the other ends of both are connected to the other side of the line. Reverse the direction of rotation by interchanging the connections to the line of the starting leg ONLY. Dual-voltage (110-220) motors have the running winding split into two pieces, which are connected in parallel for 110 volts and in series for 220 volts. Starting windings seem usually to be (according to Veinott's book) 110 volt, so at 220 volts they are connected in parallel with one of the running windings and in series with the other. But reversing the direction of rotation is done the same way: Leaving all other connections as is, exchange the starting leg ends. Unfortunately it's not at all that simple, because all self-respecting motors come with some kind of thermal protection gadget from which the maker's name and model number have long since rubbed off; there are just three terminals with wires soldered on. How these gadgets are to be connected depends, and I hope someone else can provide some info on that. The last time I had to deal with one I cheated: I called the manufacturer, did what he said, and started the motor up from across the room. With regard to Vince's question about adding a capacitor to a split phase motor, I'd say of course you can, but I don't think you should. If you want a motor with different characteristics, buy one designed that way. New motors aren't that expensive, and used motors are (or were the last time I bought one) really cheap. Regards, jhm