Re: [Emc-users] Threading Hickups
On Thursday 18 October 2007, Kirk Wallace wrote: >On Thu, 2007-10-18 at 00:17 -0400, Jim Coleman wrote: >> On 10/18/07, Jon Elson <[EMAIL PROTECTED]> wrote: >> >> Kirk Wallace wrote: >> > Thanks again Jon and Chris. What should have been obvious >> >> turns > >... snip > >> interference sources like motor-VFD cables and any other that >> might have 120 or 240 VAC on them. >> >> Jon >> >> >> in my hitachi seiki manual, it says that twisted pair wire should be >> used for the encoders. not sure if this would help eliminate noise in >> your situation or not. > >I used the existing cable which has four shielded twisted pairs. I have >one pair for each A, B, I and power. How about the ends of the shielding wrap at the machine? They should be well grounded at the computer interface end and get as close as possible to the encoder, but should probably be isolated from the machine frame to avoid picking up noise or enabling a ground loop, which with variable phase angle thyristor speed controls on the spindle motor, can contain a lot of hf noises. And if the encoder has a ground, can it be isolated from the machine and tied to one of the shields? I'm thinking of the usual fiber or possibly nylon washers used for transistor isolation as a method of isolating the encoder pcb mounting from the machine frame. The mica sheets for such aren't all that thick if the washer thickness might be a problem in maintaining the spacings. A possible test to see if its VFD generated noise would be to see if it largely goes away when the motor is at full speed, and gets progressively worse as the speed is lowered. It may get better when the motor is at creep speeds too depending on how much losses there are mechanically, and the VFD itself. Some are thyristor based which would act like that, and some are basicly switching regulators driving dc motors, with the switching being done at several kilohertz. Those types could get noisier as the speed goes up, or if a hand is laid on the chuck to load the motor and make it work harder. Basically, look for a correlation between spindle speed and the extra noise pulses. An oscilloscope with at least a 20 megahertz bandwidth can be handier than bottled beer for this sort of troubleshooting. >> also what about an inductor or capacitor at the encoder in its power >> line to help smooth any noise introduced there? > >I have a short run between my encoder and a differential driver. I am >wondering about whether I should have some sort of filters on the high >impedance inputs of the driver. The thing is that with 50k pulses at >3,000 I'm not sure how much of a filter I could use. This might be a good place to use a piece of that shielded cable too. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If God had not given us sticky tape, it would have been necessary to invent it. - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Threading Hickups
On Wed, 2007-10-17 at 23:02 -0500, Jon Elson wrote: > Kirk Wallace wrote: > > Thanks again Jon and Chris. What should have been obvious turns out to ... snip > >trouble shooting for a while. > Check the grounding carefully. The best is to not have the > encoder grounded to the machine frame, but grounded through the > board reading the encoder signals. I have the shield of encoder cable tied to a central ground on the backplate that mounts all the left side electronics. > Shielding of the encoder > cables is almost always required. I used the existing shielded four pair. > Check the lay of probable > interference sources like motor-VFD cables and any other that > might have 120 or 240 VAC on them. I have a differential driver mounted next to the encoder, then the shielded cable to the receiver next to the UPC. About six inches away from the UPC are the two 100 Volt PWM amps. A little farther away are a bank of AC SSR's. I'll post some pictures soon. When I was getting index pulses without an encoder disk installed, I decided to disconnect the index connections to see when the noise stopped. The noise stopped as soon as I disconnected the encoder sensor. So either the noise is coming from the sensor, or having the sensor connected promotes the noise. I am going to have to give this some thought in order to plan the next move. > > Jon -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe Bridgeport mill conversion pending Zubal lathe conversion pending) - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Threading Hickups
On Thu, 2007-10-18 at 00:17 -0400, Jim Coleman wrote: > > On 10/18/07, Jon Elson <[EMAIL PROTECTED]> wrote: > Kirk Wallace wrote: > > Thanks again Jon and Chris. What should have been obvious > turns ... snip > interference sources like motor-VFD cables and any other that > might have 120 or 240 VAC on them. > > Jon > > > in my hitachi seiki manual, it says that twisted pair wire should be > used for the encoders. not sure if this would help eliminate noise in > your situation or not. I used the existing cable which has four shielded twisted pairs. I have one pair for each A, B, I and power. > also what about an inductor or capacitor at the encoder in its power > line to help smooth any noise introduced there? I have a short run between my encoder and a differential driver. I am wondering about whether I should have some sort of filters on the high impedance inputs of the driver. The thing is that with 50k pulses at 3,000 I'm not sure how much of a filter I could use. -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe Bridgeport mill conversion pending Zubal lathe conversion pending) - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] oversize transformer question
i was thinking the light bulb idea when i read it, i remember reading an article on a homebuilt 1000 watt audio amp, he did that because of the inrush current tripping a breaker. i was just wondering how many bulbs in parallel it would take to handle the current without blowing instantly? thinking of standard 100 watt incandescents. off topic, i bet that would look like a scene from an old horror movie when he turns it on haha. - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Threading Hickups
On 10/18/07, Jon Elson <[EMAIL PROTECTED]> wrote: > > Kirk Wallace wrote: > > Thanks again Jon and Chris. What should have been obvious turns out to > > be the problem. Graphing the encoder index shows random pulses mixed in > > with the regular pulses. I really did not want this to be the problem > > since I had already gone through fixing another issue with this encoder. > > I guess wishing is not a valid method for repairing machinery. > > > > Before, I had a problem with the encoder disk position coupled with a > > wobble. Now it seems to be an EMI problem because I get occasional index > > pulses with the disk removed and the spindle turning. I haven't been > > able to get a reliable reproduction of the fault, so I will be busy with > > trouble shooting for a while. > Check the grounding carefully. The best is to not have the > encoder grounded to the machine frame, but grounded through the > board reading the encoder signals. Shielding of the encoder > cables is almost always required. Check the lay of probable > interference sources like motor-VFD cables and any other that > might have 120 or 240 VAC on them. > > Jon in my hitachi seiki manual, it says that twisted pair wire should be used for the encoders. not sure if this would help eliminate noise in your situation or not. also what about an inductor or capacitor at the encoder in its power line to help smooth any noise introduced there? > - > This SF.net email is sponsored by: Splunk Inc. > Still grepping through log files to find problems? Stop. > Now Search log events and configuration files using AJAX and a browser. > Download your FREE copy of Splunk now >> http://get.splunk.com/ > ___ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Threading Hickups
Kirk Wallace wrote: > Thanks again Jon and Chris. What should have been obvious turns out to > be the problem. Graphing the encoder index shows random pulses mixed in > with the regular pulses. I really did not want this to be the problem > since I had already gone through fixing another issue with this encoder. > I guess wishing is not a valid method for repairing machinery. > > Before, I had a problem with the encoder disk position coupled with a > wobble. Now it seems to be an EMI problem because I get occasional index > pulses with the disk removed and the spindle turning. I haven't been > able to get a reliable reproduction of the fault, so I will be busy with > trouble shooting for a while. Check the grounding carefully. The best is to not have the encoder grounded to the machine frame, but grounded through the board reading the encoder signals. Shielding of the encoder cables is almost always required. Check the lay of probable interference sources like motor-VFD cables and any other that might have 120 or 240 VAC on them. Jon - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] oversize transformer question
Mark Pictor wrote: > I knew there would be inrush current to the capacitors, but I > didn't realize that the transformer, in and of itself, would have > an inrush current. Guess that shows how much I know! > Yup. It varies with the transformer design, and if you end up using a 240 V primary winding on 120 V, the "inrush" will be very small. What is going on is that the transformer integrates volts times time, and the iron in the core is designed to just handle the rated conditions, where the magnetic field builds in one half cycle, and is cancelled out in the next half-cycle. But, when you close the switch, the power line phase at that moment could be anything. If it happens to be right at the voltage zero crossing, then it gets a complete half cycle of the same polarity starting from zero magnetic field, and that saturates the core. The transformer will make a huge buzz for a half second, and the current will be enormous. > I was planning to use one or more motor run capacitors to limit > inrush current - use a relay in parallel with the cap, and close > the relay a few seconds after applying power. > This will kill your relay. Shorting a capacitor bank charged to 168 V peak will cause a minor explosion, and the L-C circuit will never settle. You need to use a low-value resistor, not capacitor, for this purpose. > Now that Jon brought it up, I think I will visit the local junkyard > instead. Depends entirely on the junkyard, of course, but almost any instance where old machinery is torn out of a plant, they get these transformers. Jon - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] EMC2 version on Live CD?
Thanks for the info Jeff. I have version 2.0.?? so I'll download a new CD and start over. My machine computer won't connect to the internet so I have to use another computer to put things on a CD to update anything. (This means taking my laptop to a wifi hot spot or borrowing a computer and connection.) Any way to determine the EMC2 version number before downloading the iso and loading it? Thanks, Clint > -- > > Message: 4 > Date: Wed, 17 Oct 2007 10:39:28 -0400 > From: xtra209 <[EMAIL PROTECTED]> > Subject: [Emc-users] EMC2 version on Live CD? > To: emc-users@lists.sourceforge.net > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Hi, > > Which version of EMC2 is on the Live Ubuntu CD? Where is the version > info available? I looked but could not find anything on this... > > Thanks, > > Clint > > > > -- > > Message: 5 > Date: Wed, 17 Oct 2007 10:51:09 -0500 > From: Jeff Epler <[EMAIL PROTECTED]> > Subject: Re: [Emc-users] EMC2 version on Live CD? > To: "Enhanced Machine Controller (EMC)" > > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=us-ascii > > The latest version of the Live CD includes either 2.1.6 or 2.1.7, I'm > not sure which. > > There are several ways to find the version of emc: > * If you use AXIS as your user interface, Help > About shows the version > number > * If you start emc from the terminal window, the version is printed > * If you issue the following command, you can see what version of the > package is installed: > dpkg -l emc2 > > Jeff > > > > -- - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Threading Hickups
Chris Radek wrote: >On Wed, Oct 17, 2007 at 12:35:12PM -0700, Kirk Wallace wrote: > > >>Previously, the dialog box would complain, but as soon as I got a valid >>number entered it would stop complaining. Now, as soon as the error >>message appears, it won't go away until I close the dialog box and start >>over. I have learned that in order to keep from getting an error >>message, I must keep an editable, but always valid number in the data >>entry box. Even deleting the initial 0.0 will toggle the error, so I end >>up clicking the end of the 0.0, back spacing ( 0.0| , 0.| , 0| ) to the >>zero and entering the required number such as 01.032. >> >> > >You are not the first one to say this! But, jeff and I have never >seen it and are baffled by the reports. Is there any pattern you >can see that would help us reproduce the problem? > > It doesn't fix the problem, but it may be easier to hit then -, then start typing. That will move to the beginning of the edit field and then select to the end of the field, so whatever you type replaces what's there. - Steve - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Threading Hickups
On Wed, Oct 17, 2007 at 12:35:12PM -0700, Kirk Wallace wrote: > > Previously, the dialog box would complain, but as soon as I got a valid > number entered it would stop complaining. Now, as soon as the error > message appears, it won't go away until I close the dialog box and start > over. I have learned that in order to keep from getting an error > message, I must keep an editable, but always valid number in the data > entry box. Even deleting the initial 0.0 will toggle the error, so I end > up clicking the end of the 0.0, back spacing ( 0.0| , 0.| , 0| ) to the > zero and entering the required number such as 01.032. You are not the first one to say this! But, jeff and I have never seen it and are baffled by the reports. Is there any pattern you can see that would help us reproduce the problem? Chris - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Threading Hickups
Thanks again Jon and Chris. What should have been obvious turns out to be the problem. Graphing the encoder index shows random pulses mixed in with the regular pulses. I really did not want this to be the problem since I had already gone through fixing another issue with this encoder. I guess wishing is not a valid method for repairing machinery. Before, I had a problem with the encoder disk position coupled with a wobble. Now it seems to be an EMI problem because I get occasional index pulses with the disk removed and the spindle turning. I haven't been able to get a reliable reproduction of the fault, so I will be busy with trouble shooting for a while. On Tue, 2007-10-16 at 21:06 -0500, Jon Elson wrote: > Kirk Wallace wrote: > > After having some success with my tuning, I went back to making threads > > without much success. Randomly, but close to every third or fourth pass ... snip > > I assume that the spike in the spindle velocity data is due to a counter > > reset at the start of each pass? > > > > Another problem, that I had read about a while back, cropped up too. > > When I invoke the touch-off dialog, I get a "Bad Number" error unless > > the first thing I do is forward arrow and leave at least the original > > leading zero in the data entry box. > The message just means whatever is in the box isn't valid - just > correct the characters in the box. For instance, "-" or "." are > invalid all by themselves, but "-.5" is OK. > > Jon Previously, the dialog box would complain, but as soon as I got a valid number entered it would stop complaining. Now, as soon as the error message appears, it won't go away until I close the dialog box and start over. I have learned that in order to keep from getting an error message, I must keep an editable, but always valid number in the data entry box. Even deleting the initial 0.0 will toggle the error, so I end up clicking the end of the 0.0, back spacing ( 0.0| , 0.| , 0| ) to the zero and entering the required number such as 01.032. -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe Bridgeport mill conversion pending Zubal lathe conversion pending) - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] oversize transformer question
At 01:17 PM 10/17/2007, you wrote: >I knew there would be inrush current to the capacitors, but I >didn't realize that the transformer, in and of itself, would have >an inrush current. Guess that shows how much I know! > >I was planning to use one or more motor run capacitors to limit >inrush current - use a relay in parallel with the cap, and close >the relay a few seconds after applying power. > >Now that Jon brought it up, I think I will visit the local junkyard >instead. > >Mark >--- John Kasunich <[EMAIL PROTECTED]> wrote: > > > Jon Elson wrote: > > > Mark Pictor wrote: > > >> 6.67kva 120v primary, 120v secondary > > > > > What the HE** do you need a 6.67 KVA transformer for? > > > > Mark already said that the transformers are at least twice as > > big has he really needs. > > > > But they are free (other than shipping), so he's asking us what > > "gotchas" there might be in using an oversize transformer. > > > > As long as there aren't any technical issues, an oversize but > > free part often beats a right-sized but expensive one. In this > > case however, I think inrush current is a significant technical > > issue. > > > > Regards, > > > > John Kasunich Put a light bulb in series with the primary. Flip the switch and the bulb flashes and gets dim as things charge up, then flip a second switch to short out the light bulb. __ Andre' B. Clear Lake, Wi. - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] oversize transformer question
I knew there would be inrush current to the capacitors, but I didn't realize that the transformer, in and of itself, would have an inrush current. Guess that shows how much I know! I was planning to use one or more motor run capacitors to limit inrush current - use a relay in parallel with the cap, and close the relay a few seconds after applying power. Now that Jon brought it up, I think I will visit the local junkyard instead. Mark --- John Kasunich <[EMAIL PROTECTED]> wrote: > Jon Elson wrote: > > Mark Pictor wrote: > >> 6.67kva 120v primary, 120v secondary > > > What the HE** do you need a 6.67 KVA transformer for? > > Mark already said that the transformers are at least twice as > big has he really needs. > > But they are free (other than shipping), so he's asking us what > "gotchas" there might be in using an oversize transformer. > > As long as there aren't any technical issues, an oversize but > free part often beats a right-sized but expensive one. In this > case however, I think inrush current is a significant technical > issue. > > Regards, > > John Kasunich - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] oversize transformer question
I don't have my figures, but I remember looking for a 3kva isolation transformer before. This is a little more than twice that size, as I mentioned in the OP. Now that I think about it, my 3kva figure was probably conservative. I hadn't thought of the scrap yard. That would probably be a lot cheaper. Mark --- Jon Elson <[EMAIL PROTECTED]> wrote: > What the HE** do you need a 6.67 KVA transformer for? This > can't be for a servo motor power supply unless you have a 50 > foot Kearney&Trecker bed mill. You should be able to find "step > down transformers" at the local scrap yard. You'll have to pay > scrap price for them, which is going up lately. These usually > can be set for 220 or 440 in, and 120 or 240 out. > > Jon > > - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] oversize transformer question
Jon Elson wrote: > Mark Pictor wrote: >> 6.67kva 120v primary, 120v secondary > What the HE** do you need a 6.67 KVA transformer for? Mark already said that the transformers are at least twice as big has he really needs. But they are free (other than shipping), so he's asking us what "gotchas" there might be in using an oversize transformer. As long as there aren't any technical issues, an oversize but free part often beats a right-sized but expensive one. In this case however, I think inrush current is a significant technical issue. Regards, John Kasunich - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] oversize transformer question
Mark Pictor wrote: > 6.67kva 120v primary, 120v secondary > I'd prefer 240v primary, but the nice thing about this one is that > it's cheap (aside from the shipping). I don't yet have the weight, > I am guessing from the weight of similarly-rated transformers. What the HE** do you need a 6.67 KVA transformer for? This can't be for a servo motor power supply unless you have a 50 foot Kearney&Trecker bed mill. You should be able to find "step down transformers" at the local scrap yard. You'll have to pay scrap price for them, which is going up lately. These usually can be set for 220 or 440 in, and 120 or 240 out. Jon - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] EMC2 version on Live CD?
The latest version of the Live CD includes either 2.1.6 or 2.1.7, I'm not sure which. There are several ways to find the version of emc: * If you use AXIS as your user interface, Help > About shows the version number * If you start emc from the terminal window, the version is printed * If you issue the following command, you can see what version of the package is installed: dpkg -l emc2 Jeff - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] EMC2 version on Live CD?
Hi, Which version of EMC2 is on the Live Ubuntu CD? Where is the version info available? I looked but could not find anything on this... Thanks, Clint - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] oversize transformer question
Mark Pictor wrote: > 6.67kva 120v primary, 120v secondary > I'd prefer 240v primary, but the nice thing about this one is that > it's cheap (aside from the shipping). I don't yet have the weight, > I am guessing from the weight of similarly-rated transformers. 6.67kVA at 120V is 55 amps. The inrush current is going to be fierce, probably 200-500A for the first couple of cycles. I agree that a 240V primary would be better. If I only needed a couple kVA, I would look for something that is a better fit to the application. Regards, John Kasunich - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] oversize transformer question
With the price of copper these days... I assume from shipping that this is copper and probably potted. Is this intended for isolation or what? Rayh On Wed, 17 Oct 2007 01:00:28 -0700 (PDT), "Enhanced Machine Controller (EMC)" said: >6.67kva 120v primary, 120v secondary >I'd prefer 240v primary, but the nice thing about this one is that >it's cheap (aside from the shipping). I don't yet have the weight, >I am guessing from the weight of similarly-rated transformers. > >He's got three, and he said they are free for pickup - but >California is a little far away to drive :) > >130 miles E of San Diego, if anyone nearby is interested - I can >put you in contact. > >Mark > >--- Jon Elson <[EMAIL PROTECTED]> wrote: > >> Mark Pictor wrote: >> > What are the drawbacks of an oversized transformer? Bulky, not >> as >> > efficient, ??? >> > >> > The one I am looking at is a little over 2 times the size I >> > guesstimated that I need. At $100+ for shipping, I'm not sure >> if >> > it's worth it or not. It would allow future expansion, but >> would >> > probably still be overkill. >> There are lots of transformers out there. I sure wouldn't pay >> $100 shipping for a transformer except in very special cases! >> There HAS to be a better deal somewhere, unless this is a 5+ KVA >> transformer, or you need it FedEx'ed next day. >> >> Jon >> >> >- >> This SF.net email is sponsored by: Splunk Inc. >> Still grepping through log files to find problems? Stop. >> Now Search log events and configuration files using AJAX and a >> browser. >> Download your FREE copy of Splunk now >> http://get.splunk.com/ >> ___ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > > >- >This SF.net email is sponsored by: Splunk Inc. >Still grepping through log files to find problems? Stop. >Now Search log events and configuration files using AJAX and a browser. >Download your FREE copy of Splunk now >> http://get.splunk.com/ >___ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users > > - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Emc-users Digest, Vol 18, Issue 40
Kirk, A friend of mine had the exact same problem with a brand new CNC lathe. He traced it to a bad spindle encoder cable. John On 17 Oct 2007 at 1:00, [EMAIL PROTECTED] wrote: > I went back to making threads > without much success. Randomly, but close to every third or fourth pass > comes out being about a half thread off. > > I assume that the spike in the spindle velocity data is due to a > counter reset at the start of each pass? > > Any help with these would be appreciated. > > -- > Kirk Wallace (California, USA - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] oversize transformer question
6.67kva 120v primary, 120v secondary I'd prefer 240v primary, but the nice thing about this one is that it's cheap (aside from the shipping). I don't yet have the weight, I am guessing from the weight of similarly-rated transformers. He's got three, and he said they are free for pickup - but California is a little far away to drive :) 130 miles E of San Diego, if anyone nearby is interested - I can put you in contact. Mark --- Jon Elson <[EMAIL PROTECTED]> wrote: > Mark Pictor wrote: > > What are the drawbacks of an oversized transformer? Bulky, not > as > > efficient, ??? > > > > The one I am looking at is a little over 2 times the size I > > guesstimated that I need. At $100+ for shipping, I'm not sure > if > > it's worth it or not. It would allow future expansion, but > would > > probably still be overkill. > There are lots of transformers out there. I sure wouldn't pay > $100 shipping for a transformer except in very special cases! > There HAS to be a better deal somewhere, unless this is a 5+ KVA > transformer, or you need it FedEx'ed next day. > > Jon > > - > This SF.net email is sponsored by: Splunk Inc. > Still grepping through log files to find problems? Stop. > Now Search log events and configuration files using AJAX and a > browser. > Download your FREE copy of Splunk now >> http://get.splunk.com/ > ___ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
