Re: [Emc-users] VFD causing limits to trip. Huh?
On 03/16/2015 09:40 PM, Karlsson Wang wrote: A shield is primarily intended to prevent electrostatic coupling from the outside world. So by grounding in the consuming end the shield will get the ground potential of the consumer and the signal cables will be shielded from different external electric fields. This should motivate why as you say the shield should be connected in this end only. If there are current there is also a potential difference. There are generally three cases to consider: 1) a shield as a Faraday cage; this means that only one side of the shield may be connected to go into the earth/ground star-point where you maintain an absolute reference of zero (0V). The shield is used to dump all (most) cable-internal EM radiation into a low-impedance star-point via the shield. 2) a shield as in a coaxial conductor; here the signal is contained in the cable and the shield is part of the conducting circuit. This works on basis of very tightly controlled cable properties and is generally limited to a specific frequency range per cable specs. 3) all other cases; the shield is connected at both sides and is intentionally or unintentionally part of the conducting circuit. This case will generally give you worse results in terms of EMI emissions and protection. The shield will radiate and may act as an antenna to worsen the situation. I consider the VFD to be a noise source since it have common mode voltage which will emit an electrical field. There is also a capacitance between the VFD cables and shield. Since Shield impedance on high frequency is far from zero the shield around the VFD cables will not be at GND potential. The most common method is to increase common mode inductance by a filter but I have also seen active filters which reduce the common mode voltage and multiple step voltage inverters. With respect to VFD systems; the amount of junk they produce depends on the quality of the converter. The best version generates a relatively pure sinusoidal output and the EMI it generates is very minimal. Such VFD can normally be connected without problem with unshielded cabling. The lesser quality emulates a sinusoidal output, but has substantial higher harmonics. These VFDs are not too shabby, but they can cause interference. The best solution is to filter the output before putting it on (long) cables. No shielding is required when the harmonics are under control, but it generally does not hurt to use a Faraday cage type shield. The cheap VFDs are poor substitutes and generate nearing square-wave output. The amount of EMI from higher harmonics is high and is often difficult to filter at the source. These VFDs should be used with both output filters and shielded cabling. The remaining problem that may arise is EMI from the motor. The remaining harmonics may radiate from the motor just as easily. That cannot be solved with shielding of the cables. You must ensure proper earthing of the motor as well and it should be enclosed in a proper metal casing. It should also be noted that VFD frequency changes cause harmonics in the output. If you turn on/off the hard way, then you can introduce some transients that are very hard to control. The best way is to control the up-/down-going frequency such that no abrupt changes can occur and therefore no transients are allowed to be created due to too fast changes. -- Greetings Bertho (disclaimers are disclaimed) -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] DIY CNC MILL LATHE
Good day, Thanks for the effort to show your excellent DIY lathe/grinder. cheers john -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] VFD causing limits to trip. Huh?
I would recommend that shielded signal cables have the shield grounded only at the end where the signals are consumed. If a ground is needed by the device at the end of the cable, you should use a conductor inside rather than the shield itself. If there are signals going both ways, provide the shield ground connection at the end where the most sensitive signals are consumed. The purpose of grounding only one end of the shield is to prevent current from flowing in the shield itself and distorting the signals due to electromagnetic coupling. A shield is primarily intended to prevent electrostatic coupling from the outside world. If the cable does not contain sensitive signals, such as the power cable from a VFD to the spindle, then it is acceptable to ground both ends of the shield. Steve Stallings www.PMDX.com -Original Message- From: Matt Tucci [mailto:matt2c1...@gmail.com] Sent: Monday, March 16, 2015 7:54 AM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] VFD causing limits to trip. Huh? Are the shielded wires only grounded at one end and at the controller end? On Sun, Mar 15, 2015 at 1:22 PM, Karlsson Wang nicklas.karls...@karlssonwang.se wrote: I think grounding is the most important. There are normally a common mode voltage at the inverter output to motor so the inverter power ground will bounce around each time inverter is switched. If this bouncing is coupled to the logic ground there may be a lot of problems. Nicklas Karlsson On Sun, 15 Mar 2015 14:39:24 + (GMT) russ...@lls.lls.com (Russell Brown) wrote: I promised to report back so... I fitted the filter (Schaffner FN2030 Series 16A 250 V ac 400Hz) on the VFD mains input and that did make a difference. My failing case job ran 70% of the way through where without it the job failed 10% in. Not the complete solution though. I then tried a ferrite core (mains clipon stylee) on the input of the field power supply. No difference. A ferrite core (ring with both wires looped through it a couple of times) on the output of the 12V field power made no difference either. A ferrite core (ring as above) on the limit switch wires fitted at the Mesa end made no difference either. So... finally I replaced the limit switch wires with shielded cable (grounded only at the Mesa end). That seemed to do the final trick and the job ran all the way through. Of course I don't know if this is a 100% fix or just enough to get through my failing case (other jobs without all the above have run fine). I guess time will tell. Hope that's useful for someone. -- Regards, Russell | Russell Brown | MAIL: russ...@lls.com PHONE: 01780 471800 | | Lady Lodge Systems | WWW Work: http://www.lls.com | | Peterborough, England | WWW Play: http://www.ruffle.me.uk | -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net
Re: [Emc-users] VFD causing limits to trip. Huh?
Are the shielded wires only grounded at one end and at the controller end? On Sun, Mar 15, 2015 at 1:22 PM, Karlsson Wang nicklas.karls...@karlssonwang.se wrote: I think grounding is the most important. There are normally a common mode voltage at the inverter output to motor so the inverter power ground will bounce around each time inverter is switched. If this bouncing is coupled to the logic ground there may be a lot of problems. Nicklas Karlsson On Sun, 15 Mar 2015 14:39:24 + (GMT) russ...@lls.lls.com (Russell Brown) wrote: I promised to report back so... I fitted the filter (Schaffner FN2030 Series 16A 250 V ac 400Hz) on the VFD mains input and that did make a difference. My failing case job ran 70% of the way through where without it the job failed 10% in. Not the complete solution though. I then tried a ferrite core (mains clipon stylee) on the input of the field power supply. No difference. A ferrite core (ring with both wires looped through it a couple of times) on the output of the 12V field power made no difference either. A ferrite core (ring as above) on the limit switch wires fitted at the Mesa end made no difference either. So... finally I replaced the limit switch wires with shielded cable (grounded only at the Mesa end). That seemed to do the final trick and the job ran all the way through. Of course I don't know if this is a 100% fix or just enough to get through my failing case (other jobs without all the above have run fine). I guess time will tell. Hope that's useful for someone. -- Regards, Russell | Russell Brown | MAIL: russ...@lls.com PHONE: 01780 471800 | | Lady Lodge Systems | WWW Work: http://www.lls.com | | Peterborough, England | WWW Play: http://www.ruffle.me.uk | -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Mesa 7i8- hal load string
On Mon, 16 Mar 2015, Marius Liebenberg wrote: Date: Mon, 16 Mar 2015 07:19:38 + From: Marius Liebenberg mar...@mastercut.co.za To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: [Emc-users] Mesa 7i8- hal load string Hi I am looking for an example of the load string in the hal file for the 7i80. I have done as the manual directed but I am not sure if it is correct. [HOSTMOT2] DRIVER=hm2_eth board_ip=10.10.10.10 BOARD=7i80 CONFIG=num_encoders=1 num_stepgens=5 sserial_port_0=20xx I still cannot get the 7i80 to communicate with the hm2 driver. The board mac is read but there it ends. - Regards / Groete Marius D. Liebenberg +27 82 698 3251 +27 12 746 6064 -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] VFD causing limits to trip. Huh?
Steve, this is a good description of noise reduction by shielding. To make it more exact, the shield should be grounded at the end where the lower impedance is, mostly the signal source. And not using the shield as a conductor is useful because any current flow in the shield would cause magnetic noise to be induced in the conductors along inside the cable. Even in power cables, grounding both ends of the shield may cause ground loops,resulting in mains frequency currents (formerly: hum) that are hard to locate. Generally, magnetic noise is harder to fight than electrostatic. Peter Am 16.03.2015 15:41, schrieb Steve Stallings: I would recommend that shielded signal cables have the shield grounded only at the end where the signals are consumed. If a ground is needed by the device at the end of the cable, you should use a conductor inside rather than the shield itself. If there are signals going both ways, provide the shield ground connection at the end where the most sensitive signals are consumed. The purpose of grounding only one end of the shield is to prevent current from flowing in the shield itself and distorting the signals due to electromagnetic coupling. A shield is primarily intended to prevent electrostatic coupling from the outside world. If the cable does not contain sensitive signals, such as the power cable from a VFD to the spindle, then it is acceptable to ground both ends of the shield. Steve Stallings www.PMDX.com -Original Message- From: Matt Tucci [mailto:matt2c1...@gmail.com] Sent: Monday, March 16, 2015 7:54 AM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] VFD causing limits to trip. Huh? Are the shielded wires only grounded at one end and at the controller end? On Sun, Mar 15, 2015 at 1:22 PM, Karlsson Wang nicklas.karls...@karlssonwang.se wrote: I think grounding is the most important. There are normally --- Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft. http://www.avast.com -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Mesa 7i8- hal load string
I got that one right but was wondering about the config string of hm2 -- Original Message -- From: andy pugh bodge...@gmail.com To: Marius Liebenberg mar...@mastercut.co.za; Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: 2015-03-16 18:39:10 Subject: Re: [Emc-users] Mesa 7i8- hal load string On 16 March 2015 at 16:23, Marius Liebenberg mar...@mastercut.co.za wrote: Thanks Peter that is a good start. Is the order of invocation in the hal file important. Yes. It is very important to loadrt hostmot before you loadrt hm2_eth -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Mesa 7i8- hal load string
On Mon, 16 Mar 2015, Marius Liebenberg wrote: Date: Mon, 16 Mar 2015 16:23:18 + From: Marius Liebenberg mar...@mastercut.co.za To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Mesa 7i8- hal load string Thanks Peter that is a good start. Is the order of invocation in the hal file important. Maybe give me an example as well. Sorry man I am plucking at straws here as I am at my wits end with stuff I know nothing about :) The hal files are pretty much identical to hm2 hal files for PCI or EPP cards with the exception of the different driver name and added ip address token on the driver command line Here's an example hal/ini file set for a 7I92 freeby.mesanet.com/7i92step.zip -- Original Message -- From: Peter C. Wallace p...@mesanet.com To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: 2015-03-16 16:53:07 Subject: Re: [Emc-users] Mesa 7i8- hal load string On Mon, 16 Mar 2015, Marius Liebenberg wrote: Date: Mon, 16 Mar 2015 07:19:38 + From: Marius Liebenberg mar...@mastercut.co.za To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: [Emc-users] Mesa 7i8- hal load string Hi I am looking for an example of the load string in the hal file for the 7i80. I have done as the manual directed but I am not sure if it is correct. [HOSTMOT2] DRIVER=hm2_eth board_ip=10.10.10.10 BOARD=7i80 CONFIG=num_encoders=1 num_stepgens=5 sserial_port_0=20xx I still cannot get the 7i80 to communicate with the hm2 driver. The board mac is read but there it ends. - Regards / Groete Marius D. Liebenberg +27 82 698 3251 +27 12 746 6064 -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Mesa 7i8- hal load string
On 16 March 2015 at 16:23, Marius Liebenberg mar...@mastercut.co.za wrote: Maybe give me an example as well. Sorry man I am plucking at straws here as I am at my wits end with stuff I know nothing about :) Have you read the documentation? http://www.linuxcnc.org/docs/devel/html/drivers/hostmot2.html Admittedly it seems to know nothing at all about hm2_eth or hm2_spi, but those are in the same class of sub-driver as hm2_pci and hm2_7i43 (the latter of which may soon be hm2_epp) -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Mesa 7i8- hal load string
Thanks Peter that is a good start. Is the order of invocation in the hal file important. Maybe give me an example as well. Sorry man I am plucking at straws here as I am at my wits end with stuff I know nothing about :) -- Original Message -- From: Peter C. Wallace p...@mesanet.com To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: 2015-03-16 16:53:07 Subject: Re: [Emc-users] Mesa 7i8- hal load string On Mon, 16 Mar 2015, Marius Liebenberg wrote: Date: Mon, 16 Mar 2015 07:19:38 + From: Marius Liebenberg mar...@mastercut.co.za To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: [Emc-users] Mesa 7i8- hal load string Hi I am looking for an example of the load string in the hal file for the 7i80. I have done as the manual directed but I am not sure if it is correct. [HOSTMOT2] DRIVER=hm2_eth board_ip=10.10.10.10 BOARD=7i80 CONFIG=num_encoders=1 num_stepgens=5 sserial_port_0=20xx I still cannot get the 7i80 to communicate with the hm2 driver. The board mac is read but there it ends. - Regards / Groete Marius D. Liebenberg +27 82 698 3251 +27 12 746 6064 -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Mesa 7i8- hal load string
On 16 March 2015 at 16:23, Marius Liebenberg mar...@mastercut.co.za wrote: Thanks Peter that is a good start. Is the order of invocation in the hal file important. Yes. It is very important to loadrt hostmot before you loadrt hm2_eth -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Mesa 7i8- hal load string
-- Original Message -- From: andy pugh bodge...@gmail.com To: Marius Liebenberg mar...@mastercut.co.za; Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: 2015-03-16 18:42:15 Subject: Re: [Emc-users] Mesa 7i8- hal load string On 16 March 2015 at 16:23, Marius Liebenberg mar...@mastercut.co.za wrote: Maybe give me an example as well. Sorry man I am plucking at straws here as I am at my wits end with stuff I know nothing about :) Have you read the documentation? http://www.linuxcnc.org/docs/devel/html/drivers/hostmot2.html From top to bottom and back several times Admittedly it seems to know nothing at all about hm2_eth or hm2_spi, but those are in the same class of sub-driver as hm2_pci and hm2_7i43 (the latter of which may soon be hm2_epp) -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] VFD causing limits to trip. Huh?
The frequency converters I have seen for electric motors generate a square wave voltage. To generate a sinus the duty cycle is varied to get sinus voltage in average and usually the current is close to sinus. Then it come to quality I guess the large difference is in filters and coupling to control signal ground. There exist true sinus output but I think all of them are sold as true sinus for a higher price. Nicklas Karlsson On Mon, 16 Mar 2015 22:19:42 +0100 Bertho Stultiens ber...@vagrearg.org wrote: On 03/16/2015 09:40 PM, Karlsson Wang wrote: A shield is primarily intended to prevent electrostatic coupling from the outside world. So by grounding in the consuming end the shield will get the ground potential of the consumer and the signal cables will be shielded from different external electric fields. This should motivate why as you say the shield should be connected in this end only. If there are current there is also a potential difference. There are generally three cases to consider: 1) a shield as a Faraday cage; this means that only one side of the shield may be connected to go into the earth/ground star-point where you maintain an absolute reference of zero (0V). The shield is used to dump all (most) cable-internal EM radiation into a low-impedance star-point via the shield. 2) a shield as in a coaxial conductor; here the signal is contained in the cable and the shield is part of the conducting circuit. This works on basis of very tightly controlled cable properties and is generally limited to a specific frequency range per cable specs. 3) all other cases; the shield is connected at both sides and is intentionally or unintentionally part of the conducting circuit. This case will generally give you worse results in terms of EMI emissions and protection. The shield will radiate and may act as an antenna to worsen the situation. I consider the VFD to be a noise source since it have common mode voltage which will emit an electrical field. There is also a capacitance between the VFD cables and shield. Since Shield impedance on high frequency is far from zero the shield around the VFD cables will not be at GND potential. The most common method is to increase common mode inductance by a filter but I have also seen active filters which reduce the common mode voltage and multiple step voltage inverters. With respect to VFD systems; the amount of junk they produce depends on the quality of the converter. The best version generates a relatively pure sinusoidal output and the EMI it generates is very minimal. Such VFD can normally be connected without problem with unshielded cabling. The lesser quality emulates a sinusoidal output, but has substantial higher harmonics. These VFDs are not too shabby, but they can cause interference. The best solution is to filter the output before putting it on (long) cables. No shielding is required when the harmonics are under control, but it generally does not hurt to use a Faraday cage type shield. The cheap VFDs are poor substitutes and generate nearing square-wave output. The amount of EMI from higher harmonics is high and is often difficult to filter at the source. These VFDs should be used with both output filters and shielded cabling. The remaining problem that may arise is EMI from the motor. The remaining harmonics may radiate from the motor just as easily. That cannot be solved with shielding of the cables. You must ensure proper earthing of the motor as well and it should be enclosed in a proper metal casing. It should also be noted that VFD frequency changes cause harmonics in the output. If you turn on/off the hard way, then you can introduce some transients that are very hard to control. The best way is to control the up-/down-going frequency such that no abrupt changes can occur and therefore no transients are allowed to be created due to too fast changes. -- Greetings Bertho (disclaimers are disclaimed) -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Karlsson Wang nicklas.karls...@karlssonwang.se -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought
Re: [Emc-users] VFD causing limits to trip. Huh?
I think you are right and will just try to dig a little bit deeper. A shield is primarily intended to prevent electrostatic coupling from the outside world. So by grounding in the consuming end the shield will get the ground potential of the consumer and the signal cables will be shielded from different external electric fields. This should motivate why as you say the shield should be connected in this end only. If there are current there is also a potential difference. I consider the VFD to be a noise source since it have common mode voltage which will emit an electrical field. There is also a capacitance between the VFD cables and shield. Since Shield impedance on high frequency is far from zero the shield around the VFD cables will not be at GND potential. The most common method is to increase common mode inductance by a filter but I have also seen active filters which reduce the common mode voltage and multiple step voltage inverters. Nicklas Karlsson On Mon, 16 Mar 2015 09:41:15 -0500 Steve Stallings steve...@newsguy.com wrote: I would recommend that shielded signal cables have the shield grounded only at the end where the signals are consumed. If a ground is needed by the device at the end of the cable, you should use a conductor inside rather than the shield itself. If there are signals going both ways, provide the shield ground connection at the end where the most sensitive signals are consumed. The purpose of grounding only one end of the shield is to prevent current from flowing in the shield itself and distorting the signals due to electromagnetic coupling. A shield is primarily intended to prevent electrostatic coupling from the outside world. If the cable does not contain sensitive signals, such as the power cable from a VFD to the spindle, then it is acceptable to ground both ends of the shield. Steve Stallings www.PMDX.com -Original Message- From: Matt Tucci [mailto:matt2c1...@gmail.com] Sent: Monday, March 16, 2015 7:54 AM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] VFD causing limits to trip. Huh? Are the shielded wires only grounded at one end and at the controller end? On Sun, Mar 15, 2015 at 1:22 PM, Karlsson Wang nicklas.karls...@karlssonwang.se wrote: I think grounding is the most important. There are normally a common mode voltage at the inverter output to motor so the inverter power ground will bounce around each time inverter is switched. If this bouncing is coupled to the logic ground there may be a lot of problems. Nicklas Karlsson On Sun, 15 Mar 2015 14:39:24 + (GMT) russ...@lls.lls.com (Russell Brown) wrote: I promised to report back so... I fitted the filter (Schaffner FN2030 Series 16A 250 V ac 400Hz) on the VFD mains input and that did make a difference. My failing case job ran 70% of the way through where without it the job failed 10% in. Not the complete solution though. I then tried a ferrite core (mains clipon stylee) on the input of the field power supply. No difference. A ferrite core (ring with both wires looped through it a couple of times) on the output of the 12V field power made no difference either. A ferrite core (ring as above) on the limit switch wires fitted at the Mesa end made no difference either. So... finally I replaced the limit switch wires with shielded cable (grounded only at the Mesa end). That seemed to do the final trick and the job ran all the way through. Of course I don't know if this is a 100% fix or just enough to get through my failing case (other jobs without all the above have run fine). I guess time will tell. Hope that's useful for someone. -- Regards, Russell | Russell Brown | MAIL: russ...@lls.com PHONE: 01780 471800 | | Lady Lodge Systems | WWW Work: http://www.lls.com | | Peterborough, England | WWW Play: http://www.ruffle.me.uk | -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Mesa 7i8- hal load string
Hi I am looking for an example of the load string in the hal file for the 7i80. I have done as the manual directed but I am not sure if it is correct. I still cannot get the 7i80 to communicate with the hm2 driver. The board mac is read but there it ends. - Regards / Groete Marius D. Liebenberg +27 82 698 3251 +27 12 746 6064 -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Ethernet!
I didn't hear about RT-Net before, I read now and it looks good. If slaves could be implemented on ordinary micro controllers like STM32F4 there are cheap development boards available although with 100Mbit but not gigabit ethernet. Nicklas Karlsson On Sun, 15 Mar 2015 12:20:24 -0700 (PDT) Peter C. Wallace p...@mesanet.com wrote: On Sun, 15 Mar 2015, Karlsson Wang wrote: Date: Sun, 15 Mar 2015 20:03:56 +0100 From: Karlsson Wang nicklas.karls...@karlssonwang.se Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Ethernet! You are right, there are more bandwidth but there may be collisions. I do not now about the switches but for old HUBs the full bandwidth can't be used because of collision and there actually is a statistical upper limit below maximum capacity. Worst case delay is of course higher. There are no collisions in a real time Ethernet system, for example RT-Net uses TDM so each device gets its own time slot. Ethercat allows a higher update rate for situations where many devices have small amounts of data since it eliminates the inter-packet delays but GigE has higher useable bandwidth if the amount of data is larger. For ethercat full bandwidth can be utilized without collisions even if there are several devices. I have chosen ethernet because I think it will be good enough, it is available in almost all computers and there are cheap development boards available with 100Mbit ethernet. I think Ethercat make a lot of sensors for manufacturers since there are no collisions or statistics involved so they could prove the system work correct but for a machine built to be used by yourself this proof is rather useless. Nicklas Karlsson On Sun, 15 Mar 2015 10:58:38 -0700 (PDT) Peter C. Wallace p...@mesanet.com wrote: On Sun, 15 Mar 2015, Karlsson Wang wrote: Date: Sun, 15 Mar 2015 18:34:13 +0100 From: Karlsson Wang nicklas.karls...@karlssonwang.se Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Klemen Dovrtel klemen_dovr...@yahoo.com, Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Ethernet! I have tried Ethernet and it works but if you connect to a switch, hub or similar with more devices there may of couse be real time problems. Ethernet is cheap and readily avaiable although Ethercat I expect to be better if the extra bandwidth is needed. Nicklas Karlsson Actually regular Ethernet GigE is better for bandwidth than Ethercat (AFAIK EtherCAT is limited to 100 mbit by current hardware) On Sat, 14 Mar 2015 18:09:24 + (UTC) Klemen Dovrtel klemen_dovr...@yahoo.com wrote: I am also interested in rt ethernet. Can you please point out which instruction are these, RegardsKlemen On Friday, March 13, 2015 3:54 PM, sam sokolik sa...@empirescreen.com wrote: I still cannot believe that it is possible. I have been testing 2.7+ uspace for a while now. It defiantly opens up options. Building the latest rt-preemt using peters instructions and .config made the latency on this laptop much much better. I am running a 2khz servo thread for a day now. http://electronicsam.com/images/KandT/testing/0313150923b.jpg Realtime communication over Ethernet is just darn awesome! I would not use a laptop for normal machine running - but for developing systems - it sure will be nice. Thanks Peter, Micges, Jeff and everyone else that has made this a reality. sam -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] VFD causing limits to trip. Huh?
Pardon my ignorance... But is there a significant difference between use of shielded cable between VFD and motor vrs lines in hard or flex metal conduit which makes a complete ground at each end? Thanks Greg -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] VFD causing limits to trip. Huh?
On 03/16/2015 07:33 PM, Greg Bentzinger wrote: Pardon my ignorance... But is there a significant difference between use of shielded cable between VFD and motor vrs lines in hard or flex metal conduit which makes a complete ground at each end? Both cable-shield and a conducting cable-pipe will work the same for most practical purpuses. The trick for effective shields is that it should not carry the ground (current) from one side to the other. If the shield is grounded on both sides, then you most probably leak the signal at the shield (the signal is no longer contained). The *real* difference is that a (properly) shielded cable has tightly controlled impedance and coaxial properties, which is an important attribute and a requirement for most application. Using a pipe will have an impedance at some level and is not guaranteed to be the same over the entire length. The result is that you may introduce signal reflection when using a pipe(*). Usually, the shield is connected at one (!) star-point connection to earth where all earth and shield connections come together. It may then be connected from there to ground using a parallel RC 100..1000k//1..100n@1..2kV (may need to experiment with values for best suppresion). The resistor is to level any potential (static) buildup and the capacitor shorts the AC components. It is a lot cheaper to use a pipe and run some wires in there. But, as said before, you need to measure the exact impact of doing so. You may end up worse if you do it wrongly. (*) With high power signals, such as motor driving lines, reflections can overload the drivers or the feeding PSU. High-power lines should always be as short as possible and tightly impedance controlled. -- Greetings Bertho (disclaimers are disclaimed) -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Mesa 7i8- hal load string
Peter I tried the sample that you send and the error remains. Could it be that the 7i80 takes to long to respond. I looked at the code where the board is probed and it would seem that the read is performed directly after the send and if nothing is received it will give this error. I did not look deeper at the receive procedure to see if it actually waits for a packet or just goes on without waiting. It seems there is no timeout or delay. -- Original Message -- From: Peter C. Wallace p...@mesanet.com To: Marius Liebenberg mar...@mastercut.co.za; Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: 2015-03-16 18:49:36 Subject: Re: [Emc-users] Mesa 7i8- hal load string On Mon, 16 Mar 2015, Marius Liebenberg wrote: Date: Mon, 16 Mar 2015 16:23:18 + From: Marius Liebenberg mar...@mastercut.co.za To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Mesa 7i8- hal load string Thanks Peter that is a good start. Is the order of invocation in the hal file important. Maybe give me an example as well. Sorry man I am plucking at straws here as I am at my wits end with stuff I know nothing about :) The hal files are pretty much identical to hm2 hal files for PCI or EPP cards with the exception of the different driver name and added ip address token on the driver command line Here's an example hal/ini file set for a 7I92 freeby.mesanet.com/7i92step.zip -- Original Message -- From: Peter C. Wallace p...@mesanet.com To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: 2015-03-16 16:53:07 Subject: Re: [Emc-users] Mesa 7i8- hal load string On Mon, 16 Mar 2015, Marius Liebenberg wrote: Date: Mon, 16 Mar 2015 07:19:38 + From: Marius Liebenberg mar...@mastercut.co.za To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: [Emc-users] Mesa 7i8- hal load string Hi I am looking for an example of the load string in the hal file for the 7i80. I have done as the manual directed but I am not sure if it is correct. [HOSTMOT2] DRIVER=hm2_eth board_ip=10.10.10.10 BOARD=7i80 CONFIG=num_encoders=1 num_stepgens=5 sserial_port_0=20xx I still cannot get the 7i80 to communicate with the hm2 driver. The board mac is read but there it ends. - Regards / Groete Marius D. Liebenberg +27 82 698 3251 +27 12 746 6064 -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now.
