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Phase Converters
Hi guys,
I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase. Thanks for the help. Joe... |
Google under my handle for a recent discussion, and a lot of links.
I think a static will be OK. Certainly quieter than a rotary! But, others have suggested going w/ VFDs, killing a few birds w/ one stone: 3 phase AND variable speed for your 'port. Not bad! ---------------------------- Mr. P.V.'d formerly Droll Troll "JB" wrote in message ... Hi guys, I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase. Thanks for the help. Joe... |
I have been online Googling pahse converters. Will a static phase
converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? The static phase converter will work, but you'll be a little light on power, particularly since you already only have 1 HP. With static converters the motors run at 2/3's of the full rating. If you only doing work that doesn't need heavy cuts, you'll be ok, but if you need to make some serious cuts you could have problems. I ran a 2HP Bridgeport with a static converter for many years and it never felt low on power even though we often took some pretty big cuts in steel, but with only half that power I think it would have been an issue. However, if you can squeeze up the extra dough I would strongly consider buying a VFD for the mill instead of a static converter or rotary converter. VFD's rated for 1HP are pretty affordable. See www.dealerselectric.com for some pricing. In addition to giving you true 3 phase from single phase input you'll also get speed control and controlled braking and reversing if you buy the optional braking resistor. If you have a step pulley mill this is a great enhancement. I have a VFD on my 2HP Bridgeport step pulley clone and I hardly every change the pulley setting and I never have to use the manual brake anymore. The controlled reversing is great for power tapping. Good luck- Paul T. |
Thanks, I'll do a search now. Do you have any suggestions on a VFD and what
do they cost. Thanks again. Joe... "Proctologically Violated©®" wrote in message ... Google under my handle for a recent discussion, and a lot of links. I think a static will be OK. Certainly quieter than a rotary! But, others have suggested going w/ VFDs, killing a few birds w/ one stone: 3 phase AND variable speed for your 'port. Not bad! ---------------------------- Mr. P.V.'d formerly Droll Troll "JB" wrote in message ... Hi guys, I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase. Thanks for the help. Joe... |
http://www.dealerselectric.com
I like the TECO Westinghouse units [posted and mailed] "JB" wrote in : Thanks, I'll do a search now. Do you have any suggestions on a VFD and what do they cost. Thanks again. Joe... "Proctologically Violated©®" wrote in message ... Google under my handle for a recent discussion, and a lot of links. I think a static will be OK. Certainly quieter than a rotary! But, others have suggested going w/ VFDs, killing a few birds w/ one stone: 3 phase AND variable speed for your 'port. Not bad! ---------------------------- Mr. P.V.'d formerly Droll Troll "JB" wrote in message ... Hi guys, I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase. Thanks for the help. Joe... |
"Paul T." wrote in message ... I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? The static phase converter will work, but you'll be a little light on power, particularly since you already only have 1 HP. With static converters the motors run at 2/3's of the full rating. If you only doing work that doesn't need heavy cuts, you'll be ok, but if you need to make some serious cuts you could have problems. I ran a 2HP Bridgeport with a static converter for many years and it never felt low on power even though we often took some pretty big cuts in steel, but with only half that power I think it would have been an issue. However, if you can squeeze up the extra dough I would strongly consider buying a VFD for the mill instead of a static converter or rotary converter. VFD's rated for 1HP are pretty affordable. See www.dealerselectric.com for some pricing. In addition to giving you true 3 phase from single phase input you'll also get speed control and controlled braking and reversing if you buy the optional braking resistor. If you have a step pulley mill this is a great enhancement. I have a VFD on my 2HP Bridgeport step pulley clone and I hardly every change the pulley setting and I never have to use the manual brake anymore. The controlled reversing is great for power tapping. Electric braking is a little tough on the motor/windings, no? ---------------------------- Mr. P.V.'d formerly Droll Troll Good luck- Paul T. |
Paul,
Thanks for the input. Marty and seberal others recommended the same dealer. I went to the web site and I am a little confused as to which model I should buy. Do i need to but an electrical box to install the unit in? Does it get mounted on the mill? Thanks again for all your help. Joe... "Paul T." wrote in message ... I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? The static phase converter will work, but you'll be a little light on power, particularly since you already only have 1 HP. With static converters the motors run at 2/3's of the full rating. If you only doing work that doesn't need heavy cuts, you'll be ok, but if you need to make some serious cuts you could have problems. I ran a 2HP Bridgeport with a static converter for many years and it never felt low on power even though we often took some pretty big cuts in steel, but with only half that power I think it would have been an issue. However, if you can squeeze up the extra dough I would strongly consider buying a VFD for the mill instead of a static converter or rotary converter. VFD's rated for 1HP are pretty affordable. See www.dealerselectric.com for some pricing. In addition to giving you true 3 phase from single phase input you'll also get speed control and controlled braking and reversing if you buy the optional braking resistor. If you have a step pulley mill this is a great enhancement. I have a VFD on my 2HP Bridgeport step pulley clone and I hardly every change the pulley setting and I never have to use the manual brake anymore. The controlled reversing is great for power tapping. Good luck- Paul T. |
On Sun, 20 Mar 2005 13:02:29 -0500, "JB"
wrote: Hi guys, I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase. Thanks for the help. Joe... JB..Id go with a rotary...simply for the fact you may well wind up with other 3 ph machine tools in the future. And the Statics do NOT deliver full power to the machine. On the other hand....rather than going with either, unless you want to build a cheap RPC, Id hunt around for a 3hp VFD, and utilize the far nicer ability to have virtually infinite speed ranges, instant reverse for tapping, and so forth. And with the 3hp VFD...it can be run at full power on single phase..it will make up the third leg just like the converters. Just my .02USD Gunner Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken |
Thanks Gunner. With the advice I have received from some of the members of
the group, I am leaning towards VFD. Thaks. For the help. Joe... "Gunner" wrote in message ... On Sun, 20 Mar 2005 13:02:29 -0500, "JB" wrote: Hi guys, I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase. Thanks for the help. Joe... JB..Id go with a rotary...simply for the fact you may well wind up with other 3 ph machine tools in the future. And the Statics do NOT deliver full power to the machine. On the other hand....rather than going with either, unless you want to build a cheap RPC, Id hunt around for a 3hp VFD, and utilize the far nicer ability to have virtually infinite speed ranges, instant reverse for tapping, and so forth. And with the 3hp VFD...it can be run at full power on single phase..it will make up the third leg just like the converters. Just my .02USD Gunner Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken |
On Sun, 20 Mar 2005 13:33:36 -0500, "Proctologically Violated©®"
wrote: "Paul T." wrote in message .. . I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? The static phase converter will work, but you'll be a little light on power, particularly since you already only have 1 HP. With static converters the motors run at 2/3's of the full rating. If you only doing work that doesn't need heavy cuts, you'll be ok, but if you need to make some serious cuts you could have problems. I ran a 2HP Bridgeport with a static converter for many years and it never felt low on power even though we often took some pretty big cuts in steel, but with only half that power I think it would have been an issue. However, if you can squeeze up the extra dough I would strongly consider buying a VFD for the mill instead of a static converter or rotary converter. VFD's rated for 1HP are pretty affordable. See www.dealerselectric.com for some pricing. In addition to giving you true 3 phase from single phase input you'll also get speed control and controlled braking and reversing if you buy the optional braking resistor. If you have a step pulley mill this is a great enhancement. I have a VFD on my 2HP Bridgeport step pulley clone and I hardly every change the pulley setting and I never have to use the manual brake anymore. The controlled reversing is great for power tapping. Electric braking is a little tough on the motor/windings, no? Not on decent motors. Gunner ---------------------------- Mr. P.V.'d formerly Droll Troll Good luck- Paul T. Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken |
On Sun, 20 Mar 2005 14:34:44 -0500, "JB"
wrote: Thanks Gunner. With the advice I have received from some of the members of the group, I am leaning towards VFD. Thaks. For the help. My pleasure. My big old Gorton MasterMill, with the pulley head, became a marvelous machine to use, once I added a VFD and made up a "pendant" (remote control) and attached it to the head. The Gorton looks like a Bridgeport on steroids G. Ive also done the same with quite a number of Hardinge lathes for customers, as well as a 1501 Clausing here at my home. Its good tech, and works damned well. Btw...check Ebay also for good deals on VFDs. Some commerical sellers sell via Ebay and you can get some decent deals, with warranty, and of course lots of used ones. As in any used item involving electronics...I would strongly suggest reading the sellers feedback..but Ive helped a number of folks who have bought used ones off Ebay, all with great sucess. The "braking resistor" can usually be picked up at a surplus electronics place for a couple bucks at most..so shrug... Gunner Gunner Joe... "Gunner" wrote in message .. . On Sun, 20 Mar 2005 13:02:29 -0500, "JB" wrote: Hi guys, I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase. Thanks for the help. Joe... JB..Id go with a rotary...simply for the fact you may well wind up with other 3 ph machine tools in the future. And the Statics do NOT deliver full power to the machine. On the other hand....rather than going with either, unless you want to build a cheap RPC, Id hunt around for a 3hp VFD, and utilize the far nicer ability to have virtually infinite speed ranges, instant reverse for tapping, and so forth. And with the 3hp VFD...it can be run at full power on single phase..it will make up the third leg just like the converters. Just my .02USD Gunner Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken |
Check out automation direct at:
http://web3.automationdirect.com/adc...ves_-z-_Motors Take a look at the GS1 and GS2 series of "microdrives". I have been using a GS1 on my old SB vertical mill for a couple of years. Works perfectly! I have 220V 1 phase in, 230, 3 ph out on a 1 HP motor. I have used these drives (up to 5HP on a GS2) at the place I work and find them to be very reliable and easy to configure. They are a lot of bang for the buck. The 1HP GS1 is around $170.00, if I remember correctly. I could have built a rotary for less money, but lots more time. -AL |
Al,
Thanks for the information. What did you enclose the VFD in? Did you mount it directly to the machine? Thanks again. Joe... wrote in message oups.com... Check out automation direct at: http://web3.automationdirect.com/adc...ves_-z-_Motors Take a look at the GS1 and GS2 series of "microdrives". I have been using a GS1 on my old SB vertical mill for a couple of years. Works perfectly! I have 220V 1 phase in, 230, 3 ph out on a 1 HP motor. I have used these drives (up to 5HP on a GS2) at the place I work and find them to be very reliable and easy to configure. They are a lot of bang for the buck. The 1HP GS1 is around $170.00, if I remember correctly. I could have built a rotary for less money, but lots more time. -AL |
Gunner,
What should I enclose the VFD in? Does it then get mounted to the mill? My sincerest thanks. Joe... "Gunner" wrote in message ... On Sun, 20 Mar 2005 14:34:44 -0500, "JB" wrote: Thanks Gunner. With the advice I have received from some of the members of the group, I am leaning towards VFD. Thaks. For the help. My pleasure. My big old Gorton MasterMill, with the pulley head, became a marvelous machine to use, once I added a VFD and made up a "pendant" (remote control) and attached it to the head. The Gorton looks like a Bridgeport on steroids G. Ive also done the same with quite a number of Hardinge lathes for customers, as well as a 1501 Clausing here at my home. Its good tech, and works damned well. Btw...check Ebay also for good deals on VFDs. Some commerical sellers sell via Ebay and you can get some decent deals, with warranty, and of course lots of used ones. As in any used item involving electronics...I would strongly suggest reading the sellers feedback..but Ive helped a number of folks who have bought used ones off Ebay, all with great sucess. The "braking resistor" can usually be picked up at a surplus electronics place for a couple bucks at most..so shrug... Gunner Gunner Joe... "Gunner" wrote in message . .. On Sun, 20 Mar 2005 13:02:29 -0500, "JB" wrote: Hi guys, I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase. Thanks for the help. Joe... JB..Id go with a rotary...simply for the fact you may well wind up with other 3 ph machine tools in the future. And the Statics do NOT deliver full power to the machine. On the other hand....rather than going with either, unless you want to build a cheap RPC, Id hunt around for a 3hp VFD, and utilize the far nicer ability to have virtually infinite speed ranges, instant reverse for tapping, and so forth. And with the 3hp VFD...it can be run at full power on single phase..it will make up the third leg just like the converters. Just my .02USD Gunner Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken |
On Sun, 20 Mar 2005 15:56:00 -0500, "JB"
wrote: Al, Thanks for the information. What did you enclose the VFD in? Did you mount it directly to the machine? Thanks again. Joe... Hi Joe, This is still AL, just posting from a different computer. I mounted mine in a standard "screw cover" electrical enclosure that I got from a local electrical supply place. I think it is refered to as a NEMA 1 enclosure. There are available in all sorts of sizes. I opened up a few of the knockouts on the sides for ventalation. I did mount it right on my machine just because I had a convinent place for it, down on a post on the rear corner of the base that used to be for a power table feed that I never got with my machine. I mounted the controls (start/stop, speed control pot) in a small plastic box up on the head of the machine. I am likely going to do a similar thing on my lathe, but will likely just mount the VFD on the wall, as the lathe has less space on the base for the drive. hope that helps. AL |
Al,
Again, my sincerest thanks. I'm a bit confused (which is easy to do) what is mounted in the nema box attached to the machine? I thought the speed control would be part of the VFD. Don't you use the normal on off controls aatched to the mill? Joe... "Al A." wrote in message ... On Sun, 20 Mar 2005 15:56:00 -0500, "JB" wrote: Al, Thanks for the information. What did you enclose the VFD in? Did you mount it directly to the machine? Thanks again. Joe... Hi Joe, This is still AL, just posting from a different computer. I mounted mine in a standard "screw cover" electrical enclosure that I got from a local electrical supply place. I think it is refered to as a NEMA 1 enclosure. There are available in all sorts of sizes. I opened up a few of the knockouts on the sides for ventalation. I did mount it right on my machine just because I had a convinent place for it, down on a post on the rear corner of the base that used to be for a power table feed that I never got with my machine. I mounted the controls (start/stop, speed control pot) in a small plastic box up on the head of the machine. I am likely going to do a similar thing on my lathe, but will likely just mount the VFD on the wall, as the lathe has less space on the base for the drive. hope that helps. AL |
On Sun, 20 Mar 2005 23:11:29 -0500, "JB"
wrote: Al, Again, my sincerest thanks. I'm a bit confused (which is easy to do) what is mounted in the nema box attached to the machine? I thought the speed control would be part of the VFD. Don't you use the normal on off controls aatched to the mill? The VFD itself has outputs/inputs for remote controls. You can indeed use the controls on the front of the VFD (if equipped) but its far easier to simply mout a toggle switch and a potentiometer in a small box with a 4-6 conductor cable running to the VFD itself Typically you have a toggle switch, to the left, run forward. Center, Stop, to the right, run reverse, and the potentiometer is the speed control There are some variations..but typially its just a two postion low voltage toggle switch and the pot. Very simple. Gunner Joe... "Al A." wrote in message .. . On Sun, 20 Mar 2005 15:56:00 -0500, "JB" wrote: Al, Thanks for the information. What did you enclose the VFD in? Did you mount it directly to the machine? Thanks again. Joe... Hi Joe, This is still AL, just posting from a different computer. I mounted mine in a standard "screw cover" electrical enclosure that I got from a local electrical supply place. I think it is refered to as a NEMA 1 enclosure. There are available in all sorts of sizes. I opened up a few of the knockouts on the sides for ventalation. I did mount it right on my machine just because I had a convinent place for it, down on a post on the rear corner of the base that used to be for a power table feed that I never got with my machine. I mounted the controls (start/stop, speed control pot) in a small plastic box up on the head of the machine. I am likely going to do a similar thing on my lathe, but will likely just mount the VFD on the wall, as the lathe has less space on the base for the drive. hope that helps. AL Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken |
In article ,
Gunner wrote: On Sun, 20 Mar 2005 23:11:29 -0500, "JB" wrote: Al, Again, my sincerest thanks. I'm a bit confused (which is easy to do) what is mounted in the nema box attached to the machine? I thought the speed control would be part of the VFD. Don't you use the normal on off controls aatched to the mill? The VFD itself has outputs/inputs for remote controls. You can indeed use the controls on the front of the VFD (if equipped) but its far easier to simply mout a toggle switch and a potentiometer in a small box with a 4-6 conductor cable running to the VFD itself Well ... you can wire the original switch contacts to command the VFD, which is my preference, as it keeps the behavior constant. Putting the original motor switch *between* the VFD and the motor can lead to a zapped VFD -- unless the VFD is *way* overpowered for the motor (such as my 7-1/2 HP VFD running a mill with a 1 HP motor. :-) Typically you have a toggle switch, to the left, run forward. Center, Stop, to the right, run reverse, and the potentiometer is the speed control Yep! There are some variations..but typially its just a two postion low voltage toggle switch and the pot. Very simple. SPDTCO (Single Pole, Double Throw, Center Off) is the designation for the switch. Though most VFDs can also be wired to accept three pushbuttons, a NC (Normally Closed) one for the stop function, and a pair of NO (Normally Open) ones for the forward and reverse commands. And shielded wire is a good bet for the connections between your remote controls and the VFD, so electrical noise does not trigger it into various modes when you don't want it to. The longer the wires, and the closer they run to existing power wires, the more important this becomes. Enjoy, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
I uses a phaseomatic on my 2hp encore for 8 years without any problems.
Dan "JB" wrote in message ... Hi guys, I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase. Thanks for the help. Joe... |
The cheap units from www.automationdirect.com work very well. I have a GS2
on my BP and would not be without it. The GS1 is OK, but I wanted a remote keypad that required a GS2. see http://web1.automationdirect.com/adc...ves_-z-_Motors Randy "JB" wrote in message ... Thanks, I'll do a search now. Do you have any suggestions on a VFD and what do they cost. Thanks again. Joe... "Proctologically Violated©®" wrote in message ... Google under my handle for a recent discussion, and a lot of links. I think a static will be OK. Certainly quieter than a rotary! But, others have suggested going w/ VFDs, killing a few birds w/ one stone: 3 phase AND variable speed for your 'port. Not bad! ---------------------------- Mr. P.V.'d formerly Droll Troll "JB" wrote in message ... Hi guys, I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase. Thanks for the help. Joe... |
On Sun, 20 Mar 2005 23:11:29 -0500, "JB"
wrote: Al, Again, my sincerest thanks. I'm a bit confused (which is easy to do) what is mounted in the nema box attached to the machine? I thought the speed control would be part of the VFD. Don't you use the normal on off controls aatched to the mill? Joe... Joe, What Gunner said. I just mounted a small box remotely from the VFD that has just the fwd/rev switch, panic stop button and a speed control pot in it. The VFD is mounted down on the rear side of the mill. AL |
I realize the extent of my confusion about phase converters. I thought
that phase converters were motors/generators coupled on one shaft. It turns out that they are some complicated combinations of capacitors. There are different types of phase converters. A static phase converter is just a couple caps and probably a relay that allows a 3 phase motor to start and run off of 2 windings. It does not develop full power (about 2/3) but is still useful. A rotary phase converter is basically a 3 phase motor running off of single phase power. It will regenerate the third phase well enough to run a smaller 3 phase motor pretty well. Commercial products use a custom wound motor that works a little better than a standard 3 phase motor (so I'm told). Phase converters are not made from motor generators because it is expensive and not necessary unless you have a unique application such as a need to generate 50 Hz from 60 Hz. |
Ignoramus4745 wrote:
I realize the extent of my confusion about phase converters. I thought that phase converters were motors/generators coupled on one shaft. It turns out that they are some complicated combinations of capacitors. I am curious why phase converters are not made as motor/generators. Money. Go price a 5hp 3ph 220V alternator. Wear diapers. I have about $150 into my phase converter total, including new bearings, and megging and revarnishing the stator. GWE |
Chuck
Although I dont mean to correct you about the 2/3 power statement, most 3 phase motors will develop its full name plate HP even when fed single phase. They will slow to a lower RPM than the name plate RPM rating, and get hotter, quicker with single phase than with 3 phase. It is interesting to me to learn that an idler of equal size of the tool motor provides very little MAX. HP performance compared to no idler at all when fed from single phase. The HP from a 3 phase motor driven from single phase without an idler will perform very nearly the same at that same tool motor driven thru an "equal size" idler up to about 60 percent of MAX. HP name plate on the tool motor. Maybe thats where the 2/3 HP figure comes from. Idlers and tuning do help the tool motor measurably when the 3 phaes tool motor is heavily loaded. Jerry "Chuck Sherwood" wrote in message ... I realize the extent of my confusion about phase converters. I thought that phase converters were motors/generators coupled on one shaft. It turns out that they are some complicated combinations of capacitors. There are different types of phase converters. A static phase converter is just a couple caps and probably a relay that allows a 3 phase motor to start and run off of 2 windings. It does not develop full power (about 2/3) but is still useful. A rotary phase converter is basically a 3 phase motor running off of single phase power. It will regenerate the third phase well enough to run a smaller 3 phase motor pretty well. Commercial products use a custom wound motor that works a little better than a standard 3 phase motor (so I'm told). Phase converters are not made from motor generators because it is expensive and not necessary unless you have a unique application such as a need to generate 50 Hz from 60 Hz. |
Ignoramus4745 wrote:
I realize the extent of my confusion about phase converters. I thought that phase converters were motors/generators coupled on one shaft. It turns out that they are some complicated combinations of capacitors. I am curious why phase converters are not made as motor/generators. i I suppose they could be considered a motor/alternator, just not separate units. Don't let the thought that they are complicated slow you down, they're not all that involved. A clamp-on ammeter is good for balancing, they can be had on ebay for around $10 the last time I looked- the basic Radio Shack unit works well. You don't have to use any capacitors at all if you don't want- you can start it with a small single-phase motor or if you want to go all the way simple you can start it with a pull-rope wrapped around the motor shaft.. but make sure the is pulled clear of the shaft before switching it on. The advantage of the caps is that you can make it more efficient.. John |
What Grant said . . . a single phase motor driving a generator would, in
fact, be a motor/generator -- but -- the 3 phase generator portion of the combination would have to be an alternator; a machine with a stationery set of coils (stator) and a revolving magnetic field set of coils, or vice versa. The field would either have to be excited by direct current (DC) or be made up of permanent magnets. Large steam driven turbo-alternators are an example. Those are synchronous machines, whereby the speed of rotation determines the output frequency; their magnetic fields are generally excited by DC generators of 110 volts, sometimes 220, and their may be other DC voltages for excitation. Contrast this to a rotary phase converter. The type RPC we are familiar with is basically 2 three-phase motors running on single-phase current with their 3rd legs tied together. The motors are not operated in parallel. They may run with or without capacitor augmentation which aids in supplying phased current to the 3rd leg of each motor. In a manner of speaking each motor is a sort of rotating transformer which is responsible for energizing the 3rd leg or "manufactured phase". The idler motor, viewed as a source ( not a strictly accurate analogy) has to be larger than the load motor in order to keep the 3rd leg "generated" voltage from sagging down. Capacitance from the single-phase line to the 3rd leg(s) lowers impedance in those paths and may be thought of as forming a very broadly tuned series resonance circuit. Current flow in a RPC is quite complex and does not readily yield itself to mathematical modeling.. Bob Swinney |
In article ,
Chuck Sherwood wrote: I realize the extent of my confusion about phase converters. I thought that phase converters were motors/generators coupled on one shaft. It turns out that they are some complicated combinations of capacitors. There are different types of phase converters. A static phase converter is just a couple caps and probably a relay that allows a 3 phase motor to start and run off of 2 windings. It does not develop full power (about 2/3) but is still useful. A rotary phase converter is basically a 3 phase motor running off of single phase power. It will regenerate the third phase well enough to run a smaller 3 phase motor pretty well. Commercial products use a custom wound motor that works a little better than a standard 3 phase motor (so I'm told). And these have a few capacitors and a voltage sensitive relay to make it self-starting. They may (and good ones will) have additional capacitors to tune the balance of the generated phase, and to balance out imaginary current in the draw from the breaker box which can draw more from your breakers than is convenient. Phase converters are not made from motor generators because it is expensive and not necessary unless you have a unique application such as a need to generate 50 Hz from 60 Hz. Or a need for 400 Hz 3 phase to run aircraft electronic and navigation equipment. A maker of that style of converter is Georator (in Manassas VA). And yes -- they are a *lot* more expensive than an idler motor used as a rotary converter. Enjoy, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
Although I dont mean to correct you about the 2/3 power statement, most 3
phase motors will develop its full name plate HP even when fed single phase. I think I read that on the phase a matic web site but I could be wrong. I always thought it was related to the fact that the the motor is running on only 2 out of its three windings. At 2/3 rate HP, the two working windings will be drawing full rated current. Anything over 2/3 would imply that the 2 working windings must draw more that full load current. Based on this logic, I accept the 2/3 rating They will slow to a lower RPM than the name plate RPM rating, and get hotter, quicker with single phase than with 3 phase. Wouldn't that imply that it might be operating outside of safe limits? The HP from a 3 phase motor driven from single phase without an idler will perform very nearly the same at that same tool motor driven thru an "equal size" idler up to about 60 percent of MAX. HP name plate on the tool motor. From what limited testing I have done, I agree that an idler motor does not apear to do much until the tool motor is at a higher slip than the idler motor. There was a guy on here that stated his surface grinder did not work perfectly with a rotary phase converter and worked much better with a VFD. This appears to support this conclusion. One thing that a RPC does do is provide instant reverse that you cannot get with it. Frankly I decided not to get two wrapped up in phase converters because I prefer VFDs. |
Would it be correct that all these phase converters that are not based
on motor/generators, are unable to run more than one 3 phase device at a time. That is not correct. Rotary phase converters are often used to run multiple machines. One at a time or even more that one at a time. Do a web search for "phase a matic" and read all about it. |
In article , Ignoramus27341 says...
Would it be correct that all these phase converters that are not based on motor/generators, are unable to run more than one 3 phase device at a time. Permit me to turn your statement inside out a bit, but retain the original meaning: "All these phase converters based on motor-generators (sic) can run more than one device at a time." As others have suggested, motor-generator setups are not typically found in this application. The rotary phase converer which consists of a large three-phase motor, acting as a sort of rotary transformer, has rotating elements and will provide nearly factory-fresh 3~ power, and can run many machines at once. In fact, the more load machines running, the larger the apparent capacity of the system. My idler motor setup powers a milling machine and two lathes: http://www.metalworking.com/DropBox/_2000_retired_files/Conv.jpg http://www.metalworking.com/DropBox/_2000_retired_files/conv.txt Jim -- ================================================== please reply to: JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com ================================================== |
I can get a 3 phase motor basically for free, this or next week. A
very pleasant guy from whom I already got a bunch of stuff from his liquidating factory, needs to dispose of his stuff. I posted what I bought in the "My latest catch" thread. I am VERY interested in making my own phase converter. Are you the guy that lives in downers grove IL? If so, you are close to me and I would also like to find a motor to make a phase converter. A 5HP would be about right. A 7.5 would probalby work too. chuck |
In article , Ignoramus27341 says...
Thanks. I feel quite lost. Is what you have not the same as motor/generator (with the 3 phase motor being the generator)? Hmm. Yoda-speak you do. I have a rotary phase converter. It isn't a motor-generator because the idler motor is only a simple three phase induction motor. Jim -- ================================================== please reply to: JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com ================================================== |
In article , Ignoramus27341 says...
I am beginning to "get it". You spin up your 3 phase motor by using the little 1 phase motor. Then you apply single phase power to the 3 phase motor. The third leg of the three phase motor starts producing an out of phase thrd phase. At this point, you turn off the little 1 phase motor and start using the 3 phase motor. Is that right? Exactly correct. If you read the .txt file it sorta goes through the drill on using it. Close small switch to energize pony motor (it's a 1/8 hp repulsion-induction motor), and wait for the 5 hp motor to come up to speed. That takes all of one second or so. Then I close the fused knife switch to apply single phase 240 volt excitation to two leads of the 5 hp idler motor. It then picks up and locks to the line frequency. Then I shut off the pony motor, and lift up the hinged platform so the belt flips off. I deftly catch it and tuck it under the platform so the thing doesn't rattle. Now the three wires (two of which go to incoming 240 volt line) from the idler motor give pretty good three phase power, which is routed via my distribution buss, to each load machine that I would want to run. The converter is quiet enough so that I've been known to accidentally leave it running when I quit working. Jim -- ================================================== please reply to: JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com ================================================== |
Unfortunately, I called the seller and he said that he only has motors
up to 1 HP. Too small to make a useful rotary phase converter. cs |
On Wed, 20 Jul 2005 18:43:02 GMT, Ignoramus27341
wrote: On 20 Jul 2005 11:05:12 -0700, jim rozen wrote: In article , Ignoramus27341 says... Would it be correct that all these phase converters that are not based on motor/generators, are unable to run more than one 3 phase device at a time. Permit me to turn your statement inside out a bit, but retain the original meaning: "All these phase converters based on motor-generators (sic) can run more than one device at a time." As others have suggested, motor-generator setups are not typically found in this application. The rotary phase converer which consists of a large three-phase motor, acting as a sort of rotary transformer, has rotating elements and will provide nearly factory-fresh 3~ power, and can run many machines at once. In fact, the more load machines running, the larger the apparent capacity of the system. My idler motor setup powers a milling machine and two lathes: http://www.metalworking.com/DropBox/_2000_retired_files/Conv.jpg http://www.metalworking.com/DropBox/_2000_retired_files/conv.txt Thanks. I feel quite lost. Is what you have not the same as motor/generator (with the 3 phase motor being the generator)? I can get a 3 phase motor basically for free, this or next week. A very pleasant guy from whom I already got a bunch of stuff from his liquidating factory, needs to dispose of his stuff. I posted what I bought in the "My latest catch" thread. I am VERY interested in making my own phase converter. i With a motor-generator the generator generates all three phases. With the typical Rotary Phase Converter only 1 of the three phases is generated. The other two come from the two legs of the 220 single phase that power the RPC. So when you connect your three phase motor to the RPC two of the wires connect to the single phase wires that are also connected to the RPC. The other wire connects to the wire from the RPC that is not connected to the single phase line. Capacitors are used to balance the RPC and to provide a self starting feature so the small single phase motor can be disposed with. But a quick and dirty one can even be built using just a three phase motor and a rope. Wind the rope around the motor shaft and pull it to spin the motor up. When the rope comes off turn on the single phase power and if the motor is spinning fast enough it will speed up to normal running speed. I have a well balanced RPC in my shop that is made from a 15 HP motor. At idle it draws about 1500 watts. It can start a 15 HP motor but can run 60 HP when the motors are connected in steps. Currently it is used to run two CNC lathes with 10 HP spindles, 1 CNC mill with a 5 HP spindle, and various other manual manual machines. ERS |
"Chuck Sherwood" wrote in message ... Although I dont mean to correct you about the 2/3 power statement, most 3 phase motors will develop its full name plate HP even when fed single phase. I think I read that on the phase a matic web site but I could be wrong. I always thought it was related to the fact that the the motor is running on only 2 out of its three windings. At 2/3 rate HP, the two working windings will be drawing full rated current. Anything over 2/3 would imply that the 2 working windings must draw more that full load current. Based on this logic, I accept the 2/3 rating They will slow to a lower RPM than the name plate RPM rating, and get hotter, quicker with single phase than with 3 phase. Wouldn't that imply that it might be operating outside of safe limits? The HP from a 3 phase motor driven from single phase without an idler will perform very nearly the same at that same tool motor driven thru an "equal size" idler up to about 60 percent of MAX. HP name plate on the tool motor. From what limited testing I have done, I agree that an idler motor does not apear to do much until the tool motor is at a higher slip than the idler motor. There was a guy on here that stated his surface grinder did not work perfectly with a rotary phase converter and worked much better with a VFD. This appears to support this conclusion. One thing that a RPC does do is provide instant reverse that you cannot get with it. Frankly I decided not to get two wrapped up in phase converters because I prefer VFDs. Chuck I have made some measurements on my dyno with various sized idlers feeding tool motors. My data shows that the idler who's HP size is about equal to the tool motor size will provide very little improvement over *no* idler. They will bioth produce chatter at high load. If a person wants to run a 3 phase surface grinder thru an idler from single phase, he has choosen a difficult task because the grinder it extra sensitive to the torque chatter. An idler for runing a 3 phase surface grinder from single phase should probably be several times the grinder motor's HP and tuned for max smoothness at the load expected. I couldnt finish my experiment with motor heating due to load on the tool motor. I ran out of interest. But, my preliminary data showed that the 3 phase tool motor gets warm rather slowly even at near max HP when supplied single phase. The unfed winding supplies some heat sink. And, a home/hobby/money saver guy could easily provide a little extra fan to cool the motor. I have no clear cut favorites when choosing how to use 3 phase motors when only single phase is available. VFDs can be a little more expensive, and do put some RFI in the shop. Jerry |
In article ,
Chuck Sherwood wrote: Would it be correct that all these phase converters that are not based on motor/generators, are unable to run more than one 3 phase device at a time. That is not correct. Rotary phase converters are often used to run multiple machines. One at a time or even more that one at a time. Agreed -- but he said "*not* based on motor/generators", which I think he intended to also exclude idlers used as rotary phase converters. The idler motor is serving both as a motor and a generator at the same time. "Static" phase converters ("Phase-o-Matic" is an example) are not only limited to running one thing at a time, but are also designed for a fairly narrow range of load motor horsepower. If you need to start a 1HP motor, and a 2-1/2 HP motor, the odds are that you can't even switch the converter from one load to the other to run one at a time, because the starting capacitor value will be wrong for at least one of them. "Rotary" phase converters, build around an idler motor, can not only run more than one load motor at a time, but can even handle more load horsepower when doing so, because each load motor already running off of it contributes to the "rotary converter" effect. So, if you have a 1HP motor on your lathe, and a 1-1/2 HP motor acting as your idler, you have a greater chance of starting another machine whose motor is perhaps a 2HP rating if the lathe motor is already running. Do a web search for "phase a matic" and read all about it. Yes, that will help. Note that "Phase-o-Matic" makes both static converters and rotary converters. (And a static converter can actually serve as the starting equipment on an idler for your own rotary converter.) Enjoy, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
In article ,
Ignoramus27341 wrote: On 21 Jul 2005 00:36:58 -0400, DoN. Nichols wrote: [ ... ] "Rotary" phase converters, build around an idler motor, can not only run more than one load motor at a time, but can even handle more load horsepower when doing so, because each load motor already running off of it contributes to the "rotary converter" effect. So, if you have a 1HP motor on your lathe, and a 1-1/2 HP motor acting as your idler, you have a greater chance of starting another machine whose motor is perhaps a 2HP rating if the lathe motor is already running. Would it be also correct to say that after the phase converter started the 3 phase motor, the third leg can be turned off? Only if you want to have the lowered long-term horsepower out of the motor that running it from a "static" phase converter would give you. There is little point to doing this, and lots of reasons to *not* do this. The *start* capacitors are removed from the idler motor once it is up to speed. This can be done for you by a "static" converter, if you already have one, or don't want to chase down the parts needed to build the starting circuit. For better efficiency, you may want to use run capacitors between L1 and the generated phase, and/or L2 and the generated phase. For lower current from the breaker (real + imaginary current), you may wish to add capacitors across L1 and L2, adjusting the value until the current from the breaker is at a minimum. On a residential system, you are not charged for the imaginary current, but it can cause nuisance trips of the circuit breaker, which can't distinguish between "real" and "imaginary" current. But both of these are fancy tweaks, and you can run without them, just as you can run without a start capacitor if you use a single phase "pony motor" to spin up the idler. If *I* were to build a rotary converter, it would be self-starting, and would have both run capacitors and the current-reduction capacitor. Enjoy, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
Iggy sez: Would it be also correct to say that after the phase converter
started the 3 phase motor, the third leg can be turned off? Static phase converters, i.e. Phase-a-Matic, etc, only energize the 3rd leg during start-up time. After that brief interval, the static phase converter effectively switches "off" (back to a standby mode) and your 3-phase motor continues to run on single-phase power. No 3-phase "power" is available from a static converter except for starting purposes. This takes advantage of the fact that a 3-phase motor will continue to run on single-phase "power" after the motor is spun-up via auxiliary means, be that a rope, start capacitors, large hamster, etc. IMO, if you made the effort to learn a bit about RPCs before trying to jump in and build one, you'd find most of the "mystique" would fade away. You'd be left with the confidence and good warm fuzzy feeling of being in command of your project. There is a wealth of information re. RPCs on the Internet. If you can find a copy of "The Home Shop Machinist", Nov./Dec. 2000, it has a pretty comprehensive article about RPCs. Bob Swinney "Ignoramus27341" wrote in message .. . On 21 Jul 2005 00:36:58 -0400, DoN. Nichols wrote: In article , Chuck Sherwood wrote: Would it be correct that all these phase converters that are not based on motor/generators, are unable to run more than one 3 phase device at a time. That is not correct. Rotary phase converters are often used to run multiple machines. One at a time or even more that one at a time. Agreed -- but he said "*not* based on motor/generators", which I think he intended to also exclude idlers used as rotary phase converters. The idler motor is serving both as a motor and a generator at the same time. I did not mean to exclude idlers. At the time when I asked my question, I did not understand the role of idler. Now I do understand its role, thanks to Jim Rozen's pictures. "Rotary" phase converters, build around an idler motor, can not only run more than one load motor at a time, but can even handle more load horsepower when doing so, because each load motor already running off of it contributes to the "rotary converter" effect. So, if you have a 1HP motor on your lathe, and a 1-1/2 HP motor acting as your idler, you have a greater chance of starting another machine whose motor is perhaps a 2HP rating if the lathe motor is already running. i |
Correction: Make that Nov/Dec 2001 Home Shop Machinist. Damned proof
reader, anyway! Bob Swinney "Robert Swinney" wrote in message ... Iggy sez: Would it be also correct to say that after the phase converter started the 3 phase motor, the third leg can be turned off? Static phase converters, i.e. Phase-a-Matic, etc, only energize the 3rd leg during start-up time. After that brief interval, the static phase converter effectively switches "off" (back to a standby mode) and your 3-phase motor continues to run on single-phase power. No 3-phase "power" is available from a static converter except for starting purposes. This takes advantage of the fact that a 3-phase motor will continue to run on single-phase "power" after the motor is spun-up via auxiliary means, be that a rope, start capacitors, large hamster, etc. IMO, if you made the effort to learn a bit about RPCs before trying to jump in and build one, you'd find most of the "mystique" would fade away. You'd be left with the confidence and good warm fuzzy feeling of being in command of your project. There is a wealth of information re. RPCs on the Internet. If you can find a copy of "The Home Shop Machinist", Nov./Dec. 2000, it has a pretty comprehensive article about RPCs. Bob Swinney "Ignoramus27341" wrote in message .. . On 21 Jul 2005 00:36:58 -0400, DoN. Nichols wrote: In article , Chuck Sherwood wrote: Would it be correct that all these phase converters that are not based on motor/generators, are unable to run more than one 3 phase device at a time. That is not correct. Rotary phase converters are often used to run multiple machines. One at a time or even more that one at a time. Agreed -- but he said "*not* based on motor/generators", which I think he intended to also exclude idlers used as rotary phase converters. The idler motor is serving both as a motor and a generator at the same time. I did not mean to exclude idlers. At the time when I asked my question, I did not understand the role of idler. Now I do understand its role, thanks to Jim Rozen's pictures. "Rotary" phase converters, build around an idler motor, can not only run more than one load motor at a time, but can even handle more load horsepower when doing so, because each load motor already running off of it contributes to the "rotary converter" effect. So, if you have a 1HP motor on your lathe, and a 1-1/2 HP motor acting as your idler, you have a greater chance of starting another machine whose motor is perhaps a 2HP rating if the lathe motor is already running. i |
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