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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#41
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Don Murray wrote:
Harold and Susan Vordos wrote: "William" wrote in message news:fQire.47092$_o.36229@attbi_s71... "Pete C." wrote in message ... My 3 phase delta 240/120 volt service was installed just 4 years ago, at my request. I did not want a wye service (for obvious reasons), and am transforming to 480V for one machine. Huh? What "obvious reasons"? 120/208 Wye service has no disadvantages that I know of. You can get 120v from any of the phases, allowing you to balance your single phase loads and single pole, two pole or three pole breakers breakers can occupy any panel position since all phases are equal to each other and to the neutral. Well there are disadvantages from the 208 voltage, a lot of motors will not run at 208 with out overheating them. And my band was blade welder didn't really like it either, had problems welding the larger blades. The oven elements also don't seem to get as hot, cloths dryer, etc..... William... Exactly! I'm still at a loss to understand why the delta system is such a problem. Seems to me the Wye system, *for a machine shop*, would be far more disadvantageous. You'd have to be completely out of your mind to request it if delta was available. Harold You're right, Harold. I think the 3 transformer delta service is the better of the two. One advantage is that when one transformer goes out a trouble shooter from the power company (me) can go out and rebuss it into an open delta and have you back up and running in 30 minutes. The two transformer open delta is only good for 86.6% of the KVA rating of the two transformers. So you might have to shed some load. You should also be able to replace the transformer in about the same time period. I watched a crew (two guys in buckets and one ground guy) change one in about 15 minutes. Even with the first guy (you) getting on the scene and then calling in for another truck to bring out the transformer while you remove the bad one it should not take very long. Pete C. |
#42
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"Pete C." wrote in message ... Don Murray wrote: Harold and Susan Vordos wrote: "William" wrote in message news:fQire.47092$_o.36229@attbi_s71... "Pete C." wrote in message ... My 3 phase delta 240/120 volt service was installed just 4 years ago, at my request. I did not want a wye service (for obvious reasons), and am transforming to 480V for one machine. Huh? What "obvious reasons"? 120/208 Wye service has no disadvantages that I know of. You can get 120v from any of the phases, allowing you to balance your single phase loads and single pole, two pole or three pole breakers breakers can occupy any panel position since all phases are equal to each other and to the neutral. Well there are disadvantages from the 208 voltage, a lot of motors will not run at 208 with out overheating them. And my band was blade welder didn't really like it either, had problems welding the larger blades. The oven elements also don't seem to get as hot, cloths dryer, etc..... William... Exactly! I'm still at a loss to understand why the delta system is such a problem. Seems to me the Wye system, *for a machine shop*, would be far more disadvantageous. You'd have to be completely out of your mind to request it if delta was available. Harold You're right, Harold. I think the 3 transformer delta service is the better of the two. One advantage is that when one transformer goes out a trouble shooter from the power company (me) can go out and rebuss it into an open delta and have you back up and running in 30 minutes. The two transformer open delta is only good for 86.6% of the KVA rating of the two transformers. So you might have to shed some load. You should also be able to replace the transformer in about the same time period. I watched a crew (two guys in buckets and one ground guy) change one in about 15 minutes. Even with the first guy (you) getting on the scene and then calling in for another truck to bring out the transformer while you remove the bad one it should not take very long. Pete C. Chuckle! You, apparently, live in town. Not only could they not replace one for me in 15 minutes, it's highly unlikely they could do so in a couple hours. It would take no less than 45 minutes for someone to respond to our remote address, then the time it would take to get a transformer on location, assuming they had one in the yard. Yeah, I know, small chance it would ever be an issue, but it's yet another one of the things that make me sure I did the right thing. I say go with the wild leg delta! In my experience, many of the older machines had motors wound for 240V, not 208V. That tells me they would be inclined to run hot. Do keep in mind I am not an electrician, so my exposure has been quite limited. Could be I'm all wet. Harold |
#43
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"Pete C." wrote in message ... Harold and Susan Vordos wrote: "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip---- That's how everything used to be and I believe both the wild leg and open delta configurations were primarily used as a way to save transformer costs. Regardless of reason, machine shops are typically provided with this service. The higher voltage is very desirable, and in some cases mandatory. I question your logic about saving transformer costs if individual machines would require buck/boost transformers. Between the area required to store them, and the increased cost of labor for installing them, seems to me it's a terrible waste of money when it can be dealt with by installing the delta system instead of the wye. The transformer cost savings was for the large oil filled cans on the pole, by using only two for open delta, or two smaller and one larger for the unbalanced wild leg. The buck/boost autotransformers are quite small and inexpensive. They are dry type autotransformers, not full isolating transformers with multiple windings so they are much smaller than you would expect for their capacity. The KVA size required for the autotransformer is not the full KVA of the load. The sizes you would need for an average machine are about shoe box size and around $150 new. Yeah, times 2 or three per machine, then the labor to install them. I think you shot yourself in the foot here, Pete. My point is that 3 phase delta is already the proper voltage----you need not find space for more electrical apparatus, nor pay for its installation. So far, I'm not convinced, and I'd refuse a wye service given a choice, which is exactly what I did when I requested my delta service. But you've overlooked the fact that it does *not* yield 240 volts, the optimum voltage for machine tools. I'm having more than a little trouble understanding why you feel delta is such a bad deal when it solves all problems aside from the wild leg issue. I can't think of one small machine shop that is wired wye------not one. Many of my friends are still in business in Utah, all of which have the delta service. Could be it's a regional thing. Dunno. How is 240v "optimum" for machine tools? A lot of machines larger than bench top size can be strapped for operation on 480v input as well. When I did CNC service, I don't recall seeing a single machine that didn't have a 480v input option. Agreed. The vast majority of the large shops in which I worked had 480 volt service. I have no idea if they were delta or wye. I would consider "optimum" voltage for a machine to be any voltage that it can be strapped for. If it was designed with those taps then it should operate just as well on any of them. I would consider optimum voltage one that, given anything but a proper match, would be higher voltage instead of lower voltage, so motors didn't run hot. You may not think that's a problem, but I can tell you from the perspective of a guy that knows how to move metal when roughing, it's damned important. It's not unusual for a machine tool to be subjected to a 125% demand on horsepower. I've seen machines that shut down because they've been ridden hot and put away wet. No thanks, no 208 voltage for me. The "optimum" voltage that you would want to use based on external factors would be one of the higher voltage options based on smaller required wire gauge, reduced voltage drop, etc. From that standpoint 208v and 240v are essentially equal. But *not* equal. If a machine has taps for both 208v and 240v then there is no advantage or disadvantage to either, only the convenience of what you have available. If there are a sufficient number of machines that can take 480v to fill a decent portion of a 480v panel then that is an even better choice. My (very limited) experience has been that motors that are capable of running both voltages are wound 230 volts. I know my Bridgeport is so wound. That means, while you're still within tolerance, the motor is still running hotter than is necessary when operated on 208V. I may be wrong, but I don't think you have the luxury of changing internal wiring to reflect 208 or 240 volts. The only changes are to accommodate higher voltage, i.e. 460 volts, in my case. It would certainly be my preference to use a few autotransformers on one or two problem machines rather than go with a wild leg system. You keep speaking of these problems, but I've had 3 phase delta systems since 1967, and aside from the one failure, which would have occurred be it delta or wye, I've never had any problems. From that I conclude that the problems, while possibly serious, are highly unlikely to plague the average person. I'm more than willing to gamble on these ethereal problems than request wye service and know for damned sure I'm going to face other problems, which I would. I get the idea you're geared to light commercial, where wye service is the norm. Machine shops do not use it----for obvious reasons. Places that have a lighting load that tends to be the largest power demand is where you find lots of wye service, at least in my experience. Wye service is indeed good for buildings with a lot of lighting load, 480/277 is particularly good for that. The main thing is that you are indicating that there is a big disadvantage to 208v vs. 240v which I just don't see. I think your making more of the difference between 208v and 240v than there is justification for. Funny, I was thinking the same about your position. I can't imagine how the things you have spoken of are not a problem, buck/boost transformers for individual machines (cost and inconvenience of placement), motors that run hotter than is necessary. The allowable voltage range for your 240/120 3ph delta wild leg service is from 220v-254v at the service entrance (from a chart referencing ANSI C84.1-1989). If the service is considered acceptable over a range of 34v I just don't see a 32V difference between services as significant. The voltage spread would, likewise be similar for 208, if not the same. It's greater than 10%, the normal tolerance for motor voltage. Am I wrong? Isn't that why newer motors are wound 230 volts? To keep them within tolerance? Wouldn't that mean that older, 240 volt motors, would be running out of tolerance if applied to 208 volt service? Large motors are built to handle widely varying power and load conditions, and power supplies for controls either have plenty of tap adjustment range for older machines, or switching supplies for newer machines that are happy on anywhere from 98v - 250v. Your motors might run a few degrees warmer but still well within their specified operating range and your controls should be perfectly happy as well. Tell my friend in Utah that he only imagined the problems he had with his CNC grinders when he moved his shop to one wired wye. You make light of it, but it was a serious problem for him. His machines wouldn't run. I do not recall how they rectified the problem, this was about 12 years ago. Basically I think the 14% or so difference is of little to no significance for 95% of the possible machines you might run, and for those few the fix is easy and inexpensive. But it *is* outside the 10% tolerance zone. I don't agree. I also don't think of buying buck/boost transformers @ a few hundred dollars as not being expensive. Especially commercially, where they *must* be installed by a licensed electrician. I can see how such an installation could turn into several hundred dollars per small machine, and in the thousands for large ones. And actually the 240V is some 9% high for the machine, as it's motor is rated for 220/440. Yeah, 9% high, and in tolerance, unlike 14% low, and out of tolerance. Funny, I get the distinct idea you think I made a mistake by installing the delta system. You couldn't be more wrong if you tried. It serves my purpose perfectly, very unlike a wye system. I think my main point is that I feel the Wye system would have served your needs equally well and would have simplified the installation by avoiding your use of separate panels for your single and three phase loads to avoid the wild leg issue. Wrong! I have *no* wild leg issues. In fact, my split panels provide a good an valuable service beyond just addressing that problem. I'm on a demand meter with my 3 phase, but not the single phase panel. The moment I go above 50 KW (my induction furnace is a 50 KW unit), I pay more for my power. The way I've wired the shop, I avoid the demand load except where absolutely necessary, which is for the 3 phase equipment. My lighting load alone could reach about 75 amps, if I was to run all my fluorescent lights at one time. Each one is individually switched at the fixture so I can use only those that are necessary. In turn, they are wired in six banks, so each series (according to shop location) can be switched at the door. My 42 position (Square D) single phase panel is all but full, without accounting for any 3 phase devices. In other words, I'd have had to install two panels, regardless. As it is, I have three, one being a 400 amp disconnect that feeds the induction furnace. I am better off for the way I've installed my service, and I still have no regrets for having selected delta. If anything, you've further convinced me I did the right thing. For that, I thank you. Harold |
#44
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Harold and Susan Vordos wrote:
"Pete C." wrote in message ... Don Murray wrote: Harold and Susan Vordos wrote: "William" wrote in message news:fQire.47092$_o.36229@attbi_s71... "Pete C." wrote in message ... My 3 phase delta 240/120 volt service was installed just 4 years ago, at my request. I did not want a wye service (for obvious reasons), and am transforming to 480V for one machine. Huh? What "obvious reasons"? 120/208 Wye service has no disadvantages that I know of. You can get 120v from any of the phases, allowing you to balance your single phase loads and single pole, two pole or three pole breakers breakers can occupy any panel position since all phases are equal to each other and to the neutral. Well there are disadvantages from the 208 voltage, a lot of motors will not run at 208 with out overheating them. And my band was blade welder didn't really like it either, had problems welding the larger blades. The oven elements also don't seem to get as hot, cloths dryer, etc..... William... Exactly! I'm still at a loss to understand why the delta system is such a problem. Seems to me the Wye system, *for a machine shop*, would be far more disadvantageous. You'd have to be completely out of your mind to request it if delta was available. Harold You're right, Harold. I think the 3 transformer delta service is the better of the two. One advantage is that when one transformer goes out a trouble shooter from the power company (me) can go out and rebuss it into an open delta and have you back up and running in 30 minutes. The two transformer open delta is only good for 86.6% of the KVA rating of the two transformers. So you might have to shed some load. You should also be able to replace the transformer in about the same time period. I watched a crew (two guys in buckets and one ground guy) change one in about 15 minutes. Even with the first guy (you) getting on the scene and then calling in for another truck to bring out the transformer while you remove the bad one it should not take very long. Pete C. Chuckle! You, apparently, live in town. Not only could they not replace one for me in 15 minutes, it's highly unlikely they could do so in a couple hours. It would take no less than 45 minutes for someone to respond to our remote address, then the time it would take to get a transformer on location, assuming they had one in the yard. That case was indeed in town and it was a planned replacement. However, if you give them sufficient information when you log the trouble call I see no reason they couldn't have the correct transformer with them when they come out. Given the stock yards I've seen I think it's pretty unlikely that they would not have a suitable replacement on hand. So 15 min to replace + travel time to get there. Yeah, I know, small chance it would ever be an issue, but it's yet another one of the things that make me sure I did the right thing. I say go with the wild leg delta! In my experience, many of the older machines had motors wound for 240V, not 208V. That tells me they would be inclined to run hot. Do keep in mind I am not an electrician, so my exposure has been quite limited. Could be I'm all wet. Well, the motor (original) on my old old 1J Bridgeport is 220/440 rated. Looking at the Grainger and Baldor sites I was not able to find any 240V rated motors. I suspect you'll find the machines have 220V or 230V rated motors. The difference in current draw between operation at 208V and 240V is quite small and only a portion of that difference would be dissipated as heat. For a 2 HP Baldor motor I looked at the total difference was 104W and even if all of that was dissipated as heat across the 60# motors frame it would be pretty insignificant. Most all motors are going to run hot on continuous duty and that's why they have the different insulation classes. If the motor runs 4 or 5 degrees hotter on the lower voltage it's not very significant. Pete C. |
#45
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Harold and Susan Vordos wrote:
"Pete C." wrote in message ... Harold and Susan Vordos wrote: "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip---- That's how everything used to be and I believe both the wild leg and open delta configurations were primarily used as a way to save transformer costs. Regardless of reason, machine shops are typically provided with this service. The higher voltage is very desirable, and in some cases mandatory. I question your logic about saving transformer costs if individual machines would require buck/boost transformers. Between the area required to store them, and the increased cost of labor for installing them, seems to me it's a terrible waste of money when it can be dealt with by installing the delta system instead of the wye. The transformer cost savings was for the large oil filled cans on the pole, by using only two for open delta, or two smaller and one larger for the unbalanced wild leg. The buck/boost autotransformers are quite small and inexpensive. They are dry type autotransformers, not full isolating transformers with multiple windings so they are much smaller than you would expect for their capacity. The KVA size required for the autotransformer is not the full KVA of the load. The sizes you would need for an average machine are about shoe box size and around $150 new. Yeah, times 2 or three per machine, then the labor to install them. I think you shot yourself in the foot here, Pete. My point is that 3 phase delta is already the proper voltage----you need not find space for more electrical apparatus, nor pay for its installation. So far, I'm not convinced, and I'd refuse a wye service given a choice, which is exactly what I did when I requested my delta service. For the perhaps 5% of machines that might actually require them? A smaller shop may well not have a single machine that legitimately required the boost transformers. But you've overlooked the fact that it does *not* yield 240 volts, the optimum voltage for machine tools. I'm having more than a little trouble understanding why you feel delta is such a bad deal when it solves all problems aside from the wild leg issue. I can't think of one small machine shop that is wired wye------not one. Many of my friends are still in business in Utah, all of which have the delta service. Could be it's a regional thing. Dunno. How is 240v "optimum" for machine tools? A lot of machines larger than bench top size can be strapped for operation on 480v input as well. When I did CNC service, I don't recall seeing a single machine that didn't have a 480v input option. Agreed. The vast majority of the large shops in which I worked had 480 volt service. I have no idea if they were delta or wye. I would consider "optimum" voltage for a machine to be any voltage that it can be strapped for. If it was designed with those taps then it should operate just as well on any of them. I would consider optimum voltage one that, given anything but a proper match, would be higher voltage instead of lower voltage, so motors didn't run hot. You may not think that's a problem, but I can tell you from the perspective of a guy that knows how to move metal when roughing, it's damned important. It's not unusual for a machine tool to be subjected to a 125% demand on horsepower. I've seen machines that shut down because they've been ridden hot and put away wet. No thanks, no 208 voltage for me. I think you're under the impression that a motor will run hotter if it's strapped for it's lower voltage rating. A motor should run at the same temp for the same load and duty cycle conditions when operated at any voltage it can be strapped for. Operation at the higher voltage setting is for the benefit of smaller wire gauge to feed the motor, lower voltage loss on those wires and smaller switch gear to service it, not for the benefit of the motor. If you are pushing your machines past their continuous ratings for significant amounts of time you should fully expect them to shut down on you. Brief excursions past the continuous rating are ok, but sustained use there is not. The "optimum" voltage that you would want to use based on external factors would be one of the higher voltage options based on smaller required wire gauge, reduced voltage drop, etc. From that standpoint 208v and 240v are essentially equal. But *not* equal. Correct 208V /= 240V. However the ~ 14% difference is not significant from a practical standpoint. With either 208V or 240V vs. 120V you're getting the benefits of the smaller wire and switch gear requirements and lower voltage drop. If a machine has taps for both 208v and 240v then there is no advantage or disadvantage to either, only the convenience of what you have available. If there are a sufficient number of machines that can take 480v to fill a decent portion of a 480v panel then that is an even better choice. My (very limited) experience has been that motors that are capable of running both voltages are wound 230 volts. I know my Bridgeport is so wound. That means, while you're still within tolerance, the motor is still running hotter than is necessary when operated on 208V. I may be wrong, but I don't think you have the luxury of changing internal wiring to reflect 208 or 240 volts. The only changes are to accommodate higher voltage, i.e. 460 volts, in my case. My Bridgeport motor is 220/440. It would certainly be my preference to use a few autotransformers on one or two problem machines rather than go with a wild leg system. You keep speaking of these problems, but I've had 3 phase delta systems since 1967, and aside from the one failure, which would have occurred be it delta or wye, I've never had any problems. From that I conclude that the problems, while possibly serious, are highly unlikely to plague the average person. I'm more than willing to gamble on these ethereal problems than request wye service and know for damned sure I'm going to face other problems, which I would. I get the idea you're geared to light commercial, where wye service is the norm. Machine shops do not use it----for obvious reasons. Places that have a lighting load that tends to be the largest power demand is where you find lots of wye service, at least in my experience. Wye service is indeed good for buildings with a lot of lighting load, 480/277 is particularly good for that. The main thing is that you are indicating that there is a big disadvantage to 208v vs. 240v which I just don't see. I think your making more of the difference between 208v and 240v than there is justification for. Funny, I was thinking the same about your position. I can't imagine how the things you have spoken of are not a problem, buck/boost transformers for individual machines (cost and inconvenience of placement), motors that run hotter than is necessary. Again you're assuming that most machines will require the transformers, which is not the case. The hotter part is a small amount, perhaps significant for a big shop in the desert, but not significant in most cases. The allowable voltage range for your 240/120 3ph delta wild leg service is from 220v-254v at the service entrance (from a chart referencing ANSI C84.1-1989). If the service is considered acceptable over a range of 34v I just don't see a 32V difference between services as significant. The voltage spread would, likewise be similar for 208, if not the same. It's greater than 10%, the normal tolerance for motor voltage. Am I wrong? Isn't that why newer motors are wound 230 volts? To keep them within tolerance? Wouldn't that mean that older, 240 volt motors, would be running out of tolerance if applied to 208 volt service? I think that any older motors that are truly rated for 240V are also old enough to be overbuilt beasts from the days when the line regulation was nowhere near where it is today and consequently would likely not care about running at 208V which is likely what they saw anyway on old services with significant voltage drops within the building. Large motors are built to handle widely varying power and load conditions, and power supplies for controls either have plenty of tap adjustment range for older machines, or switching supplies for newer machines that are happy on anywhere from 98v - 250v. Your motors might run a few degrees warmer but still well within their specified operating range and your controls should be perfectly happy as well. Tell my friend in Utah that he only imagined the problems he had with his CNC grinders when he moved his shop to one wired wye. You make light of it, but it was a serious problem for him. His machines wouldn't run. I do not recall how they rectified the problem, this was about 12 years ago. By changing the taps on the control transformers within the machines and adjusting the set points for the motor starters? Basically I think the 14% or so difference is of little to no significance for 95% of the possible machines you might run, and for those few the fix is easy and inexpensive. But it *is* outside the 10% tolerance zone. I don't agree. I also don't think of buying buck/boost transformers @ a few hundred dollars as not being expensive. Especially commercially, where they *must* be installed by a licensed electrician. I can see how such an installation could turn into several hundred dollars per small machine, and in the thousands for large ones. Actually if they are installed integrally to the machine then they would bypass any licensing requirement. Licensing requirements do not extend past the power input terminals on the machine. Bolt the boost transformers to the side of the control cabinet and run all the connections inside the cabinet and they become part of the machine tool. And actually the 240V is some 9% high for the machine, as it's motor is rated for 220/440. Yeah, 9% high, and in tolerance, unlike 14% low, and out of tolerance. Funny, I get the distinct idea you think I made a mistake by installing the delta system. You couldn't be more wrong if you tried. It serves my purpose perfectly, very unlike a wye system. I think my main point is that I feel the Wye system would have served your needs equally well and would have simplified the installation by avoiding your use of separate panels for your single and three phase loads to avoid the wild leg issue. Wrong! I have *no* wild leg issues. In fact, my split panels provide a good an valuable service beyond just addressing that problem. I'm on a demand meter with my 3 phase, but not the single phase panel. The moment I go above 50 KW (my induction furnace is a 50 KW unit), I pay more for my power. The way I've wired the shop, I avoid the demand load except where absolutely necessary, which is for the 3 phase equipment. My lighting load alone could reach about 75 amps, if I was to run all my fluorescent lights at one time. Each one is individually switched at the fixture so I can use only those that are necessary. In turn, they are wired in six banks, so each series (according to shop location) can be switched at the door. And you're paying extra for the second service (meter) vs. a single meter if you used Wye service. The whole peak meter thing can get pretty hinky, particularly when it is based on rolling averages, not hard setpoints. If it's based on rolling averages then a consistent lighting load has little effect. You really have to analyze your loads to see what is best. My 42 position (Square D) single phase panel is all but full, without accounting for any 3 phase devices. In other words, I'd have had to install two panels, regardless. As it is, I have three, one being a 400 amp disconnect that feeds the induction furnace. I am better off for the way I've installed my service, and I still have no regrets for having selected delta. If anything, you've further convinced me I did the right thing. For that, I thank you. If you've got individual 50KW loads you may well be big enough to have benefited from 480V service. Pete C. |
#46
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"Harold and Susan Vordos" wrote in message ... "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip---- That's how everything used to be and I believe both the wild leg and open delta configurations were primarily used as a way to save transformer costs. Regardless of reason, machine shops are typically provided with this service. The higher voltage is very desirable, and in some cases mandatory. I question your logic about saving transformer costs if individual machines would require buck/boost transformers. Between the area required to store them, and the increased cost of labor for installing them, seems to me it's a terrible waste of money when it can be dealt with by installing the delta system instead of the wye. It's the power co that saves on the transformers, not you. You get to supply the buck/boost transformers if you want them! Also the buck/boost transformers are on your side it the meter so you get to pay to keep them warm ( this is not as bad as keeping the big ones hot though) William.... |
#47
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"Pete C." wrote in message ... Harold and Susan Vordos wrote: "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip---- I think you're under the impression that a motor will run hotter if it's strapped for it's lower voltage rating. A motor should run at the same temp for the same load and duty cycle conditions when operated at any voltage it can be strapped for. I fully agree, but I have no motors that can be strapped for 208. As I said, my Bridgeport is wound for 230. I don't recall what the Graziano demands, and the motor is internal--not readily available. I just know that it runs well on 240, so why risk anything? The induction furnace is wired 220/440. It would be within range, but the huge amperage demand makes running at a slightly higher voltage an advantage over running lower. Not necessarily for wire size, but, again, for heat control. Operation at the higher voltage setting is for the benefit of smaller wire gauge to feed the motor, lower voltage loss on those wires and smaller switch gear to service it, not for the benefit of the motor. I understand that, but the cooler operation is certainly a benefit. Again you're assuming that most machines will require the transformers, which is not the case. The hotter part is a small amount, perhaps significant for a big shop in the desert, but not significant in most cases. No, what I'm assuming is that the majority of the machines would be running in the tolerance zone, unnecessarily. Given a choice, why would I want any of my machines to run under voltage? Even within tolerance? Over voltage is far superior to under voltage if one must deviate from the ideal. I think that any older motors that are truly rated for 240V are also old enough to be overbuilt beasts from the days when the line regulation was nowhere near where it is today and consequently would likely not care about running at 208V which is likely what they saw anyway on old services with significant voltage drops within the building. Could be, but I'd not be willing to gamble on it. Good example is the induction furnace, although it's not one of the machines that falls out of the tolerance zone (220/440 in this case). The motor generator weighs almost three tons, and is water cooled, not fan cooled. That means it has the potential to run hotter than I would like because it relies on heat conduction with small coils of circulating water wrapped around the exterior of the assembly. Adding any unnecessary heat to its operation would not be in my best interest, especially if it had the potential for failure. I can't speak for you, but I couldn't afford to pay for a rewind on something of that magnitude. Tell my friend in Utah that he only imagined the problems he had with his CNC grinders when he moved his shop to one wired wye. You make light of it, but it was a serious problem for him. His machines wouldn't run. I do not recall how they rectified the problem, this was about 12 years ago. By changing the taps on the control transformers within the machines and adjusting the set points for the motor starters? Dunno. As I said, I don't recall, but he has since built his own place and has it wired according to his needs. Can't help but think it's delta, but I couldn't swear it is. For all I know, he may be wired 480. I'll try to remember to ask him the next time we talk on the phone. Actually if they are installed integrally to the machine then they would bypass any licensing requirement. Licensing requirements do not extend past the power input terminals on the machine. Bolt the boost transformers to the side of the control cabinet and run all the connections inside the cabinet and they become part of the machine tool. All well and good if you choose to use a wye service, but I chose to eliminate that problem. I'm as happy as if I had good sense. Even *if* one can get around the licensed electrician, you still face the cost of the buck/boost transformers, which, at a minimum, would cost at least $300 per machine, assuming you could get away with two instead of three. You also have the cost of mounting them, and the inconvenience of them being in place, adding considerably to the bulk of the machine, with no benefits. No thanks. I think my main point is that I feel the Wye system would have served your needs equally well and would have simplified the installation by avoiding your use of separate panels for your single and three phase loads to avoid the wild leg issue. Wrong! I have *no* wild leg issues. In fact, my split panels provide a good an valuable service beyond just addressing that problem. I'm on a demand meter with my 3 phase, but not the single phase panel. The moment I go above 50 KW (my induction furnace is a 50 KW unit), I pay more for my power. The way I've wired the shop, I avoid the demand load except where absolutely necessary, which is for the 3 phase equipment. My lighting load alone could reach about 75 amps, if I was to run all my fluorescent lights at one time. Each one is individually switched at the fixture so I can use only those that are necessary. In turn, they are wired in six banks, so each series (according to shop location) can be switched at the door. And you're paying extra for the second service (meter) vs. a single meter if you used Wye service. The whole peak meter thing can get pretty hinky, particularly when it is based on rolling averages, not hard setpoints. If it's based on rolling averages then a consistent lighting load has little effect. You really have to analyze your loads to see what is best. Nope! Wrong again. I am paying for two services in spite of my choice of delta over wye. *ANY* 3 phase service is considered industrial where we live. Had I run everything through the CT can, avoiding the meter base, I'd be paying for my power at a higher rate because I'd exceed the maximum (demand meter). Our meter base is a 375 amp unit, so we feed both the shop and the house from it, at a residential rate. It's simple------if I wanted three phase service, and I did, I had to pay for two services, like it or not (and I don't). As much as I may not like the cost, I'm very happy to have the convenience. I explored the idea of phase converters and quickly dismissed the idea. Way too expensive, considering the load I had with the induction furnace. I had two choices had I chosen phase converters-----buy one huge unit and pay for the idling current endlessly, or buy a few small units and bring them online as needed, still paying for idling current. It was cheaper, and far more convenient, to pay for three phase service. To the best of my knowledge, I chose the right service for my needs. Considering I have nothing that is wired for 208, nor can any of it be rewired to accommodate that voltage, I sure as hell didn't want it in the shop. If industry today is headed that direction, and machine tools are so wired, that's a whole different situation, and I'd have no quarrel with the choice. With the machines I have, that wasn't one of the options, and I sure as hell wasn't going to spring for transformers that weren't necessary, not when all I had to do is request the right service. If you've got individual 50KW loads you may well be big enough to have benefited from 480V service. Again, a judgment call. I have one device with that load. Why would I pay for 480 service, add an additional panel, then transform for everything else? Personally, I think I made some excellent choices. Everything I have runs as it should, and I haven't filled the shop with unnecessary transformers. Idling current alone would have been expensive in the long haul had I chosen that path. I have only one machine that *requires* 480 volts, a German made universal cylindrical grinder, which cannot be strapped for 240 volts, or anything within reason. The only time the transformer will be energized is when I use the machine. There will be no idling consumption otherwise, so I won't be paying for making heat. Regardless of your opinion, I feel I've done a damned good job of addressing the problems at hand. Your bias against delta service seems to be a much greater stumbling block for you than my choices are for me. Very strange, Pete. However, I think if you visited my shop and observed how nicely it all has come together, I think you might find yourself agreeing that I did the right thing. :-) Harold |
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"William" wrote in message news:gRDre.49036$x96.9997@attbi_s72... snip-- It's the power co that saves on the transformers, not you. You get to supply the buck/boost transformers if you want them! Also the buck/boost transformers are on your side it the meter so you get to pay to keep them warm ( this is not as bad as keeping the big ones hot though) William.... Yep, which is just one more reason to avoid them if possible. I did!! Harold |
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Harold and Susan Vordos wrote:
snip And you're paying extra for the second service (meter) vs. a single meter if you used Wye service. The whole peak meter thing can get pretty hinky, particularly when it is based on rolling averages, not hard setpoints. If it's based on rolling averages then a consistent lighting load has little effect. You really have to analyze your loads to see what is best. Nope! Wrong again. I am paying for two services in spite of my choice of delta over wye. *ANY* 3 phase service is considered industrial where we live. Had I run everything through the CT can, avoiding the meter base, I'd be paying for my power at a higher rate because I'd exceed the maximum (demand meter). Our meter base is a 375 amp unit, so we feed both the shop and the house from it, at a residential rate. It's simple------if I wanted three phase service, and I did, I had to pay for two services, like it or not (and I don't). As much as I may not like the cost, I'm very happy to have the convenience. I explored the idea of phase converters and quickly dismissed the idea. Way too expensive, considering the load I had with the induction furnace. I had two choices had I chosen phase converters-----buy one huge unit and pay for the idling current endlessly, or buy a few small units and bring them online as needed, still paying for idling current. It was cheaper, and far more convenient, to pay for three phase service. Interesting. In my former area commercial rates were lower per KWH than residential rates. As long as you could manage your loads well enough to avoid problems due to peak metering you could get better rates by hanging your house off of your commercial service. That induction furnace of yours seems to be the biggest issue no mater which way you go. Such a massive single load makes it difficult to optimize for peak metering. As for phase converters, for manual machines I'd use inverter drives instead since their costs have become quite reasonable and they don't have an idle current issue. For CNC machines in many cases you could modify them to run from mostly single phase power and a smaller inverter or rotary phase converter. Not real practical for multiple machines in a larger shop, but a workable route for a couple machines in a home shop. To the best of my knowledge, I chose the right service for my needs. Considering I have nothing that is wired for 208, nor can any of it be rewired to accommodate that voltage, I sure as hell didn't want it in the shop. If industry today is headed that direction, and machine tools are so wired, that's a whole different situation, and I'd have no quarrel with the choice. With the machines I have, that wasn't one of the options, and I sure as hell wasn't going to spring for transformers that weren't necessary, not when all I had to do is request the right service. It's likely that the potential issues diminish as the equipment gets newer. If you've got individual 50KW loads you may well be big enough to have benefited from 480V service. Again, a judgment call. I have one device with that load. Why would I pay for 480 service, add an additional panel, then transform for everything else? Personally, I think I made some excellent choices. Everything I have runs as it should, and I haven't filled the shop with unnecessary transformers. Idling current alone would have been expensive in the long haul had I chosen that path. I have only one machine that *requires* 480 volts, a German made universal cylindrical grinder, which cannot be strapped for 240 volts, or anything within reason. The only time the transformer will be energized is when I use the machine. There will be no idling consumption otherwise, so I won't be paying for making heat. Regardless of your opinion, I feel I've done a damned good job of addressing the problems at hand. Your bias against delta service seems to be a much greater stumbling block for you than my choices are for me. Very strange, Pete. However, I think if you visited my shop and observed how nicely it all has come together, I think you might find yourself agreeing that I did the right thing. :-) If you've only got one huge load then 480 service is probably not worthwhile. Stepping up for the one problem grinder makes sense, just as adding boost transformers makes sense if it's only a machine or two that need them. Remember, I'm not biased against delta service, I'm biased against wild leg delta service, two different things. I'm sure your shop is quite nice, it sounds like it's well equipped. Were I planning a new shop with the full list of equipment to be in it, their specs, etc. I might well decide on a service configuration that included delta service for the machines. I would just avoid a service configuration that included a wild leg. Pete C. |
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"Pete C." wrote in message ... Harold and Susan Vordos wrote: snip--- To the best of my knowledge, I chose the right service for my needs. Considering I have nothing that is wired for 208, nor can any of it be rewired to accommodate that voltage, I sure as hell didn't want it in the shop. If industry today is headed that direction, and machine tools are so wired, that's a whole different situation, and I'd have no quarrel with the choice. With the machines I have, that wasn't one of the options, and I sure as hell wasn't going to spring for transformers that weren't necessary, not when all I had to do is request the right service. It's likely that the potential issues diminish as the equipment gets newer. I certainly get that idea-----even PUD was somewhat surprised that I wanted the delta service. Stepping up for the one problem grinder makes sense, just as adding boost transformers makes sense if it's only a machine or two that need them. I don't agree on the boost transformers, not when I'm as pleased as I am to have the service I have. As I stated, I don't consider buying boost transformers to be a bargain, nor would I like feeding them on a continual basis, in spite of the fact that we pay only $.0445 kwh for our power. I have yet to discover one thing about my service that displeases me, and I've had 3 phase delta since 1967. One of us is nuts! :-) Remember, I'm not biased against delta service, I'm biased against wild leg delta service, two different things. You keep saying that, as if there's other types. I've heard of a corner grounded delta (but don't understand how it relates to voltage), but as far as I know, they all have a wild leg if you shoot for 120V. Is there something I don't know or understand? The moment you introduce the neutral, seems to me you're bound to have only two phases that yield 120V unless your wired wye. Were I planning a new shop with the full list of equipment to be in it, their specs, etc. I might well decide on a service configuration that included delta service for the machines. I would just avoid a service configuration that included a wild leg. OK---fill me in, then. What type of service would it be? Strictly 240 V? That's what I have now. I do *not* use my 3 phase for single phase service*, although when I wire my mill permanently, I will have single phase for the power feed and work light, but only there. I'll do that so I can keep the wires away from the bottom of the machine. I have the box overhead, almost directly over the motor on the mill. 12' ceiling. You can do that when you have a 5 wire system. Everything else is strictly 3 wires, plus ground. Do you still have heartburn over my wiring? *The same phases that constitute my A & C phases in the 3 phase panel feed my single phase panel, although through separate lines and conduit, from the pole. Want to see a pic? Harold |
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"Harold and Susan Vordos" wrote in message ... "Pete C." wrote in message ... If you've got individual 50KW loads you may well be big enough to have benefited from 480V service. Again, a judgment call. I have one device with that load. Why would I pay for 480 service, add an additional panel, then transform for everything else? Personally, I think I made some excellent choices. Everything I have runs as it should, and I haven't filled the shop with unnecessary transformers. Idling current alone would have been expensive in the long haul had I chosen that path. I have only one machine that *requires* 480 volts, a German made universal cylindrical grinder, which cannot be strapped for 240 volts, or anything within reason. The only time the transformer will be energized is when I use the machine. There will be no idling consumption otherwise, so I won't be paying for making heat. Regardless of your opinion, I feel I've done a damned good job of addressing the problems at hand. Your bias against delta service seems to be a much greater stumbling block for you than my choices are for me. Very strange, Pete. However, I think if you visited my shop and observed how nicely it all has come together, I think you might find yourself agreeing that I did the right thing. :-) Well since you are already running a separate service for the single phase, the 480 would have been the best for you. You don't need any transformers for the 480 service and you haven't mentioned any 3 phase equipment that requires 240 volts only. Also if you really have 75 amps of florescent lights (That's TONS of amps for lighting. Do you use sun glasses in side?? :-) you could have run all that from a 20 amp 277 breaker if you had a 480 wye setup! Much cheaper for the wire on the 50kw load on the furnace and smaller contactors and stuff on all other wires too.... William.... Harold |
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"William" wrote in message news:8FQre.53257$_o.38737@attbi_s71... "Harold and Susan Vordos" wrote in message ... "Pete C." wrote in message ... If you've got individual 50KW loads you may well be big enough to have benefited from 480V service. Again, a judgment call. I have one device with that load. Why would I pay for 480 service, add an additional panel, then transform for everything else? Personally, I think I made some excellent choices. Everything I have runs as it should, and I haven't filled the shop with unnecessary transformers. Idling current alone would have been expensive in the long haul had I chosen that path. I have only one machine that *requires* 480 volts, a German made universal cylindrical grinder, which cannot be strapped for 240 volts, or anything within reason. The only time the transformer will be energized is when I use the machine. There will be no idling consumption otherwise, so I won't be paying for making heat. Regardless of your opinion, I feel I've done a damned good job of addressing the problems at hand. Your bias against delta service seems to be a much greater stumbling block for you than my choices are for me. Very strange, Pete. However, I think if you visited my shop and observed how nicely it all has come together, I think you might find yourself agreeing that I did the right thing. :-) Well since you are already running a separate service for the single phase, the 480 would have been the best for you. You don't need any transformers for the 480 service and you haven't mentioned any 3 phase equipment that requires 240 volts only. Also if you really have 75 amps of florescent lights (That's TONS of amps for lighting. Do you use sun glasses in side?? :-) you could have run all that from a 20 amp 277 breaker if you had a 480 wye setup! Much cheaper for the wire on the 50kw load on the furnace and smaller contactors and stuff on all other wires too.... William.... Yeah, but one fly in the ointment. I own a 23 KW heat treat furnace that is wired 208 volts, with a control transformer that has taps for other voltages. According to McEngelvan, I can simply change the lead for controls and get better service, considering the coils are actually rated for 240 volts. I have yet to do it because it's not set up at this point in time. The size of the transformer for something that large would have been somewhat discouraging for me, although I think that all my equipment, otherwise, could be wired for 460/480 volts. I had to make a decision, and feel that, considering I'm not well versed in electricity, I had to do what was most comfortable for me, which would be to work with a voltage that I had worked before. I think, under the circumstances, I made the right decision, although the 400 amp Square D (disconnect) switch for the induction furnace wasn't cheap at just over $600. I still have to buy the fuses. The shop isn't fully functional at this point due to our living in it while we're building our house. No need to set up things that I can't use at the moment. Harold |
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"William" wrote in message news:gRDre.49036$x96.9997@attbi_s72... "Harold and Susan Vordos" wrote in message ... "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip---- That's how everything used to be and I believe both the wild leg and open delta configurations were primarily used as a way to save transformer costs. Regardless of reason, machine shops are typically provided with this service. The higher voltage is very desirable, and in some cases mandatory. I question your logic about saving transformer costs if individual machines would require buck/boost transformers. Between the area required to store them, and the increased cost of labor for installing them, seems to me it's a terrible waste of money when it can be dealt with by installing the delta system instead of the wye. It's the power co that saves on the transformers, not you. You get to supply the buck/boost transformers if you want them! Also the buck/boost transformers are on your side it the meter so you get to pay to keep them warm ( this is not as bad as keeping the big ones hot though) William.... Actually, in this instance, I paid for the transformers as a part of the cost of having the service installed. It had nothing to do with my decision to use a delta service, however. Strangely, in Utah, my second service, which was three phase delta to our house, the power company started off playing hardball with me. They said the cost would be prohibitive, if they would supply it, but they wouldn't. Having already been through something similar with them once before, I very calmly explained to the clerk that if I didn't get satisfaction, my next stop would be the public services commission, where I'd file a complaint against the company. At that time (and perhaps still) they were a monopoly, and were bound to provide that which the customer needed. Interestingly, it suddenly went from "you can't have it, but it would be expensive if you could" to "no problem, and we can probably provide it free of charge, providing you sign a contract that guarantees a specific amount of use". It ended up costing us nothing to have it installed. It was also 3 phase delta, 240 volts. They had to install two poles, and, naturally, three transformers. It was not an open delta. Harold |
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Harold and Susan Vordos wrote:
s "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip--- To the best of my knowledge, I chose the right service for my needs. Considering I have nothing that is wired for 208, nor can any of it be rewired to accommodate that voltage, I sure as hell didn't want it in the shop. If industry today is headed that direction, and machine tools are so wired, that's a whole different situation, and I'd have no quarrel with the choice. With the machines I have, that wasn't one of the options, and I sure as hell wasn't going to spring for transformers that weren't necessary, not when all I had to do is request the right service. It's likely that the potential issues diminish as the equipment gets newer. I certainly get that idea-----even PUD was somewhat surprised that I wanted the delta service. Stepping up for the one problem grinder makes sense, just as adding boost transformers makes sense if it's only a machine or two that need them. I don't agree on the boost transformers, not when I'm as pleased as I am to have the service I have. As I stated, I don't consider buying boost transformers to be a bargain, nor would I like feeding them on a continual basis, in spite of the fact that we pay only $.0445 kwh for our power. I have yet to discover one thing about my service that displeases me, and I've had 3 phase delta since 1967. One of us is nuts! :-) Remember, I'm not biased against delta service, I'm biased against wild leg delta service, two different things. You keep saying that, as if there's other types. I've heard of a corner grounded delta (but don't understand how it relates to voltage), but as far as I know, they all have a wild leg if you shoot for 120V. Is there something I don't know or understand? The moment you introduce the neutral, seems to me you're bound to have only two phases that yield 120V unless your wired wye. A pure delta service does not have a neutral at all. There is no 120v on it, only 240v phase to phase. The corner ground is strictly for safety purposes to limit the relative voltage from any phase to ground. This can make that phase look superficially like a neutral, but it is not. Were I planning a new shop with the full list of equipment to be in it, their specs, etc. I might well decide on a service configuration that included delta service for the machines. I would just avoid a service configuration that included a wild leg. OK---fill me in, then. What type of service would it be? Strictly 240 V? That's what I have now. I do *not* use my 3 phase for single phase service*, although when I wire my mill permanently, I will have single phase for the power feed and work light, but only there. I'll do that so I can keep the wires away from the bottom of the machine. I have the box overhead, almost directly over the motor on the mill. 12' ceiling. You can do that when you have a 5 wire system. Everything else is strictly 3 wires, plus ground. Do you still have heartburn over my wiring? *The same phases that constitute my A & C phases in the 3 phase panel feed my single phase panel, although through separate lines and conduit, from the pole. Want to see a pic? How are you going to wire the mill? Separate conduit from each panel to separate boxes overhead and separate drops to the mill head and the light / power feed? Is the neutral present in your three phase panel so you can do a single feed from there? You can't or at least shouldn't (I'd have to look in the code book) combine circuits fed from separate breakers in separate panels in a single conduit run to the mill. For the mill I would likely feed it strictly three phase and locally derive the 120v with a small transformer. Of course I got about a dozen 1 KVA 240/480 x 120/240 transformers for about $10 each brand new so that biases the economics a bit. Pete C. |
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Harold and Susan Vordos wrote:
s "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip--- To the best of my knowledge, I chose the right service for my needs. Considering I have nothing that is wired for 208, nor can any of it be rewired to accommodate that voltage, I sure as hell didn't want it in the shop. If industry today is headed that direction, and machine tools are so wired, that's a whole different situation, and I'd have no quarrel with the choice. With the machines I have, that wasn't one of the options, and I sure as hell wasn't going to spring for transformers that weren't necessary, not when all I had to do is request the right service. It's likely that the potential issues diminish as the equipment gets newer. I certainly get that idea-----even PUD was somewhat surprised that I wanted the delta service. Stepping up for the one problem grinder makes sense, just as adding boost transformers makes sense if it's only a machine or two that need them. I don't agree on the boost transformers, not when I'm as pleased as I am to have the service I have. As I stated, I don't consider buying boost transformers to be a bargain, nor would I like feeding them on a continual basis, in spite of the fact that we pay only $.0445 kwh for our power. I have yet to discover one thing about my service that displeases me, and I've had 3 phase delta since 1967. One of us is nuts! :-) Remember, I'm not biased against delta service, I'm biased against wild leg delta service, two different things. You keep saying that, as if there's other types. I've heard of a corner grounded delta (but don't understand how it relates to voltage), but as far as I know, they all have a wild leg if you shoot for 120V. Is there something I don't know or understand? The moment you introduce the neutral, seems to me you're bound to have only two phases that yield 120V unless your wired wye. A pure delta service does not have a neutral at all. There is no 120v on it, only 240v phase to phase. The corner ground is strictly for safety purposes to limit the relative voltage from any phase to ground. This can make that phase look superficially like a neutral, but it is not. Were I planning a new shop with the full list of equipment to be in it, their specs, etc. I might well decide on a service configuration that included delta service for the machines. I would just avoid a service configuration that included a wild leg. OK---fill me in, then. What type of service would it be? Strictly 240 V? That's what I have now. I do *not* use my 3 phase for single phase service*, although when I wire my mill permanently, I will have single phase for the power feed and work light, but only there. I'll do that so I can keep the wires away from the bottom of the machine. I have the box overhead, almost directly over the motor on the mill. 12' ceiling. You can do that when you have a 5 wire system. Everything else is strictly 3 wires, plus ground. Do you still have heartburn over my wiring? *The same phases that constitute my A & C phases in the 3 phase panel feed my single phase panel, although through separate lines and conduit, from the pole. Want to see a pic? How are you going to wire the mill? Separate conduit from each panel to separate boxes overhead and separate drops to the mill head and the light / power feed? Is the neutral present in your three phase panel so you can do a single feed from there? You can't or at least shouldn't (I'd have to look in the code book) combine circuits fed from separate breakers in separate panels in a single conduit run to the mill. For the mill I would likely feed it strictly three phase and locally derive the 120v with a small transformer. Of course I got about a dozen 1 KVA 240/480 x 120/240 transformers for about $10 each brand new so that biases the economics a bit. Pete C. |
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Harold and Susan Vordos wrote:
s "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip--- To the best of my knowledge, I chose the right service for my needs. Considering I have nothing that is wired for 208, nor can any of it be rewired to accommodate that voltage, I sure as hell didn't want it in the shop. If industry today is headed that direction, and machine tools are so wired, that's a whole different situation, and I'd have no quarrel with the choice. With the machines I have, that wasn't one of the options, and I sure as hell wasn't going to spring for transformers that weren't necessary, not when all I had to do is request the right service. It's likely that the potential issues diminish as the equipment gets newer. I certainly get that idea-----even PUD was somewhat surprised that I wanted the delta service. Stepping up for the one problem grinder makes sense, just as adding boost transformers makes sense if it's only a machine or two that need them. I don't agree on the boost transformers, not when I'm as pleased as I am to have the service I have. As I stated, I don't consider buying boost transformers to be a bargain, nor would I like feeding them on a continual basis, in spite of the fact that we pay only $.0445 kwh for our power. I have yet to discover one thing about my service that displeases me, and I've had 3 phase delta since 1967. One of us is nuts! :-) Remember, I'm not biased against delta service, I'm biased against wild leg delta service, two different things. You keep saying that, as if there's other types. I've heard of a corner grounded delta (but don't understand how it relates to voltage), but as far as I know, they all have a wild leg if you shoot for 120V. Is there something I don't know or understand? The moment you introduce the neutral, seems to me you're bound to have only two phases that yield 120V unless your wired wye. A pure delta service does not have a neutral at all. There is no 120v on it, only 240v phase to phase. The corner ground is strictly for safety purposes to limit the relative voltage from any phase to ground. This can make that phase look superficially like a neutral, but it is not. Were I planning a new shop with the full list of equipment to be in it, their specs, etc. I might well decide on a service configuration that included delta service for the machines. I would just avoid a service configuration that included a wild leg. OK---fill me in, then. What type of service would it be? Strictly 240 V? That's what I have now. I do *not* use my 3 phase for single phase service*, although when I wire my mill permanently, I will have single phase for the power feed and work light, but only there. I'll do that so I can keep the wires away from the bottom of the machine. I have the box overhead, almost directly over the motor on the mill. 12' ceiling. You can do that when you have a 5 wire system. Everything else is strictly 3 wires, plus ground. Do you still have heartburn over my wiring? *The same phases that constitute my A & C phases in the 3 phase panel feed my single phase panel, although through separate lines and conduit, from the pole. Want to see a pic? How are you going to wire the mill? Separate conduit from each panel to separate boxes overhead and separate drops to the mill head and the light / power feed? Is the neutral present in your three phase panel so you can do a single feed from there? You can't or at least shouldn't (I'd have to look in the code book) combine circuits fed from separate breakers in separate panels in a single conduit run to the mill. For the mill I would likely feed it strictly three phase and locally derive the 120v with a small transformer. Of course I got about a dozen 1 KVA 240/480 x 120/240 transformers for about $10 each brand new so that biases the economics a bit. Pete C. |
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Harold and Susan Vordos wrote:
s "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip--- To the best of my knowledge, I chose the right service for my needs. Considering I have nothing that is wired for 208, nor can any of it be rewired to accommodate that voltage, I sure as hell didn't want it in the shop. If industry today is headed that direction, and machine tools are so wired, that's a whole different situation, and I'd have no quarrel with the choice. With the machines I have, that wasn't one of the options, and I sure as hell wasn't going to spring for transformers that weren't necessary, not when all I had to do is request the right service. It's likely that the potential issues diminish as the equipment gets newer. I certainly get that idea-----even PUD was somewhat surprised that I wanted the delta service. Stepping up for the one problem grinder makes sense, just as adding boost transformers makes sense if it's only a machine or two that need them. I don't agree on the boost transformers, not when I'm as pleased as I am to have the service I have. As I stated, I don't consider buying boost transformers to be a bargain, nor would I like feeding them on a continual basis, in spite of the fact that we pay only $.0445 kwh for our power. I have yet to discover one thing about my service that displeases me, and I've had 3 phase delta since 1967. One of us is nuts! :-) Remember, I'm not biased against delta service, I'm biased against wild leg delta service, two different things. You keep saying that, as if there's other types. I've heard of a corner grounded delta (but don't understand how it relates to voltage), but as far as I know, they all have a wild leg if you shoot for 120V. Is there something I don't know or understand? The moment you introduce the neutral, seems to me you're bound to have only two phases that yield 120V unless your wired wye. A pure delta service does not have a neutral at all. There is no 120v on it, only 240v phase to phase. The corner ground is strictly for safety purposes to limit the relative voltage from any phase to ground. This can make that phase look superficially like a neutral, but it is not. Were I planning a new shop with the full list of equipment to be in it, their specs, etc. I might well decide on a service configuration that included delta service for the machines. I would just avoid a service configuration that included a wild leg. OK---fill me in, then. What type of service would it be? Strictly 240 V? That's what I have now. I do *not* use my 3 phase for single phase service*, although when I wire my mill permanently, I will have single phase for the power feed and work light, but only there. I'll do that so I can keep the wires away from the bottom of the machine. I have the box overhead, almost directly over the motor on the mill. 12' ceiling. You can do that when you have a 5 wire system. Everything else is strictly 3 wires, plus ground. Do you still have heartburn over my wiring? *The same phases that constitute my A & C phases in the 3 phase panel feed my single phase panel, although through separate lines and conduit, from the pole. Want to see a pic? How are you going to wire the mill? Separate conduit from each panel to separate boxes overhead and separate drops to the mill head and the light / power feed? Is the neutral present in your three phase panel so you can do a single feed from there? You can't or at least shouldn't (I'd have to look in the code book) combine circuits fed from separate breakers in separate panels in a single conduit run to the mill. For the mill I would likely feed it strictly three phase and locally derive the 120v with a small transformer. Of course I got about a dozen 1 KVA 240/480 x 120/240 transformers for about $10 each brand new so that biases the economics a bit. Pete C. |
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On Tue, 14 Jun 2005 14:25:16 GMT, "Pete C."
wrote: Harold and Susan Vordos wrote: Chuckle! You, apparently, live in town. Not only could they not replace one for me in 15 minutes, it's highly unlikely they could do so in a couple hours. It would take no less than 45 minutes for someone to respond to our remote address, then the time it would take to get a transformer on location, assuming they had one in the yard. That case was indeed in town and it was a planned replacement. However, if you give them sufficient information when you log the trouble call I see no reason they couldn't have the correct transformer with them when they come out. Given the stock yards I've seen I think it's pretty unlikely that they would not have a suitable replacement on hand. So 15 min to replace + travel time to get there. So you're telling me they don't have a "hog wagon" or two parked at the local utility yard, all ready to grab and go? Around here they have several of them available in each area yard for most KVA sizes and voltages. (A trailer-mounted multi-tap transformer and a bunch of HV stranded motor-lead cable set up to come out of a hole on the top, or a big piece of liquidtight for armor to run into a pad-mount manhole. They just park it next to the dead transformer, set the taps to the supply and load voltages they need, run the cables down into the manhole or up to the top of the pole, and jumper around the dead transformer. Then you surround it with a jillion cones around the pole, or a portable fence to keep kiddies out of the manhole.) -- Bruce -- -- Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop Electrician for Westend Electric - CA726700 5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545 Spamtrapped address: Remove the python and the invalid, and use a net. |
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"Pete C." wrote in message ... Harold and Susan Vordos wrote: s "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip--- You keep saying that, as if there's other types. I've heard of a corner grounded delta (but don't understand how it relates to voltage), but as far as I know, they all have a wild leg if you shoot for 120V. Is there something I don't know or understand? The moment you introduce the neutral, seems to me you're bound to have only two phases that yield 120V unless your wired wye. (That should have said *you're*, not your. H) A pure delta service does not have a neutral at all. There is no 120v on it, only 240v phase to phase. The corner ground is strictly for safety purposes to limit the relative voltage from any phase to ground. This can make that phase look superficially like a neutral, but it is not. OK, that makes sense. From what you're saying, then, is that you don't object to delta so long as you don't derive any 120V from it aside from transforming. For all practical purposes, that's what I'm doing this time, using my delta service only for 3 phase, with all (except one place) of the 120V stuff coming from my single phase panel, which I would have done anyway, due to the demand meter. However, using the delta service for 120V is done routinely, as you likely know. The only real disadvantage I am aware of is the lost space in the panel---the B phase, the wild leg. Byond that, I don't see any issues. As far as I'm concerned, changing to 208 volts is a greater sacrifice than losing the few spaces, at least with the equipment I own. Were I planning a new shop with the full list of equipment to be in it, their specs, etc. I might well decide on a service configuration that included delta service for the machines. I would just avoid a service configuration that included a wild leg. OK---fill me in, then. What type of service would it be? Strictly 240 V? That's what I have now. I do *not* use my 3 phase for single phase service*, although when I wire my mill permanently, I will have single phase for the power feed and work light, but only there. I'll do that so I can keep the wires away from the bottom of the machine. I have the box overhead, almost directly over the motor on the mill. 12' ceiling. You can do that when you have a 5 wire system. Everything else is strictly 3 wires, plus ground. Do you still have heartburn over my wiring? How are you going to wire the mill? Separate conduit from each panel to separate boxes overhead and separate drops to the mill head and the light / power feed? Is the neutral present in your three phase panel so you can do a single feed from there? You can't or at least shouldn't (I'd have to look in the code book) combine circuits fed from separate breakers in separate panels in a single conduit run to the mill. As I said, my 3 phase service is 5 wire, meaning it is capable of delivering 120V single phase, per code. In the case of the mill, I'll take advantage of that and use the neutral, tapping either the A or C phase for the 120V. I have two boxes, side by side, coupled with a short nipple. One will have the three phase outlet for the mill, the other will have the single phase 120V, all fed from the same breaker, in the same conduit. It's clean and easy. Remember, we're dealing with only a few amps, tops. I'm not concerned about balancing the load in this case. For the mill I would likely feed it strictly three phase and locally derive the 120v with a small transformer. Of course I got about a dozen 1 KVA 240/480 x 120/240 transformers for about $10 each brand new so that biases the economics a bit. Chuckle! Put one of them in the mail to me and I'll wire it that way, so you won't worry about me and my safety! :-) Harold |
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Harold and Susan Vordos wrote:
"Pete C." wrote in message ... Harold and Susan Vordos wrote: s "Pete C." wrote in message ... Harold and Susan Vordos wrote: snip--- You keep saying that, as if there's other types. I've heard of a corner grounded delta (but don't understand how it relates to voltage), but as far as I know, they all have a wild leg if you shoot for 120V. Is there something I don't know or understand? The moment you introduce the neutral, seems to me you're bound to have only two phases that yield 120V unless your wired wye. (That should have said *you're*, not your. H) A pure delta service does not have a neutral at all. There is no 120v on it, only 240v phase to phase. The corner ground is strictly for safety purposes to limit the relative voltage from any phase to ground. This can make that phase look superficially like a neutral, but it is not. OK, that makes sense. From what you're saying, then, is that you don't object to delta so long as you don't derive any 120V from it aside from transforming. For all practical purposes, that's what I'm doing this time, using my delta service only for 3 phase, with all (except one place) of the 120V stuff coming from my single phase panel, which I would have done anyway, due to the demand meter. However, using the delta service for 120V is done routinely, as you likely know. The only real disadvantage I am aware of is the lost space in the panel---the B phase, the wild leg. Byond that, I don't see any issues. As far as I'm concerned, changing to 208 volts is a greater sacrifice than losing the few spaces, at least with the equipment I own. Were I planning a new shop with the full list of equipment to be in it, their specs, etc. I might well decide on a service configuration that included delta service for the machines. I would just avoid a service configuration that included a wild leg. OK---fill me in, then. What type of service would it be? Strictly 240 V? That's what I have now. I do *not* use my 3 phase for single phase service*, although when I wire my mill permanently, I will have single phase for the power feed and work light, but only there. I'll do that so I can keep the wires away from the bottom of the machine. I have the box overhead, almost directly over the motor on the mill. 12' ceiling. You can do that when you have a 5 wire system. Everything else is strictly 3 wires, plus ground. Do you still have heartburn over my wiring? How are you going to wire the mill? Separate conduit from each panel to separate boxes overhead and separate drops to the mill head and the light / power feed? Is the neutral present in your three phase panel so you can do a single feed from there? You can't or at least shouldn't (I'd have to look in the code book) combine circuits fed from separate breakers in separate panels in a single conduit run to the mill. As I said, my 3 phase service is 5 wire, meaning it is capable of delivering 120V single phase, per code. In the case of the mill, I'll take advantage of that and use the neutral, tapping either the A or C phase for the 120V. I have two boxes, side by side, coupled with a short nipple. One will have the three phase outlet for the mill, the other will have the single phase 120V, all fed from the same breaker, in the same conduit. It's clean and easy. Remember, we're dealing with only a few amps, tops. I'm not concerned about balancing the load in this case. For the mill I would likely feed it strictly three phase and locally derive the 120v with a small transformer. Of course I got about a dozen 1 KVA 240/480 x 120/240 transformers for about $10 each brand new so that biases the economics a bit. Chuckle! Put one of them in the mail to me and I'll wire it that way, so you won't worry about me and my safety! :-) Actually now that I think about it I believe they were marked at $10 and I got them for about $8 'cause I took the whole lot. I'm pretty sure the cost to ship one of those heavy little buggers across the country would far exceed what I paid for them although it would be much less than the $150 they seem to list for. Pete C. |
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"Bruce L. Bergman" wrote:
On Tue, 14 Jun 2005 14:25:16 GMT, "Pete C." wrote: Harold and Susan Vordos wrote: Chuckle! You, apparently, live in town. Not only could they not replace one for me in 15 minutes, it's highly unlikely they could do so in a couple hours. It would take no less than 45 minutes for someone to respond to our remote address, then the time it would take to get a transformer on location, assuming they had one in the yard. That case was indeed in town and it was a planned replacement. However, if you give them sufficient information when you log the trouble call I see no reason they couldn't have the correct transformer with them when they come out. Given the stock yards I've seen I think it's pretty unlikely that they would not have a suitable replacement on hand. So 15 min to replace + travel time to get there. So you're telling me they don't have a "hog wagon" or two parked at the local utility yard, all ready to grab and go? Around here they have several of them available in each area yard for most KVA sizes and voltages. (A trailer-mounted multi-tap transformer and a bunch of HV stranded motor-lead cable set up to come out of a hole on the top, or a big piece of liquidtight for armor to run into a pad-mount manhole. They just park it next to the dead transformer, set the taps to the supply and load voltages they need, run the cables down into the manhole or up to the top of the pole, and jumper around the dead transformer. Then you surround it with a jillion cones around the pole, or a portable fence to keep kiddies out of the manhole.) I've seen plenty of those trailer setups as well, some rather large and "polished" looking with cooling fans and everything. The scariest temp setup I ever saw was in Philly. I'm walking down a nice tree lined street and see a few cones and a plywood box wall around a spot along side the sidewalk. Getting closer I see that there is a short run of the Yellow-jacket cable guard running between the plywood wall and the nearest tree. When I got up to it and looked over the 4' high plywood wall I saw a half excavated manhole with three HV "elbow" connectors feeding three HV lines that went through the Yellow-jacket and then exposed up the side of the tree. The lines continued along from tree to tree, perhaps 8' up, tied in place with pieces of yellow poly rope for what had to be at least 400' down the street before they crossed over the street and continued down and alley as far as I could see, tied off to fire escapes and whatever else was handy. I don't recall a single high voltage warning sign anywhere. I wish I had a camera with me. Pete C. |
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"Pete C." wrote:
A pure delta service does not have a neutral at all. There is no 120v on it, only 240v phase to phase. The corner ground is strictly for safety purposes to limit the relative voltage from any phase to ground. This can make that phase look superficially like a neutral, but it is not. Wrong. If it is a grounded (not grounding) circuit conductor, it IS a neutral, by definition. jk |
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