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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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#1
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
Bruce (or anyone qualified).....
Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. |
#2
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Pinging Bruce for Clarification
On Fri, 07 Sep 2007 02:10:27 GMT, Ken Sterling (Ken Sterling) Ken wrote:
Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? yes Single phase power - 220v - isn't each leg 180 degrees from the other? Single phase means there is one leg only. Think of single phase as line segment (one line) and three phase as a triangle (three lines). If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, Each leg is single phase. it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Read wikipedia article on Three Phase Power, it is very good. i |
#3
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
Ken Sterling wrote:
Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. Three phase is usually 208/120. 208 volts between phases and 120 volts leg to ground. Many machines have a 200 volt tap for this situation. Stuart |
#4
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
Ken Sterling (Ken Sterling) wrote in message ... Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. If your three phase power is 220/230/240 volts phase-to-phase, which is common, you get normal 220/230/240 volts single phase between any two phases. So your machine will not only work, it will be connected to its proper power. This topic generally starts a really long and involved thread, so stand by. There is quite a bit more that can be learned about the voltages, currents, and phase angles and there is some disagreement about the terminology involved. Don Young |
#5
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
You question is really "can I run a 3 phase motor on single phase?"
Answer is a qualified maybe: since you will be running only 2 of the 3 phases, you can only get 2/3rds of the rated power. Plus you will need to run some capacitors to pick up the 3rd leg to get it to start in the desired direction. This is the approach used by a static phase converter. Real answer is to run a rotary phase converter or a VFD. Ken Sterling wrote: Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. |
#6
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
RoyJ wrote:
You question is really "can I run a 3 phase motor on single phase?" Answer is a qualified maybe: since you will be running only 2 of the 3 phases, you can only get 2/3rds of the rated power. Plus you will need to run some capacitors to pick up the 3rd leg to get it to start in the desired direction. This is the approach used by a static phase converter. Real answer is to run a rotary phase converter or a VFD. No his question was the reverese, "can I run a single phase load from a 3 phase source" THe answer of course being yes. Ken Sterling wrote: Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. jk |
#7
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
RoyJ wrote:
You question is really "can I run a 3 phase motor on single phase?" Answer is a qualified maybe: since you will be running only 2 of the 3 phases, you can only get 2/3rds of the rated power. Plus you will need to run some capacitors to pick up the 3rd leg to get it to start in the desired direction. This is the approach used by a static phase converter. Real answer is to run a rotary phase converter or a VFD. Re-read his question please, it's the exact opposite of what you indicate. The short answer is that yes, a 220V single phase machine will generally run just fine on power from a three phase service. In some rare cases the fact that the typical three phase supply in a commercial environment is 208/120V wye service and therefore only provides 208V phase to phase can be an issue and the machine may have a transformer with adjustable taps to account for that, or you can use buck/boost transformers to compensate. In industrial environments you may have 220V three phase delta service where you actually get 220V phase to phase and there isn't a voltage issue. The 120 degree phase angle has no practical effect generally. Ken Sterling wrote: Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. |
#8
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
On Fri, 07 Sep 2007 02:10:27 GMT, Ken Sterling (Ken Sterling) wrote:
Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Right. Figuring the sine wave overlap, it's more like six-phase power - every 60 degrees of an electric motor rotation one of the phases is at peak voltage, either negative or positive. That's why it's so darned efficient for running motors, since there's always smooth forward motion. It's the difference betweeen a one-lung hit and miss Johnny Popper and a Packard Merlin. And vibration sensitive things like surface grinders should only run on real 3-phase, for the same reason. Try running it on a phase converter and the surface finish on the products can go straight to heck. Single phase power - 220v - isn't each leg 180 degrees from the other? Residential style 120/240 single phase is one center-tapped transformer winding, with the center tap grounded for the Neutral. The '180 degrees' is a convenient way to explain it because the polarity /appears/ to be opposite when viewed/measured from the center tap. In reality there's no differential at all. If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Absolutely - you are going across one secondary core winding of the utility distribution transformer, and there's no worry about phase angle there. Two times to worry: One is if you have 120/208V Wye power, because it is only 208V phase to phase. Most small motors are dual-voltage rated 208V/240V and will gladly run on 208V but at a higher current draw. But there ARE pieces of gear that do not take kindly to running on 208V - this is when you connect a simple 16V/32V Buck-Boost transformer between the utility and the load to kick 208V up to 240V. The other: If you have 120/240 Open Delta or "High Leg" power - the High Leg (usually coded Orange and connected as B phase, but not always) is 208V to ground, not 120V. When you run across Open Delta panels in the field, it is considerate to put a big note on the breaker panel to warn the less enlightened among us that 'The B Phase is 208V to ground, and connecting 120V loads to the B Phase is a Very Bad Idea.' You can connect 240V loads between any two phases on Open Delta, but you can only connect 120V light loads between A-N and C-N. Try placing them on B-N and they won't live very long - but they glow really bright before they blow... -- Bruce -- |
#9
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
On Thu, 06 Sep 2007 22:34:44 -0400, Stuart Wheaton
wrote: Three phase is usually 208/120. 208 volts between phases and 120 volts leg to ground. Many machines have a 200 volt tap for this situation. Or 277V/480V. 277 between Phase to Neutral, and 480V Phase-Phase. Found in larger high-rise buildings, large shopping malls, and light industrial, because the higher voltage means much smaller wiring for the same work produced. When you get close to the end-use location for 120V/208V/240V power you place a step-down transformer. That keeps the voltage drop to a minimum. Heavy industry (automobile plants, steel mills, forges, foundries, mines, etc.) buys their power "in bulk" at the higher utility distribution voltages in use in their area - 2,400V (almost extinct) 4,800V (LADWP Residential) 9,600V 14,500V 34,500V (LADWP Industrial) etc... The utility installs fuses or breakers and a KWH Meter recording the power usage on the line going into the complex, and the end user takes over. The industrial user gets the power cheaper, but has to supply their own underground or aerial cabling, step-down transformers and switchgear, and knock the medium voltage down to the needed voltage at the point of use. And they have to absorb the cost of all the transformer and transmission losses that occur after they 'buy' the power at the KWH Meter. -- Bruce -- |
#10
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
On Thu, 06 Sep 2007 22:34:44 -0400, Stuart Wheaton
wrote: Ken Sterling wrote: Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. Three phase is usually 208/120. 208 volts between phases and 120 volts leg to ground. Many machines have a 200 volt tap for this situation. Stuart Its usually 240/120. Do the math Gunner |
#11
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
On Thu, 06 Sep 2007 23:07:32 -0700, Bruce L. Bergman
wrote: Two times to worry: One is if you have 120/208V Wye power, because it is only 208V phase to phase. Most small motors are dual-voltage rated 208V/240V and will gladly run on 208V but at a higher current draw. But there ARE pieces of gear that do not take kindly to running on 208V - this is when you connect a simple 16V/32V Buck-Boost transformer between the utility and the load to kick 208V up to 240V. The other: If you have 120/240 Open Delta or "High Leg" power - the High Leg (usually coded Orange and connected as B phase, but not always) is 208V to ground, not 120V. When you run across Open Delta panels in the field, it is considerate to put a big note on the breaker panel to warn the less enlightened among us that 'The B Phase is 208V to ground, and connecting 120V loads to the B Phase is a Very Bad Idea.' You can connect 240V loads between any two phases on Open Delta, but you can only connect 120V light loads between A-N and C-N. Try placing them on B-N and they won't live very long - but they glow really bright before they blow... Indeed. Even if they dont have a light source..they can glow really nicely. Then the magic smoke comes out. -- Bruce -- Gunner, who has been putting orange tape on all manner of things the last few months...... Orange County is nearly all Open Delta and 240 vts |
#12
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
"RoyJ" wrote ...
You question is really "can I run a 3 phase motor on single phase?" Ken Sterling wrote: If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you I think his question was the other way around. |
#13
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
Three phase power ----- isn't each leg 120 degrees from the others?
yes Single phase power - 220v - isn't each leg 180 degrees from the other? Single phase means there is one leg only. Think of single phase as line segment (one line) and three phase as a triangle (three lines). A lot of the confusion in power phases is that you need to look at where you are measuring the voltages and where the ground is. If you are just connecting the two hot leads of the 240 line into your house, you have one 240 volt phase. If you also connect the ground, you have two 120 volt phases that are 180 degrees apart. Three phase power has the three phases 120 degrees apart but the voltages and ground can be referenced different ways. You can also refer to them in different ways, depending on how you are using the power. The common ones are Y with the voltage measured between each phase and the ground centered between the phases and Delta where the voltage is measured between the ends of the phases. 208/120 (Y) is common for large buildings because it gives three 120 volt phases using the ground to each phase. If you connect directly between two phases (withoug connecting to the ground) you have a single phase 208 volt connection. A third option is to connect all three phases (but not the ground) and have a 208 three phase delta power. 240 Delta with a ground at the mid point of one phase is common in small industrial buildings. It gives the 240 three phase power that many machines want , allows you to connect single phase 240 equipment (if it doesn't need a ground) to any of the phases, connect single phase 240 equipment (if it needs a ground) to the phase with the ground, and two 120 phases on the grounded phase. If the available three phase power is the common 240 V delta with the ground in a leg, your 240V single phase machine is absolutely going to work when connected to the leg with the ground. If the machine does not need the ground as reference, it can work on any 240 volt phase. If you have 208/120 Y three phase power and the machine is not rated to run on 240/208, then it becomes messier. If you don't need a ground, you can run a 208-240 boost transformer (autotransformer that just makes up the difference between the 208 and 240) to run it. If you need a mid phase ground, you could run a 208-240 center tapped transformer. You connect the input to a 208 phase and the output's center tap to the ground. Isn't this "fun". |
#14
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
Gunner wrote:
On Thu, 06 Sep 2007 22:34:44 -0400, Stuart Wheaton wrote: Ken Sterling wrote: Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. Three phase is usually 208/120. 208 volts between phases and 120 volts leg to ground. Many machines have a 200 volt tap for this situation. Stuart Its usually 240/120. Do the math Gunner 240 for delta service, but you're more likely to find 208/120 wye service in most places. |
#15
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
On Fri, 07 Sep 2007 08:40:40 -0500, "Pete C."
wrote: Gunner wrote: On Thu, 06 Sep 2007 22:34:44 -0400, Stuart Wheaton wrote: Ken Sterling wrote: Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. Three phase is usually 208/120. 208 volts between phases and 120 volts leg to ground. Many machines have a 200 volt tap for this situation. Stuart Its usually 240/120. Do the math Gunner 240 for delta service, but you're more likely to find 208/120 wye service in most places. Not in Southern California, if my 10+ yrs of machine tool repair is any indicator. Gunner |
#16
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
Gunner wrote:
On Fri, 07 Sep 2007 08:40:40 -0500, "Pete C." wrote: Gunner wrote: On Thu, 06 Sep 2007 22:34:44 -0400, Stuart Wheaton wrote: Ken Sterling wrote: Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. Three phase is usually 208/120. 208 volts between phases and 120 volts leg to ground. Many machines have a 200 volt tap for this situation. Stuart Its usually 240/120. Do the math Gunner 240 for delta service, but you're more likely to find 208/120 wye service in most places. Not in Southern California, if my 10+ yrs of machine tool repair is any indicator. Gunner All of the commercial / light industrial places I've been to had 208/120 Y service. Only seen 240 delta in heavy industrial settings. Based on some 5 yrs of CNC service in the northeast. |
#17
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
On Fri, 07 Sep 2007 02:10:27 GMT, Ken Sterling (Ken Sterling) wrote:
Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. It may help to think of a "phase" as a pair of conductors rather than a wire. A pair of wires comprises a phase. With threephase, there are three wires, call them A, B, and C. (Ignoring ground for the moment). There are therefore three phases: AB, AC and BC. The sinusoidal voltages on these phases are 120 degrees apart. The voltages on each of these wires relative to ground will also be 120 degrees apart but line-to-ground voltage in a wye connection is .867 * line-to-line voltage. Residential single phase power in the US is 120 volts relative to ground, or 240 volts line-to-line because one line has polarity opposite (180 deg phase shift) to the other w.r.t. ground. Household 120 volt power has one or the other of these lines on the black wire, and neutral (grounded somewhere) on the white wire. 240 volt loads like stoves are connected line-to-line, often do not use the neutral. Others have treated the various voltages found on each phase of commonly-found three-phase power distribution setups. |
#18
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Pinging Bruce for Clarification
Ken Sterling wrote: Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. Ken To visualize phase angles draw 3 parallel lines the same length, put a dot at the left end of the top line, and a dot at the right end of the middle line, and a dot in the middle of the last line. Now imagine those dots moving at the same time, the same speed from one end to the other. Their timing is 120 deg apart and if you look only at the top and middle lines, they are 180 deg apart. 120/208 is star or y just imagine each leg of the y is a coil of a transformer and the middle of the y is grounded. Each end of the y is a phase, the voltage is phase to ground 120, phase to phase 208. On a 120/208 bank all 3 transformers will be the same size. 120/240 is delta imagine a triangle, each side is a coil of a transformer, each point is a phase, in the middle of one side draw a ground. The transformer you ground is the lighting transformer. It has all the single phase load. The voltage is hot leg to ground 120, hot leg to ground 120, power,high,or stinger leg to ground 208, because it is a coil and a half away from ground. Between any 3 hot is 240v. In a 120/240 bank the middle or lighting transformer will be larger to handle the 3phase plus the single phase load. To visualize an open delta erase one side of the triangle. The only way you can tell if you have an open delta versus a delta is to look at the bank, 2 transformers is open delta, 3 is delta. Open delta is not very efficient. It is good for temporary repairs. I could rebuss a bank to open delta so a farmer could milk his cows and not have to wait 4hr for a crew to change out 1 transformer. The secondary coil of the transformers is not center tapped. It is two coils, you have them serialed for 240 and paralleled for 208. You can see some pages from a transformer manual at http://murrayranch.com/Electricity.htm Don |
#19
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Pinging Bruce for Clarification
Gunner wrote:
On Thu, 06 Sep 2007 22:34:44 -0400, Stuart Wheaton wrote: Ken Sterling wrote: Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. Three phase is usually 208/120. 208 volts between phases and 120 volts leg to ground. Many machines have a 200 volt tap for this situation. Stuart Its usually 240/120. Do the math 120 * SqrRoot 3 (1.73)= 208 Hmmm I did the math, then I stuck the probes of my Fluke on the 3 phase into our shop, and almost every other large distro I've ever had to work in and found 208/120. If your little corner of the world is different, it ain't my fault. But then again, so much of your little world doesn't agree with reality, why should this be different. Stuart |
#20
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Pinging Bruce for Clarification
Mastic wrote:
All of the commercial / light industrial places I've been to had 208/120 Y service. Only seen 240 delta in heavy industrial settings. Based on some 5 yrs of CNC service in the northeast. I have 440 delta and 240 single phase in my garage, delivered from the mains. Lucky you. Not much need for 440 and the more expensive switchgear to go with it unless you have a really big installation. |
#21
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Pinging Bruce for Clarification
On Sat, 08 Sep 2007 09:12:18 -0500, "Pete C." wrote:
Mastic wrote: All of the commercial / light industrial places I've been to had 208/120 Y service. Only seen 240 delta in heavy industrial settings. Based on some 5 yrs of CNC service in the northeast. I have 440 delta and 240 single phase in my garage, delivered from the mains. Lucky you. Not much need for 440 and the more expensive switchgear to go with it unless you have a really big installation. Or you have a small shop operation and need to run specialized gear that only comes 480V 3-Ph. You can do a LOT more from a 480V 200A service than from a 240V 200A service. You can boost 240V up to 480V with transformers, but you have to be careful to not max out the 240V service. The front office gets very annoyed when you blow the main and black out the whole building. -- Bruce -- |
#22
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Pinging Bruce for Clarification
"Bruce L. Bergman" wrote:
On Sat, 08 Sep 2007 09:12:18 -0500, "Pete C." wrote: Mastic wrote: All of the commercial / light industrial places I've been to had 208/120 Y service. Only seen 240 delta in heavy industrial settings. Based on some 5 yrs of CNC service in the northeast. I have 440 delta and 240 single phase in my garage, delivered from the mains. Lucky you. Not much need for 440 and the more expensive switchgear to go with it unless you have a really big installation. Or you have a small shop operation and need to run specialized gear that only comes 480V 3-Ph. You can do a LOT more from a 480V 200A service than from a 240V 200A service. You can boost 240V up to 480V with transformers, but you have to be careful to not max out the 240V service. The front office gets very annoyed when you blow the main and black out the whole building. -- Bruce -- If it's even remotely close to maxing out a 240V 200A 3ph service, it's a big installation, no mater how physically small it may be. |
#23
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Pinging Bruce for Clarification
On Fri, 07 Sep 2007 16:20:57 GMT, "Pete C."
wrote: 240 for delta service, but you're more likely to find 208/120 wye service in most places. Not in Southern California, if my 10+ yrs of machine tool repair is any indicator. Gunner All of the commercial / light industrial places I've been to had 208/120 Y service. Only seen 240 delta in heavy industrial settings. Based on some 5 yrs of CNC service in the northeast. Probably a regional thing. Shrug Gunner |
#24
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Pinging Bruce for Clarification
On Sun, 09 Sep 2007 03:13:48 GMT, "Pete C."
wrote: "Bruce L. Bergman" wrote: On Sat, 08 Sep 2007 09:12:18 -0500, "Pete C." wrote: Mastic wrote: All of the commercial / light industrial places I've been to had 208/120 Y service. Only seen 240 delta in heavy industrial settings. Based on some 5 yrs of CNC service in the northeast. I have 440 delta and 240 single phase in my garage, delivered from the mains. Lucky you. Not much need for 440 and the more expensive switchgear to go with it unless you have a really big installation. Or you have a small shop operation and need to run specialized gear that only comes 480V 3-Ph. You can do a LOT more from a 480V 200A service than from a 240V 200A service. You can boost 240V up to 480V with transformers, but you have to be careful to not max out the 240V service. The front office gets very annoyed when you blow the main and black out the whole building. -- Bruce -- If it's even remotely close to maxing out a 240V 200A 3ph service, it's a big installation, no mater how physically small it may be. Chuckle..I did that yesterday. Had 6 Moog Hydrapoints and 4 Okuma Twin Turrets running on a 200 amp. Then I added a Okuma LS2200 Ooops Well..he was hogging with a 1.25" drill bit. Shrug The hogging exceeded my very very thin margin.. Busted tools in just about every machine. Gunner |
#25
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Pinging Bruce for Clarification
On Fri, 07 Sep 2007 17:46:59 -0400, Stuart Wheaton
wrote: Gunner wrote: On Thu, 06 Sep 2007 22:34:44 -0400, Stuart Wheaton wrote: Ken Sterling wrote: Bruce (or anyone qualified)..... Three phase power ----- isn't each leg 120 degrees from the others? Single phase power - 220v - isn't each leg 180 degrees from the other? If the above is correct (and I'm hoping I understand it correctly) it would stand to reason, that if you needed to hook up a 220v single phase machine and you had 3 phase available at that location you could, (and I am not saying it's correct) connect to two of the three phases and run the machine, even tho the sine waves wouldn't be 180 out, it probably wouldn't hurt anything. Am I correct in this assumption??? Any and all comments welcome Thanks. Ken. Three phase is usually 208/120. 208 volts between phases and 120 volts leg to ground. Many machines have a 200 volt tap for this situation. Stuart Its usually 240/120. Do the math 120 * SqrRoot 3 (1.73)= 208 Hmmm I did the math, then I stuck the probes of my Fluke on the 3 phase into our shop, and almost every other large distro I've ever had to work in and found 208/120. If your little corner of the world is different, it ain't my fault. But then again, so much of your little world doesn't agree with reality, why should this be different. Stuart Well...shrug..it is California. The 7th largest economy in the world. You did say you live in the Rust Belt, right? Gunner |
#26
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Pinging Bruce for Clarification
Mastic wrote:
"Pete C." wrote: Mastic wrote: All of the commercial / light industrial places I've been to had 208/120 Y service. Only seen 240 delta in heavy industrial settings. Based on some 5 yrs of CNC service in the northeast. I have 440 delta and 240 single phase in my garage, delivered from the mains. Lucky you. Not much need for 440 and the more expensive switchgear to go with it unless you have a really big installation. I just have a Bridgeport mill clone and a lathe in my garage, pure hobby stuff. The machines have built in 440 volt switchgear. David That isn't switchgear, it's machine controls. The switchgear is the meter socket and distribution panel for the 440V delta service, both of which cost significantly more than the equivelents for 220V delta service, which those machines will happily run on. I'd never consider 440V service until I had at least 6 large CNC machines. |
#27
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Pinging Bruce for Clarification
On Sat, 08 Sep 2007 23:28:10 -0700, Gunner
wrote: On Sun, 09 Sep 2007 03:13:48 GMT, "Pete C." wrote: If it's even remotely close to maxing out a 240V 200A 3ph service, it's a big installation, no mater how physically small it may be. Chuckle..I did that yesterday. Had 6 Moog Hydrapoints and 4 Okuma Twin Turrets running on a 200 amp. Then I added a Okuma LS2200. Ooops Well..he was hogging with a 1.25" drill bit. Shrug The hogging exceeded my very very thin margin.. No, more like you were betting on not all the machines running at the same time, let alone several of them running flat out and hogging at the same moment... And as you can see, that isn't a smart bet. Busted tools in just about every machine. And the front office people probably weren't amused when their computers and AC went away either. Is this an industrial park, or can they bump the service up? How many of those machines are dual 240/480V? You can get the new service in and change them over one at a time. Sometimes you can cheat - if this is in an industrial park and the unit next door is only being used as a warehouse, they aren't using their full 200A service - you can install a sub-meter and get some more electricity from them. -- Bruce -- |
#28
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Pinging Bruce for Clarification
On Sun, 09 Sep 2007 13:39:03 -0700, Bruce L. Bergman
wrote: On Sat, 08 Sep 2007 23:28:10 -0700, Gunner wrote: On Sun, 09 Sep 2007 03:13:48 GMT, "Pete C." wrote: If it's even remotely close to maxing out a 240V 200A 3ph service, it's a big installation, no mater how physically small it may be. Chuckle..I did that yesterday. Had 6 Moog Hydrapoints and 4 Okuma Twin Turrets running on a 200 amp. Then I added a Okuma LS2200. Ooops Well..he was hogging with a 1.25" drill bit. Shrug The hogging exceeded my very very thin margin.. No, more like you were betting on not all the machines running at the same time, let alone several of them running flat out and hogging at the same moment... And as you can see, that isn't a smart bet. The customer was betting on it. I warned him many months ago. On the other hand..he pays very well and on time. Shrug. Busted tools in just about every machine. And the front office people probably weren't amused when their computers and AC went away either. Is this an industrial park, or can they bump the service up? I bumped it up from 200 amps total to 800 amps total, with multiple services. 4 shops in the complex, one with 600 amps total, 1 with 200 amps on the same meter main, and 2 with seperate 200 amp meter mains. It took 3 months for the City and So Cal Edison to get their heads out of their asses on the new meter main..with another 2 weeks to convince the city inspector that 1992 Okumas never had, nor never will have UL listings. How many of those machines are dual 240/480V? You can get the new service in and change them over one at a time. Nope..only about 25% are dual voltage. Sometimes you can cheat - if this is in an industrial park and the unit next door is only being used as a warehouse, they aren't using their full 200A service - you can install a sub-meter and get some more electricity from them. -- Bruce -- Already doing that with the 120 volt service...the bulding was built in 1959. Most of the shops had single 50 amp 120 volt service with a meter attached to the 6 breaker "main" They hired an engineering company at the outset. Then they expected me to impliment the results. Ive many compliments on the quality of workmanship, the way I designed everything for future expansion and so forth. I dont get any brownie points for not getting 400 amps from a 200 amp service. Shrug Its safe, its up to code, it looks good. But they simply dont have enough power in some places. And it will take an act of Crom to get anyone to make it so. Then they stuck (2) I-R 15hp screw compressors and the dryers into the mix...cringe. Gunner |
#29
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Pinging Bruce for Clarification
On Mon, 10 Sep 2007 02:31:36 -0700, Gunner wrote:
On Sun, 09 Sep 2007 13:39:03 -0700, Bruce L. Bergman wrote: I bumped it up from 200 amps total to 800 amps total, with multiple services. 4 shops in the complex, one with 600 amps total, 1 with 200 amps on the same meter main, and 2 with seperate 200 amp meter mains. It took 3 months for the City and So Cal Edison to get their heads out of their asses on the new meter main..with another 2 weeks to convince the city inspector that 1992 Okumas never had, nor never will have UL listings. How many of those machines are dual 240/480V? You can get the new service in and change them over one at a time. Nope..only about 25% are dual voltage. Darn. Well, if you can get both flavors of power from Edison you can change over the ones that can take 480V, and that takes a lot of pressure off the 240V service. Will help the compressor problem. Sometimes you can cheat - if this is in an industrial park and the unit next door is only being used as a warehouse, they aren't using their full 200A service - you can install a sub-meter and get some more electricity from them. Already doing that with the 120 volt service...the bulding was built in 1959. Most of the shops had single 50 amp 120 volt service with a meter attached to the 6 breaker "main" Were they still on A-Base meters and fuses? ;-) They hired an engineering company at the outset. Then they expected me to impliment the results. Ive many compliments on the quality of workmanship, the way I designed everything for future expansion and so forth. I dont get any brownie points for not getting 400 amps from a 200 amp service. Shrug Hey, one place was trying to suck 200A through a 100A meter socket and Type RHW risers. They thought upgrading the panel to a 200A would solve everything... The rubber insulation was a bit crispy crackly after 50 years in that pipe. Its safe, its up to code, it looks good. But they simply dont have enough power in some places. And it will take an act of Crom to get anyone to make it so. Been there... Remember when houses had a 30A service because "we'd never need anything more than that..."? Then the single-family house standard went to the 70A "Crowfoot" panel. Then 100A. Then 125A. We held at 200 for a while, and now they skipped straight to 400A... Progress marches on, and there's always another wonderful labor-saving (and power sucking) tool or appliance right around the corner. Then they stuck (2) I-R 15hp screw compressors and the dryers into the mix...cringe. Hey, that helps the power situation if they are put in constant-run mode and cycle on the unloaders, then there's only one start surge per shift. And it's those essentially locked-rotor start surges that kick the demand factor through the roof, and trip that Main Breaker that's teetering on the edge. -- Bruce -- |
#30
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Pinging Bruce for Clarification
On Mon, 10 Sep 2007 09:11:36 -0700, Bruce L Bergman wrote:
Hey, that helps the power situation if they are put in constant-run mode and cycle on the unloaders, then there's only one start surge per shift. And it's those essentially locked-rotor start surges that kick the demand factor through the roof, and trip that Main Breaker that's teetering on the edge. An electronic soft start drive (or a VFD) could help here, right? i |
#31
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
On Mon, 10 Sep 2007 11:21:13 -0500, Ignoramus2883
wrote: On Mon, 10 Sep 2007 09:11:36 -0700, Bruce L Bergman wrote: Hey, that helps the power situation if they are put in constant-run mode and cycle on the unloaders, then there's only one start surge per shift. And it's those essentially locked-rotor start surges that kick the demand factor through the roof, and trip that Main Breaker that's teetering on the edge. An electronic soft start drive (or a VFD) could help here, right? i When you start a motor from a dead stop it draws the full rated locked rotor current for a few hundred milliseconds till it gets started rotating, and then the current ramps down over the next three to five seconds as the motor gets itself and the load moving and up to speed. When you pay for commercial power with a demand factor, there's a demand meter that records the highest peak momentary amperage you draw. Looks like a big speedometer dial on the meter face, that's what they use the reset arm in the middle of the glass for... And they add a multiplication factor to your overall KWH billing rates based on the peak current you have drawn - this is to compensate the utility for supplying the oversized transformers needed to accommodate those current spikes, the transformers still draw current to energize the windings even if you only draw loads for a short period per day. A motor drive can only help so much - it can regulate the LRA current to an extent, but it still takes a big grunt to get the load spinning. And the heating problem is still there. Soft Starts are practical for motors that are expected to have short starts, like elevator pumps - but it's just as effective and less money to use a "Delta-Wye" reduced voltage starter on those motors. They get the motor spinning on Wye 277V and switch to Delta 480V running when up to roughly 80% speed. Short cycling kills motors fast because they don't run long enough to cool off from the start surge heating, then they stop and the air cooling stops, then they are asked to start again with the windings still hot. Do that a few times, and the Magic Smoke (TM) escapes. The trick on a constant-run compressor is there's only one start surge when you turn it on at the beginning of the day, usually with nothing else running. After that the compressor just opens the valves and spins idle, and the current draw drops off. (Not to zero, but the lack of start surges makes up for it.) |
#32
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
On Mon, 10 Sep 2007 13:38:58 -0700, Bruce L Bergman wrote:
On Mon, 10 Sep 2007 11:21:13 -0500, Ignoramus2883 wrote: On Mon, 10 Sep 2007 09:11:36 -0700, Bruce L Bergman wrote: Hey, that helps the power situation if they are put in constant-run mode and cycle on the unloaders, then there's only one start surge per shift. And it's those essentially locked-rotor start surges that kick the demand factor through the roof, and trip that Main Breaker that's teetering on the edge. An electronic soft start drive (or a VFD) could help here, right? i When you start a motor from a dead stop it draws the full rated locked rotor current for a few hundred milliseconds till it gets started rotating, and then the current ramps down over the next three to five seconds as the motor gets itself and the load moving and up to speed. When you pay for commercial power with a demand factor, there's a demand meter that records the highest peak momentary amperage you draw. Looks like a big speedometer dial on the meter face, that's what they use the reset arm in the middle of the glass for... And they add a multiplication factor to your overall KWH billing rates based on the peak current you have drawn - this is to compensate the utility for supplying the oversized transformers needed to accommodate those current spikes, the transformers still draw current to energize the windings even if you only draw loads for a short period per day. A motor drive can only help so much - it can regulate the LRA current to an extent, but it still takes a big grunt to get the load spinning. And the heating problem is still there. Soft Starts are practical for motors that are expected to have short starts, like elevator pumps - but it's just as effective and less money to use a "Delta-Wye" reduced voltage starter on those motors. They get the motor spinning on Wye 277V and switch to Delta 480V running when up to roughly 80% speed. Short cycling kills motors fast because they don't run long enough to cool off from the start surge heating, then they stop and the air cooling stops, then they are asked to start again with the windings still hot. Do that a few times, and the Magic Smoke (TM) escapes. The trick on a constant-run compressor is there's only one start surge when you turn it on at the beginning of the day, usually with nothing else running. After that the compressor just opens the valves and spins idle, and the current draw drops off. (Not to zero, but the lack of start surges makes up for it.) Bruce, forgive my ignorance, but let's say that a compressor has an unloader valve (even better, electrically controlled). Then the motor can be slowly ramped up to speed using a electronic drive, with the unloader engaging at the proper moment, right? My compressor is single phase, but my Bridgeport is 3 phase, on a VFD, set to accelerate over 1 second when turned on. I am sure that it does not draw anywhere close to the LRA when accelerating that slowly. What am I missing? i |
#33
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
After a Computer crash and the demise of civilization, it was learned
Gunner wrote on Mon, 10 Sep 2007 02:31:36 -0700 in rec.crafts.metalworking : Well..he was hogging with a 1.25" drill bit. Shrug The hogging exceeded my very very thin margin.. No, more like you were betting on not all the machines running at the same time, let alone several of them running flat out and hogging at the same moment... And as you can see, that isn't a smart bet. The customer was betting on it. I warned him many months ago. On the other hand..he pays very well and on time. Shrug. Sounds like he'll get to do it some more. Pay well, and on time. Good to have customers like that. pyotr -- pyotr filipivich "Quemadmoeum gladuis neminem occidit, occidentis telum est. " Lucius Annaeus Seneca, circa 45 AD (A sword is never a killer, it is a tool in the killer's hands.) |
#34
Posted to rec.crafts.metalworking
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Pinging Bruce for Clarification
Sorry everyone....
for some unknown reason... I didn't get the original post or the original responses. I know they made it through, cause I saw them on the Google newsgroups at work (but I'm not set up to post there). I didn't get them at home, but I did get the posts under the header Wondering how I can get Google to "send" the original headers and posts to my home computer.... any help here??? Thanks. Ken. Mastic wrote: All of the commercial / light industrial places I've been to had 208/120 Y service. Only seen 240 delta in heavy industrial settings. Based on some 5 yrs of CNC service in the northeast. I have 440 delta and 240 single phase in my garage, delivered from the mains. Lucky you. Not much need for 440 and the more expensive switchgear to go with it unless you have a really big installation. |
#35
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Pinging Bruce for Clarification
On Mon, 10 Sep 2007 15:44:11 -0500, Ignoramus2883
wrote: Bruce, forgive my ignorance, but let's say that a compressor has an unloader valve (even better, electrically controlled). Then the motor can be slowly ramped up to speed using a electronic drive, with the unloader engaging at the proper moment, right? If it has a centrifugal unloader that will not start pumping till the compressor comes up to full speed and the oil pressure comes up, like the higher end units from I-R and Quincy, yes the motor is essentially starting unloaded - well, except for getting the rotating mass of the motor and compressor moving. You will still see a current spike at start, but not as big and it will ramp down faster because the motor isn't trying to produce work before getting up to speed. And for that, a start controller or VFD would be even easier on the motor and your power bill. My compressor is single phase, but my Bridgeport is 3 phase, on a VFD, set to accelerate over 1 second when turned on. I am sure that it does not draw anywhere close to the LRA when accelerating that slowly. What am I missing? That your Bridgeport is manually started when you are standing right there, and if something goes seriously wrong you can kill the power. Most compressors are designed to a price point (keep the mfg. costs as cheap as practical while meeting the specs for capacity and durability) so they won't spend for a soft-start. Unloaders cost more, so they are only built into the higher end units. And the compressor is expected to run unattended and start itself reliably every time air is called for, for decades, without anyone needing to run up and slap the power switch off if it stalls. So the K.I.S.S. Principle says leave the electronics out if you don't really need them. A VFD will work if you just set it at 60.0 Hz, but the whole idea behind it is Variable Frequency. The only reason I'd install one on a compressor is if you want to play around with Logic Controllers and adjusting the motor speed to the air consumption. You can install one if you have one laying around and you want to (Play) experiment. But I still stand by "If it ain't broke..." -- Bruce -- |
#36
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Pinging Bruce for Clarification
To send the replies to your home computer, you could copy & paste the
contents of the replies to a text document, while viewing the Google RCM group on any machine, then save the text file and attach it to an email, then send it to your email address and access it from home. I just looked at some Goog RCM messages, and they have a Forward link at the bottom of each message, but it only works if you're signed in as a registered Goog member/subscriber. This is yet another reason to have a couple of unimportant free Yahoo email addresses. Then you can join/subscribe to something useless like Goog Groups with a Yahoo email address as your username, and not have your ISP email address used at numerous places, attracting spam and nasties. Then, with a Goog username, you can forward those Goog Group RCM messages/replies from Goog Groups to your Yahoo email account (which you can access from anywhere), or to your other email account. There are lots of worthwhile websites that offer access to good information, which require registration of users, so having some Yahoo email addresses will also likely come in handy later on. WB .......... metalworking projects www.kwagmire.com/metal_proj.html "Ken Sterling (Ken Sterling)" wrote in message ... Sorry everyone.... for some unknown reason... I didn't get the original post or the original responses. I know they made it through, cause I saw them on the Google newsgroups at work (but I'm not set up to post there). I didn't get them at home, but I did get the posts under the header Wondering how I can get Google to "send" the original headers and posts to my home computer.... any help here??? Thanks. Ken. -- Posted via a free Usenet account from http://www.teranews.com |
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