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Old 05-12-2008, 09:45 AM   #1
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110v vs. 220v


I am a total novice and semi electrically illiterate. I have a lathe, which has a 110v,1-phase, 3/4 hp, 1725 rpm motor. Changing spindle speeds is a PITA, requiring changing belt positions on stepped-pulleys and/or changing gears. Even then, I cannot get the extremely slow speeds I would like for some operations. So, searching, googling, etc., I've decided the best solution to my problem (so I would have low-rpm torque) is to replace the motor with a 3-phase motor and control the rpm with a variable frequency drive (VFD). I obtained a 3-phase, 1hp, 208/460v, 1725rpm motor at a garage sale for $25. I am ready to order the VFD and have decided a Teco/Westinghouse FM-50 VFD would be suitable. These units are available with either a 110v, 1-phase or 220v, 1-phase input and 208-230v 3-phase output, for approximatley the same price. I presently have 110v at the lathe, but could easily run a 220v branch circuit. So, my question (finally), are there any advantages/disadvantages making it preferrable to using one voltage over the other??

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Old 05-12-2008, 10:33 AM   #2
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110v vs. 220v


I am a bit of a newbie also, but believe if you want 3 phase 208v, you may need an additional wire(s?) run from your service provider, whereas with 1 phase 240 you should be able to do that assuming you have space available for a branch circuit breaker (?) The experts will chime in...

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Old 05-12-2008, 01:19 PM   #3
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110v vs. 220v


My comments in blue.

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Originally Posted by gunboatbay View Post
I am a total novice and semi electrically illiterate. I have a lathe, which has a 110v,1-phase, 3/4 hp, 1725 rpm motor. Changing spindle speeds is a PITA, requiring changing belt positions on stepped-pulleys and/or changing gears. Even then, I cannot get the extremely slow speeds I would like for some operations. So, searching, googling, etc., I've decided the best solution to my problem (so I would have low-rpm torque) is to replace the motor with a 3-phase motor and control the rpm with a variable frequency drive (VFD). I obtained a 3-phase, 1hp, 208/460v, 1725rpm motor at a garage sale for $25.

Have you carried out an insulation resistance test on this "2nd hand" motor to verify its' possible future life? If not, you should do so immediately. This test should be carried out by an electrician. This test is not required for new motors.

Also, if you plan to supply this motor via a VFD, the motor insulation should be at least Class F (or "Inverter Duty" Class). If it isn't & if the motor is in poor condition (poor insulation resistance), you may very well expect a very short life from the motor.

Further, the motor should not be operated at less than 25% of its' rated maximum speed (cooling). Usually, extra cooling (electric fans) is provided for such motors.

I'm curious as to what the "208" motor voltage pertains to. Is the motor "WYE" (Star) connected for this voltage? This could be important.

I am ready to order the VFD and have decided a Teco/Westinghouse FM-50 VFD would be suitable. These units are available with either a 110v, 1-phase or 220v, 1-phase input and 208-230v 3-phase output, for approximatley the same price. I presently have 110v at the lathe, but could easily run a 220v branch circuit. So, my question (finally), are there any advantages/disadvantages making it preferrable to using one voltage over the other??
I'll bet you never thought that this could become so complicated.
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Old 05-12-2008, 01:59 PM   #4
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110v vs. 220v


You seem like you know more that you think. The VFD is the best way to go. Not only can you decrease speed but you also can go above nameplate rpm. (with considerations) Also, at 1.5 hp, no single phase derate is needed.
Elk is correct about the motor. But I would recommend class "H" magnet wire minimum. If the motor you bought is relatively new it may even have inverter spike resistant wire in it already. Most all major motor manufacturers have been using the inverter wire for about 5 years now. Baldor uses it across the board for at least 6 years.

What is the frame size required??????????

A standard NEMA 1.5 hp motor at 1800 rpm is on a 145T frame. Is this the frame size you have?
Run the motor you have until it gives out then you can buy a new one very inexpensive.
I am looking at a Weg motor catalog right now and if the motor is on a 145T frame it will cost you about $150 retail. This is a premium efficient motor and suitable for inverter use.
If you plan to run the motor at slower than 1/2 speed, you should lookat a (TEBC) frame. It is a forced blower that will run at full speed while the motor can run at any other speed. It will have its own power source, seperate from the motor.
TECO is a pretty good drive. Very similar to Magnetek.

Check the following for drive prices and functionality:
www.wegelectric.com
www.automationdirect.com
www.baldor.com
www.tecowestinghouse.com

Note: Use a .50 multiplier against the list price in the catalogs. This will give you a good idea what each motor will cost you. Look at it as the high price and not the low price as it could be much lower depending on manufacturer and supplier.
Example: List price in catalog is $100. Multiply 100 x .50 = your cost $50.00

PS........Use 240 volt single phase. Stay away from 120 if possible.

Last edited by J. V.; 05-12-2008 at 02:02 PM.
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Old 05-12-2008, 06:01 PM   #5
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110v vs. 220v


240 is advantageous for two reasons. first it only requires half of the current for the same load this in turn makes that you can run smaller cheaper wires. second it only requires roughly one quarter of the watts therfore saving money on your electric bill.
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Old 05-12-2008, 06:10 PM   #6
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110v vs. 220v


Uhhhh...do you have 3 pase power available in your building?
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Old 05-12-2008, 08:16 PM   #7
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110v vs. 220v


Quote:
Originally Posted by Pudge565 View Post
240 is advantageous for two reasons. first it only requires half of the current for the same load this in turn makes that you can run smaller cheaper wires.
This is true.


Quote:
Originally Posted by Pudge565 View Post
second it only requires roughly one quarter of the watts therfore saving money on your electric bill.
This is unbelievably FALSE!!!
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Old 05-12-2008, 08:19 PM   #8
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110v vs. 220v


Gunboat,

Going from "110v to 220v" is all well and good, but you want to go from 120V single phase to 240v THREE-PHASE. BIG, BIG difference. It is WAY more than having additional wires run from the POCO.

I'll ask the same as 220/221....do you even have three phase in your building/home???? If this is your home I seriously doubt it.

If this is a business or commercial site then CALL AN ELECTRICIAN.
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Old 05-12-2008, 09:18 PM   #9
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110v vs. 220v


The OP doesn't want to run 3 phase to his home, he wants to buy a single phase to 3 phase converter.

And Pudge is just a student, so tell him where he was wrong instead of just ripping on him.

Pudge, I believe you were thinking of "I squared R" losses which wouldn't apply in this situation.
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Old 05-12-2008, 11:28 PM   #10
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110v vs. 220v


First of all, I'd like to thank everyone for their assostance and responses to my question. Some of your responses left me quite confused however. I do not have 3-phase power available at my home. The data available to me on the internet, specifically states that the TECO/Westinghouse FM-50 VFD input is single-phase (either 110v or 220v, depending on the model) and the output is three-phase. I downloaded the FM50 manual and verified this, knowing that getting 3-phase power to my residence, or purchasing a phase-converter, would be an expensive proposition.
After I obtained the motor from a garage sale, I was skeptical of its condition, so I took it to a motor repair facility in town, explained to them what my plans were and asked them to check out the motor. They ran it, checked it and told me it would be suitable for what I wanted to do. They weren't familiar with the VFD, so couldn't help me with that. The motor is a "Doerr, Emerson Electric", Model LR22132, with a XG56H Frame.
After reading your responses, I will order the 220v input VFD and run a 220v circuit to the lathe area, rather than utilizing the existing 110v circuit. Thanks agin for your help.
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Old 05-13-2008, 01:15 AM   #11
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110v vs. 220v


You're going about this the right way, your plan will work. I'd use 220 as well.

If the existing motor is a 56 frame, the new one will fit. The 2 letters in front (XG in this case) are manufacturers designations, and don't really mean anything here. The number 56 means that the shaft is 5/8" diameter, 1 7/8" long, and the center is 3 1/2" up from the base. The mounting holes (slots) are 3" X 4 7/8". The H on the end means it has a combination mounting base, with holes (slots) at 3" X 4 7/8" and 5" X 4 7/8".

You'll need to program the drive, it has overloads built into it, and will need some motor info. The motor will be connected for low voltage (208-230), and you'll need 3 wires plus a ground between the drive and the motor. If the drive asks you # of poles (some do, some don't), all motors that operate between 1700 and 1800 RPM are 4 pole. 2 wire control = on-off switch, 3 wire control= start-stop buttons. Most of the other stuff can be left at factory settings.

Speed control can be accomplished via the keypad, or you can add a speed pot (potentiometer, a knob you turn like a volume control). You'll need a 3 wire shielded cable between the drive and the speed pot, and if you get a pot with a switch on it, you can click it all the way off (like the old radios and tv's). For that, you'll need 5 wires.

There are endless possibilities of how to control a drive, you'll just have to decide what works best for you.

Rob
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Old 05-13-2008, 10:10 PM   #12
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110v vs. 220v


silk i was just quoting what my shop teacher said although he was talking about base board heaters. does it apply to that is is that statement totaly unfounded. ive had this problem before with my shop teacher giving me misinformation.
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Old 05-13-2008, 11:41 PM   #13
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110v vs. 220v


If you connect a 240 volt baseboard heater (or any other resistive load) to a 120 volt circuit, the current will be 1/2 as much, and the wattage will be 1/4 as much.

A dual-voltage motor however, requires re-connection to match voltage. The watts it consumes is dependent on the output of the shaft. Think of it this way; a 1HP 115/230 volt motor is actually two 1/2HP 115 volt motors contained in the same frame. If connected for 115 volts, the 'two motors' are paralleled. If connected for 230 volts, they're in series.

Each of the 'two motors' in his case will draw about 8 amps. In a parallel connection, voltage stays the same, and current adds. Thus we have 115 volts, and 16 amps. In a series connection, voltage adds while current stays the same. Thus we have 230 volts, and 8 amps.

To keep it simple, we'll not consider power factor or efficiency here. Ohms law tells us that watts = volts X amps. 115 X 16 =1840. Likewise, 230 X 8 = 1840. Same power consumption on either voltage.

Now, back to the heater. Lets say this heater draws 4 amps at 240 volts. That would be 960 watts. Ohms law further states that volts divided by (sorry, I don't have a 'divide by' symbol on my keyboard lol) ohms (resistance) = amps. In this case, the heater is 60 ohms. 240 volts divided by 60 ohms = 4 amps. Now, lets apply 120 volts to the heater. We haven't re-connected it, so the resistance is still 60 ohms. 120 volts divided by 60 ohms = 2 amps. 2 amps X 120 volts = 240 watts.

As you can now see, re-connecting a dual-voltage load makes a huge difference in its power consumption.

Rob
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Old 05-14-2008, 09:14 AM   #14
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110v vs. 220v


Pudge, everything Micromind said is correct. In the trade we have a term called "I squared R losses", it's just Ohm's law
"W=I squared R" (sorry I don't know how to superscript the number 2 for squared)

You're shop teacher was supposed to be reffering to the wattage being 1/4 in his baseboard example, if you take a 240 volt baseboard heater and reconnect it to 120 volts you will have 1/4 the wattage output. That is because you are not changing the resistance of the heater.
When we reconnect motor windings from series for 240 to parallel for 120, we reduce the R in our formula so our wattage (Horsepower) remains the same, although our amps is doubled.

"I squared R losses" are the reason your utility lines run at such a high voltage. If you run at a higher voltage, the amps can be greatly reduced. Since all conductors have some resistance, if you can reduce the I (amps) then you can significantly reduce the power lossed on your utility lines.

P.S. You just need to play around with all the different ways you can transpose ohms law and everything will click and you will be better at this than the largest majority of electricians.

Last edited by Silk; 05-14-2008 at 09:32 AM. Reason: added ps
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Old 05-14-2008, 10:24 AM   #15
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110v vs. 220v


To Silk,
Hold down the Alt key and type 0178 to get the squared () symbol. It works 50% of the time.

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