VFD Advice

[Daves69]

Just bought a Sharps 1740 Lathe and need a VFD to power the motor. 7.5 hp 20a. This is my first attempt a using a VFD. Where to purchase and what size? I am also planning to wire a mill 2 hp 2a can I use the same VFD or do I need a second one?

 

[wyliesdiesels]

Need more info.

What voltage service do u have and is it 3phase?

Do u have a link to the lathe specs?

 

[Daves69]

I have 220v 1 phase residential service

can't find a link to the lathe specs Sharp 1740k 7.5 hp 20a 3 phase

 

[tailshaft56]

Here is where I bought mine. They answered all my questions and the unit shipped promptly.

 

[Daves69]

Here is where I bought mine. They answered all my questions and the unit shipped promptly.

Please post link

 

[danb35]

I've bought VFDs from www.factorymation.com and been pleased with their prices and service. You probably won't find a single-phase-input VFD that can handle 7.5 HP. But you can buy a larger unit (probably 15 HP), and feed it single-phase power, and it should work fine.

 

[DpSyChO]

@Daves69................Hello neighbor....
Driveswarehouse has what you seek but it's around $1K.
https://www.driveswarehouse.com/pc1-75-2124

 

[wyliesdiesels]

I have 220v 1 phase residential service

can't find a link to the lathe specs Sharp 1740k 7.5 hp 20a 3 phase

Is it 240v 3 phase? or 480v 3 phase?

From what i recall u wont find a VFD that does single phase in with that much HP rating..

Your best bet is to buy or make an RPC...

 

[wyliesdiesels]

I've bought VFDs from www.factorymation.com and been pleased with their prices and service. You probably won't find a single-phase-input VFD that can handle 7.5 HP. But you can buy a larger unit (probably 15 HP), and feed it single-phase power, and it should work fine.

largest single phase input drive they have is 10.5FLA which is about 3.5hp 3 phase 230v...

 

[Dr Stan]

I'm a half way decent 2 wire electrician, but with limited 3 phase experience. There is a guy who builds phase converters under the brand name Phase Craft and sells them on Ebay. He was very good to work with and diagnosed a problem via e-mail and sent the components I needed at no cost to me.

As I understand it you will need a 15hp 3 phase motor to serve as the generator to support 7.5hp 3 phase. Here's his 7.5hp unit on Ebay: http://www.ebay.com/itm/Phase-Craft...hash=item45ffc14ddb:m:mJpirv7csiTFsZ9LE76vfmA

No connection other than a satisfied customer.

 

[wyliesdiesels]

@Daves69................Hello neighbor....
Driveswarehouse has what you seek but it's around $1K.
https://www.driveswarehouse.com/pc1-75-2124

Loos like that one is NOT U/L listed.

And he will need a 60a circuit to power it.

 

[dave lewis]

You need a 3 phase vfd rated for twice your horsepower..so 15 hp..
You can feed it single phase..
It will output 3 phase..

I read up on doing this..really did not believe it would work..
When I wired up my Bridgeport mill..held my breath...WOW..it works great !
After more research...now I understand why it works..
The VFD stores the input energy in capicitors....
And releases it according to the settings you program..
Thats how the vfd can soft/slow start..and reverse..and soft/slow stop etc..
So...220 single phase input populates all 3 capacitors..
The double sizing is a safety factor to make sure you do not overload any one capacitor..
Used VFD 's all over eBay for cheap..
Dave

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[nsula_country]

You need a 3 phase vfd rated for twice your horsepower..so 15 hp..
You can feed it single phase..
It will output 3 phase..

I read up on doing this..really did not believe it would work..
When I wired up my Bridgeport mill..held my breath...WOW..it works great !
After more research...now I understand why it works..
The VFD stores the input energy in capicitors....
And releases it according to the settings you program..
Thats how the vfd can soft/slow start..and reverse..and soft/slow stop etc..
So...220 single phase input populates all 3 capacitors..
The double sizing is a safety factor to make sure you do not overload any one capacitor..
Used VFD 's all over eBay for cheap..
Dave

Sent from my SAMSUNG-SM-G891A using Tapatalk

This is correct for SOME VFD units. Some can take 1p or 3p input and output 3p. SOME CANNOT!

Interestingly many import drives can support only 1p input. Industrial MFG's like A-B, Mitsubishi and Siemens are 3p in 3p out only... Read the fine print before purchase!

If you find a 15HP VFD that can take 1p input, you are in business!

Let us know what you find!

CT

 

[mm08822]

Is the motor 480vac or 240vac? A 240vac input to the drive will not output 480vac to motor. Maybe motor is dual voltage. If so what are respective currents?

I doubt your going to find a single phase input drive capable of delivering enough power for 7.5 hp.

 

[A_Pmech]

If you have multiple machines, a rotary phase converter would be more in line with your needs.

 

[mikegt4]

I have purchased a couple of VFDs from Dealers Electric and am happy with the units and the company. Make sure that you get a unit with the correct input and output specs that you need. Most places will help you with which units will work for your situation. Better to ask BEFORE you buy.

http://dealerselectric.com/default....tm_campaign=Constant+Contact&utm_medium=email

 

[walta]

Do you need that much horse power?

If this is a hobby, take lighter cuts and run a smaller motor. If you can get by with 3 HP the prices of VFDs become affordable.

Most VFDs need to be programmed to match the motor. The drives are not easy or fun to program so unless both motors are very similar people end up with 2 drives.


Walta

 

[Daves69]

Thanks for the education on this subject. I am going with a rotary converter. This will power both the mill and the lathe. I will let you know how this works out.

 

[kaffine]

This is correct for SOME VFD units. Some can take 1p or 3p input and output 3p. SOME CANNOT!

Interestingly many import drives can support only 1p input. Industrial MFG's like A-B, Mitsubishi and Siemens are 3p in 3p out only... Read the fine print before purchase!

If you find a 15HP VFD that can take 1p input, you are in business!

Let us know what you find!

CT

Just wondering is it that they wont work with 1ph input or that they don't support it so if you try and have issues you are on your own? I don't see them running multiple DC busses inside.

 

[wyliesdiesels]

Thanks for the education on this subject. I am going with a rotary converter. This will power both the mill and the lathe. I will let you know how this works out.

what voltage do the machines run on?

 

[Daves69]

The lathe runs on 220 3ph and the mill runs on 220 or 440 3ph.

 

[mm08822]

The lathe runs on 220 3ph and the mill runs on 220 or 440 3ph.

So the mill mtr probably needs to covert to 220v so you only have 1 voltage to contend with.

 

[mm08822]

Just wondering is it that they wont work with 1ph input or that they don't support it so if you try and have issues you are on your own? I don't see them running multiple DC busses inside.

A 3 phase input will provide a higher dc buss voltage internal to the drive than will single phase. Buss voltage is typically monitored for min and max values. If the buss falls out of that permitted range, it can cause a drive fault. So some of the reason is firmware programming and the other is available power within the dc capacitor bank available fur output pulse width modulation.

 

[wyliesdiesels]

The lathe runs on 220 3ph and the mill runs on 220 or 440 3ph.

you should convert the mill to run on 240v. 480v is NOT a DIY voltage.

If you dont know what you are doing you can have bad things happen.

 

[nsula_country]

Just wondering is it that they wont work with 1ph input or that they don't support it so if you try and have issues you are on your own? I don't see them running multiple DC busses inside.

I have researched this, some.

Many of the import drives will take 1p input, but the drive is derated. 3p input, full nameplate load.

Derating rule of thumb is take motor FLA * 1.73. This is the size drive needed to run a 3p motor on a VFD that will take 1p input.

I spoke with my Allen-Bradley salesman about this one day. A-B drives, to his knowledge were 3p input, 3p output only. But these are legit, industrial, continuous duty drives with a price tag to match.

In a nutshell, the way a drive works is line voltage is fed in, then it is rectified to DC. This DC is then inverted back to AC under frequency control on the load side. On a 480v drive the DC bus can be as high as 680-720 vdc.

FYI, I am an Automation Controls Engineer. I do not work with VFDs a lot. BUT deal with ALOT of servo drives.

I would rather have a VFD on my lathe or mill than run a RotoPhase.

CT

 

[kaffine]

A 3 phase input will provide a higher dc buss voltage internal to the drive than will single phase. Buss voltage is typically monitored for min and max values. If the buss falls out of that permitted range, it can cause a drive fault. So some of the reason is firmware programming and the other is available power within the dc capacitor bank available fur output pulse width modulation.

I don't see how 3 phase would provide a higher voltage as that would be determined by the peak to peak voltage which would be the same. I can see less ripple but that is what the capacitors are for. I can see needing to oversize the drive if running from 1ph as you would have more current going through parts than if run on 3ph.

 

[mm08822]

I don't see how 3 phase would provide a higher voltage as that would be determined by the peak to peak voltage which would be the same. I can see less ripple but that is what the capacitors are for. I can see needing to oversize the drive if running from 1ph as you would have more current going through parts than if run on 3ph.

There is a practical limit to filtering out the ripple. Could it be done, yes. Mfr's must not believe there is enough demand.
See attached. These are random graphs I grabbed so all variables are not consistent from pic to pic.
View attachment VDC_Buss_Voltage.pdf

 

[Bert_]

The reason the drive must be de-rated is so the rectifier's on the inputs can handle the additional current that the drive will draw on single phase. (same amount of power divided over 2 lines vs. 3)

The input current can be calculated by taking the FLA of the motor and multiplying by 1.73. Your scenario with a 7.5 hp motor drawing 20A, The circuit feeding the VFD will need to be sized for a load of 34.6A.

VFD's can usually only operate one motor. You must program the drive to each motor so it doesn't make much sense swapping it back and forth.

To my knowledge most drives will accept single phase input. My supplier has never said anything about a special type of drive, just that we must oversize it. I have installed several on large motors (20-60hp) where 3 phase was not available or would have required several miles of line to be rebuild mostly at the customers cost ($$$)

 

[nsula_country]

The reason the drive must be de-rated is so the rectifier's on the inputs can handle the additional current that the drive will draw on single phase. (same amount of power divided over 2 lines vs. 3)

The input current can be calculated by taking the FLA of the motor and multiplying by 1.73. Your scenario with a 7.5 hp motor drawing 20A, The circuit feeding the VFD will need to be sized for a load of 34.6A.

VFD's can usually only operate one motor. You must program the drive to each motor so it doesn't make much sense swapping it back and forth.

To my knowledge most drives will accept single phase input. My supplier has never said anything about a special type of drive, just that we must oversize it. I have installed several on large motors (20-60hp) where 3 phase was not available or would have required several miles of line to be rebuild mostly at the customers cost ($$$)

I brought this up to our A-B rep and A-B drive specialist when they stopped by the plant today. The old 1331, 1334, 1336 (sic) could take 1p input. Once the PowerFlex 7, 70, and 700 came out they are 3p input only.

The drive guy said it was because of how the SCRs fire in the PowerFlex series drives. Makes sense if the firing board is setup to work on 3p only. Essentially it would detect a loss of phase.

CT

 

[manwithtools]

I brought this up to our A-B rep and A-B drive specialist when they stopped by the plant today. The old 1331, 1334, 1336 (sic) could take 1p input. Once the PowerFlex 7, 70, and 700 came out they are 3p input only.

The drive guy said it was because of how the SCRs fire in the PowerFlex series drives. Makes sense if the firing board is setup to work on 3p only. Essentially it would detect a loss of phase.

CT

I think you need to get a new drive specialist that knows how to read a manual. There are many versions of PowerFlex drives that will operate on single phase input. They will need to be de-rated just as any other drive, but many of them will allow single phase input - specifically the PowerFlex 500 and 700 family.

I can't stand supposed product specialists who don't know their products. To be clear my comment is not directed at you, but at your Rockwell guys.

 

[nsula_country]

Interesting... I'll research, and if true, I'll call him out on that. I spend obscene amounts of company money on Rockwell products...

Reminds me of the Rockwell Automation slogan... "You can find better, but won't pay more!"

Thanks,

CT

 

[slow]

I've used Schneider Electric Altivar (either 61 or 71, I think 71) VFD's on several 7.5 hp motors, they had to be upsized to 10hp drives and in settings disable phase loss detection. It is also a good idea to run a line reactor, essentially a 1:1 transformer to prevent interference back to the rest of the system.

 

[nsula_country]

Line reactor is recommended for ANY VFD or servo drive... I've noticed drives with reactors live much longer!

CT

 

[mm08822]

Interesting... I'll research, and if true, I'll call him out on that. I spend obscene amounts of company money on Rockwell products...

Reminds me of the Rockwell Automation slogan... "You can find better, but won't pay more!" and that slogan came from within Rockwell

Thanks,

CT

I'll save you some leg work and give you some stones to throw... Powerflex series:
750 series derates 3phase hp to 50% for single phase input
520 series same hp for 240vac single and three phase inputs at low hp's
523,525 series 3 phase input provides full hp while single phase provides only 35% rated hp
527 series same hp for 240vac single and three phase at low hp's
(I can provide several screen shots from tech manuals if you like)

When there is an option to order a single phase input on AB drives, the frame size goes up quickly from A to B as compared to 3 phase input drives for the same hp. (This means bigger diodes, resistors, caps on the rectifier/buss stages in single phase from ends. This is how they are raising the DC buss voltage - more filtering, less ripple.

For those drives that do not upsize the front end hardware, they derate the overall rating of the drive to keep those components within their design limits.

A said several times before, you must review the drive specs for input ratings and how (if) they affect the HP(kw) rating.

 

[manwithtools]

Line reactor is needed in certain situations, it's a design consideration but not a necessity. Once again, its important to read and understand the manual and the application.

 

[manwithtools]

Interesting... I'll research, and if true, I'll call him out on that. I spend obscene amounts of company money on Rockwell products...

Reminds me of the Rockwell Automation slogan... "You can find better, but won't pay more!"

Thanks,

CT

I did the research, that's why I replied the way I did. It's all available on a Google search which returns links to the manuals. I spend about $1M with them every year and integrate another $2-3M. Our folks know their products better than they do.

 

[nsula_country]

I'm more of a PLC, HMI guy than motion control. I have had most of my experience with Emerson and Control Techniques servo drives. Minimal AB servo experience.

Recently gutted 4 machines, total overhaul, mechanical and controls. I was the sole controls engineer. PLC5 to CompactLogix, CT FX to EP-P, ESAB welding power supplies to Fronius, PanelView Classic to PanelView +6... Went from DH+, DeviceNet, discrete to EthernetIP. All in house integration. Took one down at a time during production. 6-7 weeks of HELL! Only help I had was contract electrical for I/O and local integrator to assist with HMI while I did the rest.

In a previous employment, I replaced many Mitsubishi and Reliance drives with PowerFlex 700's. All 480 3p. Also worked with MANY Siemens servo drives, over Profibus, talking to Siemens 505... Even had some Texas Instruments 500 PLC... Ancient ****!

I will have a conversation with my AB guy, he visits weekly. I have used the "Can get better, but not more expensive" line with them before. Also have left PLC Center/Radwell Int'l boxes on my desk... They don't like that.

Thanks!

CT

 

[manwithtools]

I'm more of a PLC, HMI guy than motion control. I have had most of my experience with Emerson and Control Techniques servo drives. Minimal AB servo experience.

Recently gutted 4 machines, total overhaul, mechanical and controls. I was the sole controls engineer. PLC5 to CompactLogix, CT FX to EP-P, ESAB welding power supplies to Fronius, PanelView Classic to PanelView +6... Went from DH+, DeviceNet, discrete to EthernetIP. All in house integration. Took one down at a time during production. 6-7 weeks of HELL! Only help I had was contract electrical for I/O and local integrator to assist with HMI while I did the rest.

In a previous employment, I replaced many Mitsubishi and Reliance drives with PowerFlex 700's. All 480 3p. Also worked with MANY Siemens servo drives, over Profibus, talking to Siemens 505... Even had some Texas Instruments 500 PLC... Ancient ****!

I will have a conversation with my AB guy, he visits weekly. I have used the "Can get better, but not more expensive" line with them before. Also have left PLC Center/Radwell Int'l boxes on my desk... They don't like that.

Thanks!

CT

Sounds like quite a project. The upgrades should insure many more years of operation. The Rockwell stuff is expensive, but for the most part I've had good luck with it for the past 35 years. I just don't like their arrogance when it comes to their customers. They will compete with us in the marketplace for projects and then ***** to us when we don't increasing our purchase volume with them every year.

 

[A_Pmech]

I just don't like their arrogance when it comes to their customers.

I'm convinced it's part of the hiring process at Rockwell to screen out anyone who isn't a jerk.

 

[mm08822]

I'm convinced it's part of the hiring process at Rockwell to screen out anyone who isn't a jerk.

When they laid off lots of people in the then "GTS group" 10-11 years ago, they let all the smart ones go - the ones who got the equipment properly spec'd, programmed and running.

A lot of these people went out on their own and are still in business today, doing business with former Rockwell customers! Their rates were cheaper and better service.

The one's who were left didn't know anyof the products and were underwater for a couple years. We quit meeting with them. Don't call us, we'll call you!