VFD's in home shop use

[Badasssapper67]

Hey everybody,
I don't have ANY vfd experience and was wondering how they are set up in a "home shop". Is it required that each machine has it's own vfd, or can several machines be hooked to it as long as one machine at a time is used?

Also, If you have a 5hp vfd because you're eventually going to get your big old air compressor going, can you run smaller motors on a big vfd? Say for instance a 1-3hp motor on a vfd sized for a 5hp motor?

I ask because I don't really know HOW a vfd does what it does and it's really not as important right now as getting my new mill drill up and running.

Thanks for the help.

 

[Gokart]

Hey everybody,
I don't have ANY vfd experience and was wondering how they are set up in a "home shop". Is it required that each machine has it's own vfd, or can several machines be hooked to it as long as one machine at a time is used?

You "could" do this, but I wouldn't recommend it. Vfd's have thermal protection built into the drive, so you would need to externally protect each motor.


Also, If you have a 5hp vfd because you're eventually going to get your big old air compressor going, can you run smaller motors on a big vfd? Say for instance a 1-3hp motor on a vfd sized for a 5hp motor?

You can use a bigger vfd on a smaller motor. You will just need to setup the drive to match the motor. I wouldn't try and run a 1 hp motor on a 25 hp drive though.


I ask because I don't really know HOW a vfd does what it does and it's really not as important right now as getting my new mill drill up and running.

http://www.vfds.com/blog/what-is-a-vfd

 

[bczygan]

One for each.

It's a pain to reset parameters when switching machines.

And they're cheap.

 

[Badasssapper67]

Awesome info!

 

[Badasssapper67]

I suppose the standard place to get them is ebay?

 

[zkling]

Do some reading on the topic and then come back and ask specific questions. Not trying to be an *** but this gets covered all the time and is not quite that simple for a all cases blanket assessment. As with any design choice there is a tradeoff. As typical with home or small shop equipment the tradeoff becomes money.

If you want a specific recommendation on a vfd for a specific motor/application that is one thing, but to sit and describe the theory and application choices is another.

 

[Hephaestus29]

You might try watching "Craig Chamberlain"
videos, he works for "precision electric" and
if you search the company name you
should also see his videos. The type of
VFD is a "Lenze" I bought the 3 hp version.
Anyway he does a good job of explaining
how the units work, wiring etc.

Another Guy who has bought these VFD's is " shadon HKW " he has a youtube video about them. He has one on just about everything he has and shows how they work etc.

 

[Gokart]

I am a big fan of the Square D 312 for small motors.

 

[fnieto]

Check automation direct, they have many to choose from for different applications.

 

[928'er]

Standard rule for acronyms:

Spell it out the first time you use it....

 

[pcmeiners]

"Standard rule for acronyms:
Spell it out the first time you use it...."
Unexplained acronyms, the new irritating affliction around here. Most of us have balls around here but crystal balls are in short supply.

VFD... some can save the settings for different motor setups on a USB flash drive for easy switching of motor, each USB proprietary drive is not cheap, setting can be saved on computer if the VFD has an ethernet interface.

 

[zkling]

Standard rule for acronyms:

Spell it out the first time you use it....

"Standard rule for acronyms:
Spell it out the first time you use it...."
Unexplained acronyms, the new irritating affliction around here. Most of us have balls around here but crystal balls are in short supply.

VFD... some can save the settings for different motor setups on a USB flash drive for easy switching of motor, each USB proprietary drive is not cheap, setting can be saved on computer if the VFD has an ethernet interface.

Dare I suggest if there is something you don't understand you make the slightest amount of effort and look it up? Google can always be a tab away. I know I know, there are leaders and there are followers.

Seems a bit hypocritical, no?

I recently picked up a new (to me) carbon fiber bike which has lots of small allen head fasteners with very precise (and low) torque spec's.

I have a nice SO 1/4" torque wrench, but all my hex sockets are either 3/8" or 1/2" drive. Can anyone recommend a decent set of hex sockets in 1/4" drive?

I suppose I could just use a 1/4" to 3/8" adapter, but where's the fun in that...?

 

[Mr. T]

Small VFDs are great and pretty affordable. Once you hit 3-5hp your wallet will start to hurt.

Another thing to consider is that they usually need a fused disconnect.

Is it possible to use one drive for multiple motors? Sure, but it's more trouble than it's worth.

 

[Ign]

Dare I suggest if there is something you don't understand you make the slightest amount of effort and look it up? Google can always be a tab away. I know I know, there are leaders and there are followers.

Seems a bit hypocritical, no?

Search should be SOP!

 

[tool_scrounge]

VFDs do not like having any switches between them or the motor. Opening or closing a switch when the VFD is on can damage the VFD. If you you have a multi speed motor on a lathe and a lot of relay controls, a rotary phase converter may be a better choice.

 

[928'er]

Seems a bit hypocritical, no?

Got me.

But with nearly 14,000 posts you can't figure out that SO is short hand for Snap On? Seems like every other post on here is about SO (Snap On).

VFD, not so much...

"Abbreviations not generally known should be followed in the text by the spelled-out forms in parentheses the first time they occur;..." (emphasis added) Webster's Encyclopedic Unabridged Dictionary of the English Language, A Manual of Style, p1746.

 

[joelowrider]

Yes you can oversize a drive for a smaller motor we do this all of the time everyday it is better to run a bigger drive and set the overloads down in it . I don't know about all but every drive I have used you set the full load amps on the drive for motor protectio
n

Here is something alto of people do not know about but Allen Bradley makes a single phase drive to run a 3 phase motor. I have 2 of these in use right now if someone wants part numbers I can get these Monday

This works out well when you have a 240 volt panel at your house and you buy a machine that has a 3 phase motor at like 480 or 230 volts

 

[Mr. T]

Here is something alto of people do not know about but Allen Bradley makes a single phase drive to run a 3 phase motor.

I thought that was the main advantage to running a VFD at home... Since very few people have 3 phase service at their house. And VFDs don't run single phase motors.

Also, while AB stuff is top notch, just about everyone that makes drives has single to three phase units.

 

[joelowrider]

I thought that was the main advantage to running a VFD at home... Since very few people have 3 phase service at their house. And VFDs don't run single phase motors.

Also, while AB stuff is top notch, just about everyone that makes drives has single to three phase units.

you can run a drive on single phase motors there are some issues but it can be done but most anyone would just change out the motor

I did not know anyone else made single phase to 3 phase drives we use 99% ab

we junk any square d telemecanique junk the second we can square d makes a great soft start but they should stay away from drives

cuttler hammer drives are ok we have someother odd and end drives but most are ab

I think we have something like 800-1000 drives on site
from little 1hp to 1000 hp
mainly 480vac
we have a few (meduim voltage) 4160vac and 13800vac units also

 

[joelowrider]

I thought that was the main advantage to running a VFD at home... Since very few people have 3 phase service at their house. And VFDs don't run single phase motors.

Also, while AB stuff is top notch, just about everyone that makes drives has single to three phase units.

http://www.invertekdrives.com/variable-speed-drives/optidrive-e2-single-phase/

 

[Mr. T]

http://www.invertekdrives.com/variable-speed-drives/optidrive-e2-single-phase/

Well, you learn something new everyday. Thanks for sharing.

About two months ago I salvaged some 1/2hp single to three phase Siemens drives that were about 20 years old. I'm sure they were state of the artish when used.

Also got a little Siemens PLC unit. Now if only there were someone that knew how to program it...

 

[Badasssapper67]

All righty then. It is mind bending trying to trace who is making the new ones now a days let alone if any of the Chinese made units are better than others.
My rule of thumb is to spend the money were the money matters. I wouldn't buy a snap on pressure washer but I danged sure got snap on pry bars and cold chisels. When it comes to the vfd's there are those made by companies Ive heard of before like Mitsubishi and they're double of the no name, roll the dice units, but is it for a reason? Ive got a 3hp motor on my mill drill and a 5 hp motor on my project air compressor.
Based on the advice here theyre getting their own units. Unless someone has specific experience with buying units from a specific seller Im just going to go by instinct and hope they're good.

 

[Gotcha640]

My local VFD will inspect child car seats, and they might still recharge fire extinguishers. I help with a group that does a barbecue, Thanksgiving, and Christmas dinners at the station. We also did a tour when I was in Scouts.

Not sure many of us have room for the trucks though, especially if you want them literally IN your home.

My VFD is best VFD because barbecue and neighborhood outreach.

End troll.

 

[joelowrider]

Well, you learn something new everyday. Thanks for sharing.

About two months ago I salvaged some 1/2hp single to three phase Siemens drives that were about 20 years old. I'm sure they were state of the artish when used.

Also got a little Siemens PLC unit. Now if only there were someone that knew how to program it...

I could program it for you. You would have to send it to me but not a big deal

 

[joelowrider]

All righty then. It is mind bending trying to trace who is making the new ones now a days let alone if any of the Chinese made units are better than others.
My rule of thumb is to spend the money were the money matters. I wouldn't buy a snap on pressure washer but I danged sure got snap on pry bars and cold chisels. When it comes to the vfd's there are those made by companies Ive heard of before like Mitsubishi and they're double of the no name, roll the dice units, but is it for a reason? Ive got a 3hp motor on my mill drill and a 5 hp motor on my project air compressor.

Based on the advice here theyre getting their own units. Unless someone has specific experience with buying units from a specific seller Im just going to go by instinct and hope they're good.

Depending on how often you would use You could use one drive and change a few peramaters

If it was me and I am cheap I would use 1 drive program it to protect the 5hp motor like 7.8 full load amps the 3 hp is like 5 amps not a big difference the drive is still going to protect the motor to a extent

I would run a start stop button on each piece of equipment I would take the output of the drive to a transfer switch so only 1 motor would run at a time

 

[bczygan]

I have a TECO N3-203-CSU for 3HP 240V 1PH to 3PH
http://dealerselectric.com/images/Products/teco/n3_compact_drive.pdf

$291.00

Hitachi also makes good drives.

Think about the enclosure you might need and consider a removable face and a pot integral with the unit.

Programming is the fun part.

Bill

 

[mikegt4]

I have two Teco VFD drives for my mill and lathe. They work great and are not all that expensive. For my Millrite I use a Teco with a Speed Potentiometer knob for easy speed changes. For my Weiler lathe, which has a gazillion speeds, I used a more basic Teco with just a touchpad speed adjustment which I never had to use.

Make sure that you get a VFD that is rated for your motor HP, input voltage and output requirement.
I got my VFD units from Dealers Electric, good prices and service.

 

[454ragtop]

Have many VFD's in use, providing single to 3 phase, and variable speed on machine tools, they work excellent. For the compressor, I would highly recommend swapping the motor to a single phase unit rather than using a VFD. One large enough for the high load of 5 HP motor on a compressor is likely to cost more than a single phase motor. Would be possible to use a VFD on more than one tool if it was wired to a 3 phase outlet, and then you wired the motors with a 3 phase plug, with no switches between. Then unplug one motor, and plug in a different one, they only run 1 motor at a time.
HTH, Jim

 

[kevinb77777]

Another way to do this is to use a 240 volt 3 phase to 3 phase VFD and only use single phase as the input. Doing this though will require you to derate the VFD by 50 %. Above 3hp it is difficult to find a single phase to 3 phase motor.

As an example, I have a 5hp 3 phase air compressor running on single phase 240 volts. I use a 10 hp 3ph to 3ph VFD. Make sure the VFD has a speed adjustment on the front of the unit and you can vary the speed as required. I used an Allen Bradley VFD and it has been in use for about 5 years. since the compressor utilizes a 3600 rpm motor, I slow it down to 50% when I am not using the full capacity of the air compressor.

The theory behind it is a VFD takes the input AC voltage and converts it to DC before then converting back to AC. So running the VFD on single phase could overload the ac-dc conversion, therefore derating the VFD by 50% allows this.

3 phase to 3 phase vfd's @ 240volt are much cheaper and readily available on the used market than a single phase to 3 phase type.

One other warning about using any VFD. Most motors if they are not an inverter (another word for an VFD) rated motor shouldn't be run under 20% of their rated speed. When a motor is run at a slower speed via reducing the frequency the impedance (AC resistance) is much lower than at rated speed and you could overheat and burn out the windings.

I am an electrical engineer in a manufacturing plant and use VFD's everyday.

Kevin

 

[Badasssapper67]

Depending on how often you would use You could use one drive and change a few peramaters

If it was me and I am cheap I would use 1 drive program it to protect the 5hp motor like 7.8 full load amps the 3 hp is like 5 amps not a big difference the drive is still going to protect the motor to a extent

I would run a start stop button on each piece of equipment I would take the output of the drive to a transfer switch so only 1 motor would run at a time

I went a head and ordered two volunteer fire departments. One for the 5 hp and one for the 3hp. If there's a way that I could've run them both off one I will tell you guys.

 

[kevinb77777]

Keep in mind just because you have a 5 hp motor doesn't mean it draws current of a 5hp load. Many times a designer of the machine will have a big safety factor and upsize the motor. Check and see the actual running current with an Amprobe ( orsimilar current measuring device) of the larger motor. It may surprise you that it is much less than FLA (Full Load Amps). If it is you could run the 5 HP motor with a smaller vfd. VFD's are really rated for their output current, HP is just a good rule of thumb. Keep in mind you can always run a smaller motor on a larger VFD by adjusting the trip current within the VFD for the smaller load.

Most VFD's also have a setting to boost startup torque and also have a soft start so the motor can be spooled up slowly instead of a instant on and loading down a circuit so your house lights flicker on startup of the motor.

A VFD is an excellent motor and overload protector. The old style motor starters with its alloy overloads will never be as good as an electronic overload system as in the VFD.

All that and you have a way to vary the speed if required. Just remember the 20% rule for non-inverter rated motors.

Kevin