Another VFD Question

R

Randydb

Joined
Sep 27, 2014
Messages
1,108
Came across 3ph motors for sale buried in a cragslist ad for backhoe buckets. Got a couple 2 hp 3ph 1725rpm Baldor motors for $50...total! The guy tears down old mills. It took a bit of digging but I got gold for next to nothing!

Now the VFD. I know I need 220v 1ph in 3ph out VFD. Preferably nema 4x or with a sealed box that still lets it cool.

My question is hp. Is the maximum hp vfd I can get 2hp? I know I could run less...like 1hp, but then that is the max output going to my motor.

Reason I am asking is I saw a 7hp vfd with a nema 4x rating(hope I said that right) go through craigslist for $200 a while back. Now I wonder if I can use one like that and they can be programmed to just put out 2hp.

Thanks
Randy Bates
 
Assuming you have the power supply to run the VFD, pretty much every VFD I've ever come across will run a smaller motor without problems. The current limit can usually be set to any value below maximum rating for the VFD on keypad-programmable VFDs. I'm not sure about the KBACs and similar which are mostly jumper-programmable, though I'd guess they'll use a pot to set the current limit and it'll be infinitely adjustable.

I was at the control panel builders we use for work a while back when they were testing a VFD panel before it went out. They were running a 90 W (1/8 HP) motor on a 110 kW (150 HP) VFD during the test.

As VFDs get bigger on small mains supplies, there comes a point at which the fuse or circuit breaker cannot cope with the inrush when the VFD is first energized and the fuse blows or the breaker trips.

Above about 3 HP, many 220V VFDs need a 3-phase input and just will not run on a single phase supply. Not all do, but it's something you will need to bear in mind when looking for one. Some will run on either single- or 3-phase power.
 
Generally VFD's can be had for quite large motors as well, and often they will work just fine for any motor of the HP rating or below. The KBAC 27 has a jumper that they recommend switching if using a lower HP motor, but I use my TECO FM50 interchangeably for several motors between 1 and 3 hp. I would say to research that about whatever particular VFD you may source.

For you, what will matter is phase conversion. Above 3hp it is uncommon to find VFD's that will take a single phase input. My TECO FM50-203-C is a 3hp model that takes single phase input, and it's great, but not NEMA 4 rated. Precautions are necessary.

I think of the VFD as a power supply, and run a bank of machines from it. It is power, and does not overly care how much is being drawn at a time, up to its limit.
The best way would be to have a 3 phase breaker box, run a hot leg from the VFD to each bus bar, and select machines by the use of breakers.
 
Salem Straub said:
Generally VFD's can be had for quite large motors as well, and often they will work just fine for any motor of the HP rating or below. The KBAC 27 has a jumper that they recommend switching if using a lower HP motor, but I use my TECO FM50 interchangeably for several motors between 1 and 3 hp. I would say to research that about whatever particular VFD you may source.

For you, what will matter is phase conversion. Above 3hp it is uncommon to find VFD's that will take a single phase input. My TECO FM50-203-C is a 3hp model that takes single phase input, and it's great, but not NEMA 4 rated. Precautions are necessary.

I think of the VFD as a power supply, and run a bank of machines from it. It is power, and does not overly care how much is being drawn at a time, up to its limit.
The best way would be to have a 3 phase breaker box, run a hot leg from the VFD to each bus bar, and select machines by the use of breakers.
Click to expand...

I am really new to this and learning like crazy. It is likely that 7hp vfd was not 1ph input. I know I need 1ph input.

"...not NEMA 4 rated. Precautions are necessary." What precautions do you take Salem? I see a lot more nema 1 vfd's and they are cheaper.

I have a buddy who is an electrician so he will do the wiring for me. But if I am reading this right, I can have the vfd output to a breaker box and then run to a 220v outlet and plug any 3 ph motor into it then? That would make it easy to hook up my lathe and get rid of the step pulleys I use now. I would just have to grab another motor from the guy I got these two from.

Randy
 
You could do it that way. With the breaker box though, I meant you could have a breaker for each machine, with the machines hardwired in or at least a plugged circuit to each. Switching plugs gets old fast if you have a bunch of motors off of the same VFD.

NEMA 4 is a dust proof enclosure, to put it simply. Optimum to protect your electronics in a knife shop. However, with NEMA 1 being way cheaper, you can build your own filter box, or at least wire the VFD up high and in a separate room from the grinders, then blow it out every now and then. That's what I do.

The breaker box for switching would only work if it's a 3phase box, expensive new but available sometimes used or surplus if you get lucky.
 
Actually one of the motors I bought came hardwired to a breaker box...so I have one done that way now by accident. I will have to take a closer look at the box and see what I have there. I just thought it was a pain when I was hauling it out of the trailer and to my truck...but I wasn't complaining when I had just picked up the motor or $30! Turns out the box was a bonus!

I like the idea of wiring up my lathe to a vfd too. Being able get the speed down really low opens up a lot more possibilities for turning. Putting the vfd before the switch box makes it so I just need one vfd for multiple machines. Never thought of that. I would have bought one for every machine!!! Not always the sharpest tool in the shed.

I think I will build my own enclosure. My electrician buddy has a junk pile of all sorts of stuff. I bet he would have a box I could start with for my enclosure.

I thought I had two baldors, but when I looked again one of them is a Canadian general electric. Still both run and solid.
 
Sounds like you are off to a good start, be sure to look around BF here to see what others have done for DIY dust boxes for VFDs. It is good to have a fan and a filter.
 
Okay...more questions about vfds. I see the odd one that is 110v single phase input and 220v 3ph output.

If I found one of these in 2hp would they work with my 2hp 3ph 220volt motors?

Here is the specs on a .5hp vfd with 110v input.

IP20 Optidrive E3 ODE-3-110023-1012
Input: 110-115V 1phase, 50/60 Hz 8 A
Output: 250V, 3 phase 0-500 Hz, 2.3 A
0.37 KW, 0.5 HP
 
Randy, It is pretty simple -
A .5HP VFD will run up to a .5HP motor
A 1HP VFD will run up to a 1HPmotor.
A 2HP VFD will run up to a 2HP motor
etc.
 
I may be misinterpreting the question, but I think what is being asked is whether a 110V single-phase in, 220V 3-phase out VFD of at least 2 HP rating would run his 2HP motor?

If so, the answer is yes, but I would not expect to find such a drive.

I'm over the pond and we don't really do the 110V thing over here, so the following is just surmise.

Because US domestic outlets seem to use mostly NEMA 5-15 outlets, I assume that you can use equipment rated up to 15A at 110V on your standard supply. That gives around 1650 VA, which would power a resistive load of 1650 Watts. A hair dryer for example.

When we start dealing with loads that have inductance or capacitance, we need to consider something called the Power Factor. We also have to account for any thermal and mechanical losses in the equipment. The net result is that the 1650 VA supplied by the 110V mains will, at best, power a motor producing 1 1/2 HP (1120W) of useful work after the power factor, VFD losses and motor losses.

I assume that once you need more than 1650 VA, you'll need to use a dedicated circuit. If you are running a dedicated circuit anyway, you might as well run one at 220V. At 220V, you eliminate the need for the step-up stage on the drive inlet, reducing the drive cost and removing a potential failure point. I would therefore expect there to be little or no demand for 110V VFDs rated above 1 1/2 HP. Without demand, there is unlikely to be a supply and I'd expect your chances of finding one to be remote.
 
Success! I got TWO 1ph 3hp 220v VFDs off craigslist for $88 each. I have been watching and snipe bidding on craigslist for a while now and the vfds that I want always go for about $180-240. Last night I tossed in a bid wound up winning at $88. The guy is moving a shop and he has a bunch of them so I grabbed a second one for my buddy at the same price.

My new question. I have two 3ph motors right now. I want to run one on my belt grinder and the second motor on my lathe. Salem got me thinking. Do I need 2 vfds....one for each machine? Or can I have it wired...
220v power to vfd
vfd to panel with lathe and grinder circuits
panel to the lathe and grinder

Then I would just turn on the circuit to the machine I want to use and control it with the single vfd. Would this be a reasonable idea? Or should I have a vfd specific to each machine? BTW I am working out of my garage!
 
That is what many people with one VFD and two or three 3Ph tools do.

Soon you will say, "Heck, I can change the motor on my drill press to a cheap 3/4HP motor and make it VS ... and my band saw ... and that old Sears 4" belt sander ... and every belt drive tool in the shop."
 
You can use a 3-pole changeover switch if you have 2 machines, but it gets a bit more complicated if you have more. It needs some way of ensuring you don't switch under power though. This can just be knowing what you are doing and being sure that anyone else using the shop does too.

I use plugs myself. I have a remote control box on a trailing lead that gets moved to whichever machine is plugged in and gives start, stop, speed control and fwd/Rev.

You need to see what others have done and work out which approach will work best for your own application.
 
I'm with Tim on this one - "IF" you "must" use multi motors with a single VFD, I'd go with plugs for sure. Easy, simple, and way to screw up.

"IF" you could get another VFD at the $88 price, I'd get another VFD (or 2.....3????) and have a VFD for each tool. that would allow moving grinder to different areas to work if desired.

Later
 
I used multiple plugs for a while. It gets old, especially when you have 8 machines off the same VFD.
The downside is not having controls at each machine. I solved that by building a remote control box on a cable leash that I can carry to whatever machine I'm using.
Wiring the VFD outputs to a panel, then a separate circuit with breaker/switch to each machine is the way to go IMO. You won't probably screw up and run two machines at once, or switch under load. You will have to make sure that no-one else does, though. If you teach anyone, watch them like a hawk.
 
The guy has quite a few of them. It says he is moving a shop. The VFD is a SAFTRONICS S10 AC DRIVE FM50-101-OC

Input 1 or 3 ph 200-240 volt 50/60hz 20 amp
Output 3 ph 0-240v 0-200hz 3hp 10.5 amp

I suppose at that price it would be a good idea to pick up another. It's about half of what I expected to pay.

Stacy, it was already going through my mind that I would like my drill press to be vfd driven and my 6x48" belt sander and I was mulling over the advantages of speed control on my band saw. I got pretty excited at the possibilities when it started to dawn on me that I might be able to have one vfd drive numerous machines.

Am I allowed to pass on this guys info if someone asks here or would I be breaking the selling rule somehow? I don't want to screw up.

Randy
 
Keep in mind, a bandsaw can be a bit more complicated. I not only have mine VFD controlled, but I had to install a jack shaft with a BIG speed reduction pulley to get my saw slow enough to work steel, even at 12 Hz frequency. My saw does have a 20" wheel though, so to get the motor to spin that slow enough for the SFM blade speed I wanted was difficult.
 
Salem Straub said:
Keep in mind, a bandsaw can be a bit more complicated. I not only have mine VFD controlled, but I had to install a jack shaft with a BIG speed reduction pulley to get my saw slow enough to work steel, even at 12 Hz frequency. My saw does have a 20" wheel though, so to get the motor to spin that slow enough for the SFM blade speed I wanted was difficult.
Click to expand...

Yes, I suppose I should start by getting the parts together and building my grinder, then convert the lathe. Maybe start looking at other things once I get those ones done. I tend to get going and come up with 4 new projects for every one I start.
 
Salem Straub said:
Generally VFD's can be had for quite large motors as well, and often they will work just fine for any motor of the HP rating or below. The KBAC 27 has a jumper that they recommend switching if using a lower HP motor, but I use my TECO FM50 interchangeably for several motors between 1 and 3 hp. I would say to research that about whatever particular VFD you may source.

For you, what will matter is phase conversion. Above 3hp it is uncommon to find VFD's that will take a single phase input. My TECO FM50-203-C is a 3hp model that takes single phase input, and it's great, but not NEMA 4 rated. Precautions are necessary.

I think of the VFD as a power supply, and run a bank of machines from it. It is power, and does not overly care how much is being drawn at a time, up to its limit.
The best way would be to have a 3 phase breaker box, run a hot leg from the VFD to each bus bar, and select machines by the use of breakers.
Click to expand...

Looking for a clever way to Nema proof the TECO FM50-203-C. I seen a guy use tuppaware with a filter vent
 
KUNTZI66 said:
Looking for a clever way to Nema proof the TECO FM50-203-C. I seen a guy use tuppaware with a filter vent
Click to expand...

I've been doing some browsing and looking at different people's diy dustproof enclosures in old threads. I need to find out how much ventilation and filtering is necessary because there is a lot of different ideas out there that range from zero venting to quite elaborate stuff.
 
You must log in or register to reply here.
Back
Top