# How to choose a VFD?



## toolman (Jan 17, 2014)

I haven't found any definitive answer to this, but I'm wanting to buy a VFD for my new mill. The motor tag shows 1.5/2.0 H.P. and 4.9/5.4 amps. Would it be ok to use a 2 H.P./7 amp VFD, or would there be any benefit to stepping up to a higher rated 4 H.P./10 amp unit?


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## Defens (Jan 17, 2014)

I'm in the same situation - looking to power a new mill I bought. I don't have a direct answer for you, but I have found that the companies I called were very helpful in directing you towards a suitable purchase. I think I called Drives Warehouse, Temco Industrial Power, and Wolf Automation. I didn't have all the info I needed yet to get their recommendations at the time - but they all would have been able to tell me exactly what to buy, and why.


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## CluelessNewB (Jan 17, 2014)

The amp rating is what is important.  The 7 amp should work fine.  Personally I would avoid the cheap Huanyang drives found on eBay.   A decent Teco or other well supported brand isn't much more money.  Even the screw terminals on the Huanyang drives are undersize and the screws are butter soft metal they are also electrically noisy.  I own one of them and 3 Teco's.  The 3 Tecos are an N3 a 7300 and an FM50.  I would NOT recommend the Teco FM50 for any machine that you plan to run at slower speed, it also has some limitations on using 3 wire control.  The N3 and 7300 are both nice sensorless vector drives.  I would also consider a Teco JNEV, basically the same as the N3 or 7300 without all the bells and whistles you probably don't need anyway for just a few dollars more than an FM50.


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## cdndewey (Jan 17, 2014)

I bought a Mitsubishi 220V single phase input, 220V three phase output, rated for 70 amps for my lathe, for $295 with taxes. I haven't got it hooked up yet as I'm still getting the wiring together and cleaning up the area where it will be mounted.

Here's a link to the unit if you want to have a peek....  http://www.allied-automation.com/pdf/D700_catalog.pdf


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## hvontres (Jan 18, 2014)

I am using a Hitachi WJ200-015SF with my 2Hp bridgeport. The motor is rated for 6A @ 220V. So far I am very happy with that setup. I really like the Jog feature, since I can power tap without having to switch grears and the spindle stops when I let go of the switch  The other nice thing is the soft start/electronic braking. I have a little writeup on my setup here : http://hvontres.blogspot.com/2013/08/brigepor-mill-for-garage-part-3.html

A few things to keep in mind:

1) You probably want to add a reactor to the output. This is a small inductor between the drive and the motor. That should help smooth out spikes in the output and help protect the motor from damage.
2) You probaly also want to add some filtering on the input. I don't know if I really needed it, but I added a single phase reactor and an EMI filter on mine so that the rest of the family would not get too annoyed when Daddy is playing, I mean working in the garage and the TV goes nuts.
3) You should plan on having some kind of enclosure for all of this. It helps keep out the chips and also keeps your fingers away from the high voltage stuff.

I got the drive new from a distributor on e-bay, the rest of the stuff came from automation direct.

Hope this helps,


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## miro (Jan 18, 2014)

_A few things to keep in mind:

1) You probably want to add a reactor to the output. This is a small inductor between the drive and the motor. That should help smooth out spikes in the output and help protect the motor from damage.
2) You probaly also want to add some filtering on the input. I don't know if I really needed it, but I added a single phase reactor and an EMI filter on mine so that the rest of the family would not get too annoyed when Daddy is playing, I mean working in the garage and the TV goes nuts.
_


I looked at the write up and on the circuit diagram, the reactor on the output is not legible ( my eyes don't work well anymore)
I have a similar VFD set - up  but I connect directly to the motor.
Can you please give some info about the reactor on the output? From the picture, it sort of looks like a ballast for florescent lighting.

More info on the input reactor and EMI filter would also be appreciated, even though my family doesn't get the TV interference, but my shop radio gets blitzed.
Thank you

miro


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## toolman (Jan 20, 2014)

Welp, I changed my mind when I found a smoking deal on a rotary phase convertor on fleabay. It appears to be a NOS Temco that ended up only being about $40 more than one of the cheap Huangyang (sp?) VFD's.


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## hvontres (Jan 20, 2014)

miro said:


> _A few things to keep in mind:
> 
> 1) You probably want to add a reactor to the output. This is a small inductor between the drive and the motor. That should help smooth out spikes in the output and help protect the motor from damage.
> 2) You probaly also want to add some filtering on the input. I don't know if I really needed it, but I added a single phase reactor and an EMI filter on mine so that the rest of the family would not get too annoyed when Daddy is playing, I mean working in the garage and the TV goes nuts.
> ...



Here are the automation direct Part numbers for the reactors:

*LR-22P0 *for the output
*LR-22P0-1PH* for the input.

The EMI filter is a Delta *VB30GS5* 

The main reason I put the output reactor in was to make sure nothing would happen to the motor. I priced a replacement motor for a J2 Bridgeport at ~$800, so I figured the $68 for the output reactor was worth it. As far as the input filter, I just didn't want to have to re-do all the wiring once i got the box working 

I hope this helps.


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