# 110vac Vfd



## jbolt (May 11, 2015)

I'm looking for a spindle/VFD for my smallish router project. I only have one 220v circuit in the garage which is shared between my lathe, mill and air compressor (not used simultaneously). I also have two dedicated 110vac circuits. It would be ideal to be able to use the router on 110v so the lathe or mill could be used at the same time.

Automation Technologies lists a 110v 1.5 kw VFD/spindle package but I am skeptical. 

From what I have read it was my understanding that 110v VFD's were usually limited to 1hp or less? Our lathe at the school is supposedly rated at 1.5hp and being driven by a Delta VFD at 110v?

Wondering if anyone has any experience with this?

Thanks,

Jay


----------



## JimDawson (May 11, 2015)

I think that the reason the 120V units are generally limited to 1 HP is the current draw.  A standard 15 amp, 120 volt outlet would run a 1.5 KW motor, but not a lot, if any, left over.  A 20 amp, 120 volt circuit would leave some margin.  There is no physical reason that a 1.5 KW motor/inverter couldn't be built to run on 120 volts

I have one installation that runs  two  5HP motors on 120 volts, single phase, about 50 amps each.  Why they did it that way I have no idea.


----------



## jbolt (May 11, 2015)

Thanks Jim,

Both my 110v circuits are 20A. I was not concerned about the current draw but more about how well the VFD performes on 110v. If it is as they claim maybe I have nothing to be concerned about other than it being a Chinese spindle/VFD.

Jay


----------



## JimDawson (May 11, 2015)

jbolt said:


> If it is as they claim maybe I have nothing to be concerned about other than it being a Chinese spindle/VFD.



Yeah, there is that


----------



## mksj (May 12, 2015)

Just a general comment on circuit breaker capacity vs. safe capacity of a branch circuit (outlets). A 20 amp circuit is not rated at that capacity for a sustained time period, the NEC specifies the safe capacity as being derated by 20%. So a 20A circuit has a safe load carrying capacity of 1920 Watts, and a 15A circuit as 1440 Watts. Wiring length if long, would further derate the load carrying capacity. If the motor can actually deliver 1500 Watts (full 2 Hp) and one factors  efficiencies/power factor to generate 1500 Watts, you could be pushing a 20A circuit, and could not use on a 15A circuit. The main concern would be sustained maximum output of the VFD/motor, which is unlikely in a home hobbyist situation. The rated current for a 1Hp VFD running at 115V is something like 16A (GS2 11P0) which would require at least a 20A breaker. This is most likely the reason why 1 Hp (750W) is the usual maximum size of VFD offered at 120V by most manufacturers . If you look at motor sizes for equipment for 20A 120V circuits, the maximum size is usually around 1.5Hp, although many manufacture may state a higher peak horsepower to make you believe their product is better.

In this case, you are probably OK, often the rated capacity for non-industrial setting is a bit overrated relative to the actual true value (like Hp). I would not plan on any sustained full output use.  I see no reason why the VFD could not deliver 1500W off of 120V line, but in reality it should be on a minimum of a 30A breaker and 10G branch circuit wiring. A 2 Hp VFD at 220V usually specifies a 30-35A breaker.


----------



## jbolt (May 12, 2015)

Thanks for the info mkjs.

You got me thinking. I have a Porter Cable 3-1/4 hp wood router, which is a beast of a hand held router, that is rated at 15 amps. Makes me wonder how the math works for that one?


----------



## jbolt (Jul 5, 2016)

Just wanted to update this thread. 

I ended up purchasing the KL-VFD15 1.5kw (110vac) VFD & water cooled spindle from Automation Technologies and have been running it on my CNC router for about a year. I can't say what the actual output power is but as far as performance goes I have not had any issues on the 20 amp circuit which runs the vfd/spindle & 34 size steppers/gecko drives/80vdc PS.

As for the performance of the VFD & spindle, I've cut hardwood, MDF, plastics, aluminum sheet and this past weekend I did a 1' x 14" cut-out on a 0.09" steel back plate for an electrical enclosure taking 0.01"cuts at 5 ipm with a 0.125" 4 flute carbide end mill. The spindle never gets hot or bogs down. Cooling is done with a PC water cooling radiator, 100mm 12v pc fan and a 10% solution of antifreeze. 

My work area is only 18" x 24" and my tooling has been 1/4" or less except for a 1" rabbit bit I use for facing. 

So far I am very pleased with the spindle/VFD combo.


----------



## den-den (Jul 5, 2016)

jbolt said:


> Thanks for the info mkjs.
> 
> You got me thinking. I have a Porter Cable 3-1/4 hp wood router, which is a beast of a hand held router, that is rated at 15 amps. Makes me wonder how the math works for that one?



The math does NOT work for that one.  As my grandfather often said "figures don't lie but liars will figure".


----------



## ARKnack (Jul 5, 2016)

jbolt said:


> Thanks for the info mkjs.
> 
> You got me thinking. I have a Porter Cable 3-1/4 hp wood router, which is a beast of a hand held router, that is rated at 15 amps. Makes me wonder how the math works for that one?



It's called specsmanship.  that means bending the laws of physics to suit your need of a sale.. the hp rating of those small motors like routers, vacuums, etc are rate as peak hp. in other words that is how much power the motor will generate JUST before the magic smoke is released. 

on the 115v VFD one word of caution. Don't try to run it on a gfci protected circuit. It will most likely trip the gfci. I tried mine on 115v and all it did was trip it. I had to change it over to 220v non gfci circuit.  The vfd was not a cheap Chinese unit either.


----------



## hvontres (Jul 5, 2016)

jbolt said:


> Thanks for the info mkjs.
> 
> You got me thinking. I have a Porter Cable 3-1/4 hp wood router, which is a beast of a hand held router, that is rated at 15 amps. Makes me wonder how the math works for that one?


Well, I think the main thing to remember here is that your router is running at 20,000 RPM, while most induction motors run at either 1800 or 3600 (nominal). Here is the formula for Horse Power:


In electric motors, Current draw is roughly proportional to Torque, not power. So an easy way to get more horsepower from the same amount of current is to just spin the motor much faster. Of course, unless you are spinning a cutter at insane speeds, you then need some kind of gear reduction to get any sort of useful work done (think of an angle grinder or a skill saw).  Here is a wikipedia article the explanins this more in depth: https://en.wikipedia.org/wiki/Horsepower#Calculating_power


----------

