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Anyone looking for a 7.5hp 3 phase VFD?


Active Member
I may have a line on 1 or 2 7.5 HP VFDs. AC Lenze SMVector series...I've used this brand before and they work good. Either use them @ full rating for 3 phase input or 4~5hp if you are inputting single phase.

Price would be about $350 in your hands(less than 1/2 price of new)...anyone interested?
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Active Member

Well...it IS somewhat of a big VFD but I also know some of our members have machines this size.
If I offered to buy both VFD's from guy they might drop to $300 ea but don't think I could get 'em cheaper.

If anyone else has a source you're welcome to toss it in this thread (besides the usual eBay/Kijiji options). I tried a local electrical surplus shop here in Calgary SE (I believe it was Civic Recycling) and they wanted $500 for something like this...clearly not a viable option.


Well-Known Member
Premium Member
I'm interested but have pretty good luck with chinesium vfds for less. (Haung yang)

The moons just don't align just now ....

Sent from my iPhone using Tapatalk


Active Member
I've always been spooked by Chicom vfd's: read a thread somewhere that some of the Chicom ones can put out dirty power/components fail prematurely and cook your windings...something I can't afford to do with a 58 yr old Morse pancake motor on my BP that I most likely cannot get rebuilt/replaced easily. It's just anecdotal evidence and someone would need to show me a series of tests on an oscilloscope to prove/disprove it but indeed, folks tend to stick with what works and I've personally had years of 'luck' with the AC Lenze SMVector's

Tom Kitta

Active Member
I had mixed feelings with the Chinese VFDs - they are cheap, they work... but one given up after just 6 months of use.

Both are now stored in a dusty corner as I moved onto just using a rotary converter & never looked back at VFD for phase conversion. As for using them to control speed I only miss it while facing on the lathe - most manual machines have fairly good speed selection (I don't have any belt based 3ph machines).


Active Member
Purest power would indeed be rotary-derived but my BP is a stepped pulley model; being an infrequent user I often find myself needing to change speeds mid-work to get it 'just right': fast enough to get the job done but slow enough to not get away on me. I've added a control console near operator position that has: on-the-fly forward/reverse segregated from main power(which used to be 6ft off the floor on the left side beside motor), jog, emergency shutoff, power indicator light and infinite speeds...turned that ancient iron into a much more usable machine and helps compensate for the 'memory loss' when I haven't touched the machine in a few months and I need to get re-acquainted with operations. Plus SMVector series has speed/torque compensation for lower rpm's and I do find that useful when I want to work slower but not stall the machine.

Tom Kitta

Active Member
Makes sense in your case - changing speeds with pulley setup would be a pain! My BP is infinite variable speed model so no issues there. My K&T #2 has the good old crank to change speeds - like 8 I think. Only a tiny mill I am planning to give to my dad has a pulley system - but its super fast to use it & its just 1ph.

I may use the VFD on a bandsaw to turn it from wood to metal - but the VFD doesn't actually have the range to do so to make it wood/ metal machine even with help of a reduction gearbox. The speed difference is simply way too great & VFD cannot also "speed up" the motor too much.

Tom Kitta

Active Member
The SFM have to drop even lower like 70 or so for stainless (and exotics but mostly SS). This can go up to 200+ for bi-metal blade.

The SFM on wood are 3000-4000 on garage size handsaws.

People create all sorts of strange arrangements - they have multi pulley setups etc.

VFD alone doesn't cut it as even with some pulley reduction - single stage - you are running on few hertz only - especially on large wheels like 20 inch diameter ones I have - this is easier on smaller bandsaw.

Also to bring the speed up you can go to like max 120 hertz - so just double on 1800rpm motor.

My current solution is to hunt for a 1:25 or 1:20 or 1:30 etc. worm gear reducer that can handle at least 1hp but preferably 3hp or so. Then I can use it for metal alone - to use it for *both* what is needed is a worm gear reducer and a two speed gear box - the worm is say 1:10 and the gear box either increases the speed by 5 times or decreases it by say 3 times - high and low. Fine tuning is with a belt.

I am just shamelessly coping design of actual wood metal vertical band saw.
Ok I've been trying to understand these vfd 's as they come in all colours and flavours .im looking to buy a mill this summer and have been looking now as I have seen here in Ontario the 3 phase mills seem to be a dime a dozen. So this Vfd you have a line on what size of motor are they for . Or better what amps if I run 220 single phase in what could I safely get out on 3 phase .


Active Member
HP specs at top of thread; VFD rated @ 23 amps which is typically good enough for 1ph 220v/5hp motor (and you'd rarely hit max power).

BTW - if mills are really that cheap out there, maybe toss the rest of us a few links with sales info...there is rarely a smoking deal on used mills in Calgary area since this isn't a manufacturing town.
Ok so most mills seem to be 1to 2 hp 3phase motors with this Vfd I can run 220 20 amp single phase in and be able to run the mill am I correct.


Active Member
if you're running as low as 1hp this would be overkill as you'd only be drawing 4~5 amps (depends on motor).

(Relatively) small mills are running 1-2 hp; many industrial units are running 3-7.5hp.
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Tom Kitta

Active Member
1hp is original BP - 2hp is the upgraded version.

You can actually start much bigger motors with that VFD - the 5hp limit is for max drawn power. So you could start 15hp motor (slowly) with it no issues - its load just cannot exceed 5hp.

For small motors - say 1hp 3ph you could start them very quick - no ramp up time with that VFD - one of the more annoying features of VFDs.

Note that VFD is for starting *one motor only* - i.e. if you have complicated machine with multiple motors you are not going to go for standard setup. Power feeds/ coolant etc. usually don't "upset" larger oversized VFD too much to be cause of concern.

If you have multiple machines you can use them all with 1 VFD - you just need to work on each machine one at a time & develop little plug for each. Note that this assumes that the 3ph machines are about same HP or you setup your VFD for the largest motor size or change specs each time.

VFDs are great if you need to use just one or two 3ph machines or are willing to do some playing with connect/ disconnect.

Rotary phase converters are IMHO more "professional" setup - you get true 3ph power in actual 3ph outlets... negatives are:
- you need to wire outlets - or all your machines need to cluster around the converter
- take up more space - hard to hide 10hp/ 15hp/ 20hp motor
- waste much more energy - 15hp motor heats up your garage with 400-500w - so around 1500BTU
- will not pass electrical inspection AFAIK (they are looking for a sticker on the control that says it is approved for Canada - if you build yourself you have to pay big $ for it)
- with all the setup take far more time and $
- you have 3ph just like if it was connected to your home without a meter (OK so you have one "wild leg" with 270V)

In case you are wondering unless you live somehow close to or in industrial zone (how?) you cannot get 3ph power - even if it is close to you the price to get true 3ph is in 10k+ range. Also the meter is extra every month. There are people whom had legacy 3ph and disconnected & use rotary.

Idiocy in North America is epic - on one hand they want to be green on the other hand waste is government sponsored. In Europe in most countries anyone whom wants 3ph at home gets it.