Variable frequency drive question

[ronan]

I've got a colchester master 2500 , i got it from my last job as it was too small for the work and was in the way, it has a dual voltage 220v/440v motor. I want to run it off a vfd at home as i hear they have better features then the old rotary converters, eg soft start etc , i have been offered a vfd but the output is 440v , is this ok ? Will it work ok if i leave the motor as it is in delta or whatever ?

Thanks.

 

[shenion]

Yes, leave it as it is. If it is 220/440 it most likely has dual windings. 230/415 would be delta/start setup.

Is the VFD input 230V? The smaller ones will step up to a higher output. Mine is 120V in, 220 out. Above about 1HP they require 220V in for 220V out.

The VFD needs to match the HP/KW of the motor. Mine is 1/2HP VFD and tried an 1HP motor. It tripped over-current in the VFD on startup.

My Atlas/Craftsman lathe has been completely transformed after changing to a VFD setup. Much smoother startup and a fast stop with dynamic breaking

 

[Wedg1e]

Nice tool!
I run a Boxford VSL500 from a 415V-out inverter (VFD) - fantastic. Mine's a 4HP I think, running a 2 or 3 HP motor. I normally leave it at 50Hz and just use the infinitely-adjustable belt pulleys of the VSL to change speed, but for extra control when screwcutting or if I'm using my mill (runs from the same VFD) I sometimes slow the frequency down for added flexibility

Does your motor run permanently in star configuration or is it switched delta/star? That may need some tinkering...

 

[ronan]

It is a dual voltage motor , i just wondered if i needed to know anything else about using a 440v out vfd, i knew a small bit about the 220v out type ,

Thanks

 

[graffian]

Is it a single phase input VFD?

 

[piman]

Hello Ronan,

I assume it was running 415v three phase at your works, if so all you need to do is connect up your 440 v VFR (Are you sure it's 440 v not 415 v?) However if the lathe has it's own inbuilt contactor, check the instruction book of the VFD as most must be connected directly to the motor, i.e you'll have to bypass the contactor and send the start signal to the VFD.

Alec

 

[hareng]

They do have contactors, several of them.
Now i did have a 5.5hp digital 240V input, 3ph 400V variable out to power a 3hp motor. Supposedly plug and play, lasted all of 1 1/4hrs £650 thank you goodbye. Current draw was around three times the 3hp on startup!

Had to have the 10hp well over a grand, so far so good but throws the RCCD one in every 2 to 8 startups.
Uses £1.23 of electric when putting a bit of a cut on.

Master 5hp motor? Clutch type easy to do or spindle start?
If want to run without faffing about and using all the existing controls, its gonna cost big time. Rating wise looking around 15hp! Plus you wont have soft start, all that does is soft start the contactors then motor requiring instant power, its what knackered mine above.

As above total rewire and run direct to motor. You would have to figure out the switching of any emergency stops, coolant, brake, spindle start switches 8 wires alone and lighting etc.
Meaning numerous separate runs to and from the inverter plus main 440V outputs. The chinese manuals mine 140 odd pages best of luck.
Could run direct to motor with soft start 3 secs but would then have to keep pressing run and stop on inverter, you will soon get pi..ed off.

 

[hareng]

i have been offered a vfd but the output is 440v

Should be able to vary the voltage, mines was preset 400V to run 415V.
Check what the inverters rated at.
Most can run 150% for X amount of time- seconds.

 

[ronan]

I was going to connect it directly to the motor and use the soft start , i have this lathe about 5 years and its just sat in my shed idle and i could really do with it for bike restorations i am doing, i did consider the rotary phase converter but was told they are inefficient. And also thought about fitting a single phase motor but was told the performance would be bad.

 

[Wedg1e]

It's not that hard to work out a control circuit to still incorporate all the safety interlocks etc., it's what I did on my Boxie. Essentially you link all the interlocks together in series and connect the inverter's 'Start' and 'Stop' buttons into it... so if it's already running and you open, say, a safety cover, it stops, or if it's stopped it won't start unless the safeties are satisfied etc.
My VSL also has the coolant pump connected to the VFD so that as long as the spindle's running you can have coolant - but if you slow the spindle down using the VFD, you also slow the coolant pump!
The only mod. I plan to do is fit a remote pot. to the VFD for up/down frequncy control: I don't do it often but when I do it's a pain to have to open the control panel and hold the buttons down.
You can also use the same VFD to run more than one machine (ideally not at the same time though!) - mine is configured using two contactors that are interlocked so that whichever is active prevents the other machine from starting.
Another issue is that the radiated field from the VFD can play hell with DRO's...

 

[ronan]

Can the vfd be wired so the original start/reverse lever can be used wedg1e ? It would be great to be able to use it for screwcutting , i am not that worried about anything else on the lathe working as the coolant pump can be run from a seperate socket as i think it is 220v and i don't really need a light.
A dro is a luxury i can't afford just at the moment.

 

[ford34/2]

inverter

I have 3 inverters running different machines, My last is a 71/2 Hp Speecon7200MA.

Now my harrison lathe is running 220/ 3 phase, I have a 3 way toggle switch fwd-stop-rev, and a potentionmeter for speed control, it will output about 100Cycles so the motor will run 2850 instead of 1425, Its handy but I still try and use the gearbox and gear selectors fitted to the lathe when convenient.
The harrison had a lever fwd/stop/rev I dissconnected this and all the original wiring, the inverter goes straight to the Motor.The switch and pot are in a small enclosure and its mounted on the lathe front. no complants at all and my other two systems work equally as well although are 415/3 phase.
mighy be worth a look at Drives direct site for a few more answers to your queeries, or even ringing Dave.-new number 01623720730/07976766538

 

[hareng]

The difference there though Ford is that lathe has a clutch being either an 11", 140 or an L5. I have one in single phase as well plus three others.

Wont get much help from Dave, you would have to figure the actual switching and other control circuits, tried it.

My rotary Transwave convertor is way more efficient than the digital, trouble is its that noisy cant even hear radio on very loud or phone ring.
Same machine run from rotary 7.5hp uses 35 p/hr spindle running. 10hp digital actually seen £1.20 odd register putting a little cut on. 3kw kettle as comparison registers around 30p/hr.

Ronan, how bigs the motor?
Is that Master with a clutch? If so dead easy.

 

[ronan]

The motor is 5 hp and the machine has a clutch .

 

[hareng]

Easy on then Ronan as Fordy has done.

Recheck the motor voltage 400V, 415V or 440V or even 480V.
Make sure the inverter is 240V input and 3ph min 5KW for above voltage wired soft start 3 secs direct to motor.

You need a bit more than the motor rating ie in the short space of time i got my 2.2KW motor running with a 3.75KW inverter, putting a minor cut on the spindle speed constantly dropped, i dont get it with the 7.5KW.

http://www.drivesdirect.co.uk/Downloads/InvertertoMotorWiring.pdf

Wish mine was that simple.

 

[Wedg1e]

Can the vfd be wired so the original start/reverse lever can be used wedg1e ? It would be great to be able to use it for screwcutting , i am not that worried about anything else on the lathe working as the coolant pump can be run from a seperate socket as i think it is 220v and i don't really need a light.
A dro is a luxury i can't afford just at the moment.

Yes, I retained the fwd/rev control. The only proviso really should be that you stop the spindle before switching because for a split-second as you change over, the VFD would see no load, which they apparently don't like.

 

[ronan]

If i were to go down the rotary converter route what size and type of motor would i need to run the 5hp motor ?

 

[hareng]

Rotary convertors are noisy at best.
I have a 7.5HP Transwave as back up, cant hear yourself think. Half tempted to get shut of it.

So 7.5HP min, though a 10HP better.
Advantage, no messing plug straight in to control panel same as my MA7200 inverter and about same price!

 

[Shox Dr]

I guess different RFCs make differing amounts of noise. I have a 7.5 (5kw) RFC and it's not very noisy at all.

 

[ronan]

I didn't get the inverter i was after , it was sold again i could get to it , anyway there is a 5.5 hp omron inverter on ebay being sold by kaylo uk , would this drive the 5hp motor of the colchester well ? 5.5 hp seems to be as big as they get in single phase.