Thread: Fitting VFD to Craftsman Lathe

Here is a copy and paste of the email I have with DD about this (and a few other settings that maybe of interest). I see now that I didn't make clear in that email that we run 50Hz power here.
I have tried the fwd/rev switching but only with controlled stop. It ramps down just like normal then ramps up in rev as you would expect. Havent been game to try it in free run stop mode.

.Can the inverter be switched from FWD to REV without stopping first?(i.e. will it decelerate-stop-accelerate?)Can this also be done in "free run to stop" mode?

.Can I switch the coolant pump on after I have started the main motor?
or
.Can I switch the coolant pump on before turning the inverter output on so both motors start together?

F05 is set to 5 the manual says this is "high starting torque" for a 60Hz system. Is this a problem?
F18 is set to 70 the manual says it should be 100.

YES you can start the pump either way you mention but the second way is best as the pump will then be strted with the soft start,

You can switch form FWD to REV on the fly without a problem,

F05 will be best set at 4 for your application but 5 is OK if you use the speed control at low RPM,

The F18 parameter should be at 70 for a machine tool application such as a lathe or mill as the load is only applied AFTER the motor is up to speed, the setting of 100 would be used on an application where the load was on the motor from start up such as a car ramp for example and it will give the motor more starting amps to overcome the overload current without the inverter tripping,



Stuart

Hi Stuart,

I've got F1=2 and F2=2 2 seconds ramp up and 2 seconds ramp down.

The F18 parameter on mine I've set to 200%.... reading that email, maybe I've got that set a bit too high! might drop it down a bit..

Regards
Ray

I've just tried a few different things
F_05=1 + F_13=10 is still nasty
F_05=1 + F_13=5 takes about 9secs to get to 25Hz(on the way to 50Hz) and 15 seconds to get to 50Hz(on a 5 second ramp)
F_05=1 + F_13=0 3 seconds to 25Hz, 7 seconds to 50Hz
F_05=5 + F_13=0 as best I can tell it hits 50Hz in 5 seconds

I'll try playing around with the ramp speed. I never tried it short as I'm not normally in that much of a hurry

Stuart

You fellas are getting deep with the settings stuff, but that bit back there about high frequency whine ... on my set-up, which is a WEG 0.55kW 3PH connected to an ABB ACS350 (so not the same brands as yours), I get a bit of high-pitched hum from the motor when its running - I put it down to hum in the laminations - but might it be related instead to what you're saying about VFD settings?

Hi Stuart,

I think I know what's causing the chopping, if you try to boost the torque (by increasing the voltage on the V/F curve, either with F5 or F13) too much at low revs the output control in the VFD shuts off and then almost immediately comes back on, leading to the low frequency cycling, sounds terrible.

I have cycled through most of the F5 and F13 settings, and I get similar results whether I use the 50Hz curves or the 60 Hz curves, If I choose F5=2 and gradually increase F13 I can get to about 8% torque boost before it starts chopping.

So, I think the tentative conclusion, is that if you try to drive it too hard with torque boost it just starts chopping. Further, it will be different between my 240V system and motor, and your 415V system and motor, so whatever settings work for me, probably don't help you much, except to unravel what's going on with the various parameters.

And, despite what the manual says, I don't see much difference with the 50 Hz curves and the 60 Hz curves, but just to be consistent I'll stick with the 50Hz.

Hi Gunnadoit,

Have a look in your VFD manual and see if there is a parameter for setting the Carrier frequency, by default it's probably 8Khz which you might hear as a high pitched whine, try a higher carrier frequency setting, which just moves it out of the audible range. When the neighbourhood dogs start barking, you've gone too far...

Edit: In the ACS400 manual it is parameter 2605, might be the same parameter in the ACS350

Regards
Ray

Ray,
I've changed the ramp to 2 seconds which is working fine, I didnt get a chance to try F_05 settings again. maybe it wont sound as bad with a 2 second ramp?
Stuart

Cheers Ray, that's right about the "low noise" parameter on the ABB ACS 400; on my ACS 350 it is setting 2606. They don't call it "carrier frequency" but "low noise option". And in the In the ACS 350 manual they call it "switching frequency". For which the manual says:
"SWITCHING FREQ Defines the switching frequency of the drive. ... Higher switching frequency results in lower acoustic noise, but higher internal losses."
Also the accompanying graph shows that higher switching frequency results in higher drive temperature.

But guess what? If I increase the switching frequency from the default 8kHz to 12kHz THE WHINE STOPS!! Onya Ray. Ain't these vfds the dangdest thaings?

Because I already had taken the noisy cooling fan out of the drive (in consultation with the ABB techie, who said for home use I shouldn't need it), I'll monitor for extra heat (with my handy epidermic temperature sensor that I always carry with me).

Ray,
Changed F_05=1 this morning, that worked fine with a 2 second ramp. Then set F_13=10, chopping for a few seconds then OCA error.
I'll try a few lower ones.

Stuart

Hello Boys.,

I run my 2 horsepower mill motor via a 2.2kw Teco FM50. I use the mill's main power switch to turn the VFD on and off via a Sprecher and Schuh contactor. The motor switching utilizes the mill's extended lever switch which is connected to the VFD's remote switch terminals. All this works well. I do not use the variable speed facility on the VFD, prefering the mill's continuously variable speed control ( a single handwheel).

The mill is fitted with a 0.4 hp rapid table feed motor. This motor is controlled by means of a foot switch. My intention was to use another 0.75kw FM50 I have to run this motor.

Is there any way that two motors can be run both simultaneously AND ALSO independantly from a single VFD? The switching could be tricky.

Bob.

Bob, if I understand what you want to do correctly, then the short answer is no. It is possible to run two motors from the one VFD, I've never done it, but the manufacturers say the motors should preferably be the same. However they will simply do precisely the same thing, and I don't think that's what you want to do. You shouldn't switch motors in/out of an active VFD circuit.

From what you've said, if you want variable speed you'd need another VFD and 3 phase motor for the rapid traverse. However the VFD should be matched to the motor size. Unlike some fields, there is no advantage in putting, say, a large VFD driving a small motor and believing "more is better". They're not designed to work that way. With the Sews I use they have the option of selecting a motor size one frame size up or down from that the VFD is nominally designed for. That's it, and you shouldn't go beyond that limit if you expect the VFD to operate correctly.

Pete

BT.
If you wanted the spindle "on" or the spindle+powerfeed "on", its doable.(at least according to the guy at Drives Direct). But you can't have powerfeed only.
Stuart

Wouldn't the powerfeed motor need to be switched in/out of the VFD circuit with the spindle motor turning? If the powerfeed motor simply turns all the time with a mechanical clutch to engage it will probably work, even though they're not identical motors. On the other hand, there are a number of reasons why motors should never be switched out of an active VFD drive and there should never be any switching on the VFD output.

Pete

Pete,
Thats not what the guy from Direct Drives says. As long as you are only switching the small motor. The large motor needs to be switch with the VSD output.
Read his comments on post 47
Having said that I haven't tried it.
Stuart

I suspected that it would not work. The rapid feed would be used for table return and the spindle would most probably be stationary.

When I bought the 2.2kw FM50 I could have purchased a 1.5kw version for $40 less.
My youngest brother, an electronic engineer who does not work in the field of motor control, recommended the extra outlay just in case I chose to increase the mill's motor size. I run the Hercus 0.37 kw motor via the 0.75 kw FM50 with no ill effect.

On the Schaublin, I would be using the rapid feed motor at a fixed speed. I also have another 1/4 horse Westinghouse VFD to run the coolant pump which from memory is 0.1 of a horsepower.

Pete,

I just read your latest reply. The rapid feed motor is totally independant of the main motor.

The easiest thing is to wire up the .75 kw VFD to the contactor so that the mill's main power switch turns it on and then wire the foot switch to it's remote input terminals.

Is it detrimental to these devices to have them powered up but NOT driving a motor?

BT