Thread: Lathe VFD conversion-Pope motor and VP600 VFD

Originally Posted by redlaci2004

Hi All
I have a Woodfast wood lathe that I would like t convert to a 3 phase unit controlled by a VFD. I have a number of questions:

The lathe is fitted with a 0.75 kW (1hp) single phase motor running at 1400rpm.
Should I just replace the motor for the equivalent power or should I go larger to 1.5hp?

Yes, and I would even consider a 2HP motor.

Should I also go to the 2800rpm version, thinking not as I want to use lower speeds where necessary, but with some belt change this might not be an issue?

A (50Hz) 1400 rpm motor can usually be operated from 20Hz to 120 Hz ie 20/50 x 1400 = 560 rpm to 120/50 x 1400 =3360 rpm for a 6:1 speed change
A 2800 can be operated from 20Hz but should not be operate above about 75 Hz (4500 rpm) as the bearings and rotor are usually not designed to go that fast. This gives a speed change ratio of about 3.75:1

In other words, provided you select a suitable operating belt position) you have a wider speed range to play with when using a 1400 rpm motor.

Originally Posted by BobL

Yes, and I would even consider a 2HP motor.

I agree with Bob. In my experience a 1.5HP lathe will be challenged at times by more demanding tasks like coring. A 2HP motor will give you the additional power needed to do everything you are likely to demand of it. For me the additional cost of a 2HP/VFD conversion would be well worth it.

Thanks BobL and Neil.
For what I do I have decided to go with a 1.5kW motor as the 0.75 I have now has never been an issue so 1.5 with a VFD should be well worth the investment.
On a second question, the Pope VFD states an input current on 14A and output of 7A. I assume that all the electrical connections ie fuses, contactor and overload need to be matched to the 14A rating? Sorry if this is a dumb question, but always better to check.
Thanks and Merry Christmas to all
Red

Originally Posted by redlaci2004

Thanks BobL and Neil.
For what I do I have decided to go with a 1.5kW motor as the 0.75 I have now has never been an issue so 1.5 with a VFD should be well worth the investment.
On a second question, the Pope VFD states an input current on 14A and output of 7A. I assume that all the electrical connections ie fuses, contactor and overload need to be matched to the 14A rating? Sorry if this is a dumb question, but always better to check.

There must be NO switches or contractor or fuses between the VFD and the motor. The VFD takes over all these functions.
A mains switch between the GPO and the VFD can be used or you can use the GPO switch.
A mains switch between the GPO and the VFD can also be used as an E-switch.
Switching the lathe on-off is done by the start/stop switch on th VFD or a remote switch linked back to the VFD - check the manual.

Sorry about the dumb question, I know little about electrics.
Can any lathe motor be fitted with a VFD device?. And should any electrician worth his salt be able to do the job?.

Originally Posted by artful bodger

Sorry about the dumb question, I know little about electrics.

No problems

Can any lathe motor be fitted with a VFD device?.

No. The motor has to be 3P and capable of being converted to run under 240V 3P.
The VFD converted 240V single phase to 240V 3P so allow the motor to run

Most small 415V 3P motors are connected/wired in what is known as a STAR (Y) connect.
When these are converted to what is known as a DELTA (∆) connect that automatically converts them to 240V 3P capable.

Sometimes this can be done in the motor connection box, other times the motor has to be taken to a motor rewinder to have the motor opened up and converted. I have heard this can cost anywhere from a couple of cartons to $150+

And should any electrician worth his salt be able to do the job?.

Not all general electricians are up for this.
I would specifically ask the sparky "can you install a VFD" - if they ask "What's that?" then look elsewhere.

If you have time read this thread to find out more.
VFD install summaries

PopeWiring.pngOK, that's odd, since the manual (install page attached) clearly shows the need for a fuse, circuit breaker and EMI filters?
The other question is what effect would adding these have to the motor?
I will be running the start/stop and speed remotely, that is fine, but providing the power to the unit is what my previous question was referring to.
Thanks

Originally Posted by redlaci2004

PopeWiring.pngOK, that's odd, since the manual (install page attached) clearly shows the need for a fuse, circuit breaker and EMI filters?

That circuit diagram shows these before the VFD - not after.
The 240V GPO should already be on a fuse/breaker.
Filters are not normally needed for a single small motor.

The other question is what effect would adding these have to the motor?

They may damage or destroy the VFD

I will be running the start/stop and speed remotely, that is fine, but providing the power to the unit is what my previous question was referring to.

OK, these were always going before the VFD not after.
If the GPO is on a fuse breaker already, how can adding one damage or destroy the VFD?
Also, if this is the case why are they instructed to be added by the manufacturer?

Originally Posted by redlaci2004

OK, these were always going before the VFD not after.
If the GPO is on a fuse breaker already, how can adding one damage or destroy the VFD?
Also, if this is the case why are they instructed to be added by the manufacturer?

Sorry - we're getting our wires crossed here. I'm talking about having a fuse/breaker between in the VFD and the motor.

For small (2HP or less) motors, if the VFD is connected to a correctly wired 10A GPO an EMI filter and/or extra fuse/breaker is not needed.