RFI filter/Powermatic 3520

Re: RFI filter/Powermatic 3520

Michael Stadulis, in Gloucester County, NJ

>I believe that someone else here used the Oneway RFI filter successfuully on a 3520A.

Mike

Re: RFI filter/Powermatic 3520

Doug

>Mike I can find no evidence that anyone has put the filter on a PM 3520A. A while back Mark Kauder wrote about successfully installing one on a Vega 2400. However, I think that is on a single phase motor which only has two wires plus the ground. On the PM the three phase motor has three wires plus the ground. I am not real confident that I am correct in all this - maybe someone could straighten me out. I would sure like to know how to stop the static. My lathe is in a daylight basement and the static is strong throughout the entire house - not sure about neighbors. No static on FM radio.

Doug

Re: RFI filter/Powermatic 3520

Bill Howatt

>That's the way the inverter-based variable-speed drives work including Oneway's.

The filter doesn't go between the inverter and the motor it goes on the input power line supplying the converter.

I haven't use one of these but it goes between your 240V line and the lathe electronics. Be sure you get the line side of the filter to the line and the load side to the load (inverter) and ensure you connect the ground.

RFI typically radiates both from the inverter components directly and from high-frequency signals sent back out the power-line which then uses all the wire in your house as an antenna. The RFI filter blocks the latter source. The AM radio band is the most affected because it is much closer in frequency to the signals being radiated. The lowest TV channel is about 50 times further away than AM radio. FM radio is about 90 times further away.

Bill

Re: RFI filter/Powermatic 3520

Mark Kauder. Phenix City, AL

>Doug,

First let me say that I am no expert, but from what I know, Bill is right.

I installed my filter between the wall and the electronics of the inverter/controller. If your wiring is like mine, the 220v coming into the shop is 4 wire; two power (one for each phase,i.e. power leg in your breaker box) which can be white, black or red (any two colors), one green ground, and a bare copper ground. In my case, the two power wires coming into the shop were black and red, while the two power wires in the lathe's powercord were black and white, while ground was green. As described in my review in the W.C. articles section, I left the ground wire un-cut - severed the white and black and attached the RFI Filter in between the severed ends.

Works just great. I have since notice that when the controller/inverter is turned in a certain direction, there is some interference, but not nearly what it was before.

Mark

Re: RFI filter/Powermatic 3520

Dick Hines

>I solved the HF proublem after I got my Pm 3520 a few years ago. I just tune to FM stations or pt on a CD. Have had no Hf proublems since.

Re: RFI filter/Powermatic 3520

Mike Swain

>Hello Doug,

Having watched the posts regarding the radio interference caused by the PM3520 I asked around in the UK, I was given a Schaffner FN2060 filter to test out.

I was given many ways of fitting it but it would appear that using Bill's method is the correct one, simply fitting it into the cable from the mains. We have three core 240v electics overhere.

To me this seemed too simple but I've had the same information from at least three reputable filter manufacturers. I have not got round to trying it yet but will in the next few days.

Regards....Mike

www.creative-woodturning.com

Re: RFI filter/Powermatic 3520

Richard Allen

>Hi Doug

Contact Keith athe Oneway. He can help answer your concerns. He will very likely take back the filter if you haven't used it and are unhappy with it.

Good Luck

Thanks for info

Doug

>Thanks to all for straightening me out. Unfortunately the filter (when installed correctly ahead of the controller) did nothing to stop the static. SWMBO will have to listen to FM :)

Few things to consider

Bill Howatt

>Sorry you didn't have better luck since based on other experience it sounded like the solution.

Try the following with your battery radio first since it will eliminate any interference coming into its power supply via the powerline. Try different radios also.

Can you move the radio further away from the lathe since the intensity will diminish with distance?

Have you tried turning the radio to various different angles relative to the location of the lathe? Radio antennas are often directional and you may be able to minimize the interference. Pick up the radio and turn/tilt it to see what happens.

Are all the metal panels (if any) back on the lathe. Without metal shielding any signals radiated by the inverter itself will still get out.

Is the filter unit inside a metal box such that the line cord is the only unfiltered piece of wire coming out of the lathe?

Bill

Re: RFI filter/Powermatic 3520

walta100

>Are the wires from the inverter to the motor shielded? Is there a sheath of grounded braided wire surrounding each of the conductors that power the motor?

interesting results

Doug

>Some interesting results. With battery radio had to go outside and at least 50 feet from house before radio cleared of static. At least the neighbors are ok.

More interesting I found that with power on to the controller and the lathe off (motor not running) the controller emitted a small but noticeable amount of static. More intense close to controller but also detectable from anywhere in the house. I didn't test this from outside the house.

I even put the exposed lathe wires into flex metal tubing. I don't have any idea how I could shield the controller which seems to me to be the culprit.

Such is life.

Doug

wire shielding

Doug

>I did put the lead from inverter to motor inside a metal flex conduit.

The wiring came with the lathe. I don't think any of it is sheathed in grounded braided wire. Maybe that should be my next attempt before I completely give up.

See "Interesting results" above.

Thanks for advise,

Doug

Re: interesting results

Bill Howatt

>Hi Doug,

You will get some interference with the controller on but no motor activity since the electronics are running but aren't switching much current. Radio waves are moving electrical charges (current) so the more current the more interference all other things being equal.

Are you saying the controller itself is not shielded by a metal box? My General has the Square-D controller mounted inside a steel box with a hinged lid on it. If it isn't, you could try making a temporary one out a cardboard box covered with aluminum foil (which is grounded) and see if that helps.

Has this problem been discussed with the lathe manufacturer by anybody?

Bill

Re: interesting results

Doug

>Hi Bill,

My controller is incased in what appears to be plastic with an aluminum heat-sink attached to back.

As to the manufacturer (PM)- I have been unable to contact anyone who could or would address the problem.

Doug

Throw some muscle at 'em...

Rod Peterson -- Ormond Beach

>The device is almost assuredly a Part 15 device with regards to RFI which has no spectrum protection as a user whatsoever. However, the manufacturers of Part 15 devices are responsible for assuring the emissions of the device are at permissible levels and cause no interference for users of spectrum that is protected (such as the AM and FM broadcast bands).

What does that mean? When you finally do get someone at PM, tell them that you have complaints of RFI from your (their) controller and you want them to fix it. They are required to by the FCC rules, although they may try and stonewall you and say it's a fact of life. It isn't. And they must.

Rod

Re: RFI filter/Powermatic 3520

walta100

>Seem to me that any variable frequency drive that is not mounted in a grounded steel box is going to generate unacceptable radio interference. Are the older PM 3523A logic in a plastic housing?