Re: [CAD_CAM_EDM_DRO] RF problem with VFD help

I think you need ferite cores on the motor side of the drive.

----- Original Message -----
From: "stan mcdonald" <SMCDONAL@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, May 14, 2002 6:51 PM
Subject: Re: [CAD_CAM_EDM_DRO] RF problem with VFD help


> OK I have tried the smaller capacitors as I had drawn and the 1uf and it
did not seem to make any difference. I next changed the carrier frequency
setting from 4 (10kzh) down to 1 which is aprox
> 2.5khz. This carrier freq reduction helpped by aprox 60 or so reduction in
RFI. Is there anything else that I can do to reduce this more?
>
> Thanks
> Stan
>
>
> Jon Elson wrote:
>
> > stan mcdonald wrote:
> >
> > > Hello list.
> > > I have an inverter 220 single phase 40 amps draw at full load, it
> > > generates alot of RF noise on the AM radios.
> > >
> > > To eliminate this noise problem seems to be more of a challange then I
> > > had hoped for but I have to eliminate this. I have installed a 1" pipe
> > > in the ground about four feet down and then removed a screw from the
> > > condute inspection cover from the hydro meter and ran a wire from the
> > > meter cover down to this grounding rod. This helps some. I also
grounded
> > > the machine to the breaker box since it is about 20 feet from the box
I
> > > took the liberty of using alot heavier wire then is required. I also
> > > installed the inverter in a steel NEMA box. I have two options that I
> > > know of left. Build a filter or use an isolation transformer.
> > >
> > > The transformer is expensive so I looked through some electronics
books
> > > and found a low pass filter which is suposed to pass 60 HZ
> > >
> > > 220 single phase in __________L1_____I___________ SINGLE PHASE OUT
> > > I
> > > I
> > > C1
> > > I
> > > I
> > > 220 single phase in __________L2______I____________SINGLE PHASE OUT
> > >
> > > C1=0.01 UF
> > > L1 & L2 1MH
> > >
> > > The capacitor is no problem but where can I get a coil that will pass
> > > the 40 amps?
> > > Is there a better way to eliminate this RF?
> >
> > You can make your own inductors. You may not need a lot of inductance.
> > If you can find some ferrite material, just winding insulated wire
around
> > it makes an inductor. Even without the ferrite core, just winding wire
into
> > a coil provides inductance, just not as much. Also, what you want is to
> > put the capacitors (need to be rated for line to ground service) from
line
> > to ground. .01 uF is pretty small. You may need as much as .1 uF of
> > capacitance, and may need to use 4 of them, 2 before the inductors, and
> > 2 after.
> >
> > I had the same problem (drove my computer controlled air compressor
> > wild, and also put fuzz on the video monitor on my CNC machine) but I
> > was only running 1 Hp on the mill, so I used a modest commercial line
filter
> > unit. I have seen some of these in larger sizes in such catalogs as
> > C&H, Herbach&Rademan, Surplus Center, etc.
> >
> > Jon
> >
> > Addresses:
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> >
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> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this as a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
>
>
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