Muriel,
I have a couple of questions and comments.
1. Is the video to the TV coming in via cable or antenna?
If you have a good cable coming in and you still get noise, it is more
likely that the noise is entering the chassis via the power cord.
{But, this is not ALWAYS the case as I've experienced when the cable
shield or grounds are not very good}. Putting the blender on the
other phase may help...but I 've never run into this situation and
tried something like you propose. Putting a powerline filter on the
TV is a way to see if EMI is coming in via the power cord.
If you have an antenna feed, the noise could also be radiated from the
long power feeds in your house. In this case, putting the blender on
a different phase will not likely solve the problem.
2. What does the interference pattern on the TV look like?
Are they in the form of vertical, horizontal, or diagonal bars that
roll across the screen?
Vertical or diagonal bars means that the source noise is greater than
the horizontal line-scanning frequency...in conventional TVs this is
15.75 kHz. If you have 10 such lines, your interference frequency is
is at 10 x 15.75 kHz = 157 kHz. This higher this frequency, the more
likely the energy is being radiated off the power line wires in the
wall of your home.
If the noise appears as two very narrow streaks separated by a 1/2
screen and that roll across your screen (as I suspect they would with
interference from brush type motors), your noise source is made up of
random pulses occuring at a rate of 60 Hz. This is broadband in
nature (has some high frequencies in it), so some of this could be
radiated from your home's power grid. Switching the blender to a
different phase will not help much in the case where an antenna is
used.
Dave Tarnowski
Whirlpool Corp.
St. Joseph, MI
Sounds like a definate "maybe".......
Mike Hopkins
> -----Original Message-----
> From: Muriel Bittencourt de Liz [SMTP:[email protected]]
> Sent: Wednesday, September 01, 1999 3:55 PM
> To: Lista de EMC da IEEE
> Subject: Doubt on household equipment interference
>
>
> Dear Members
>
> I'd like to solve a doubt.. suppose the following:
>
> "I have an electrical installation in a house. The feeding is with
> three-phase and one neutral conductors. If I connect a TV and a blender
> in the same phase, the blender generates interference (lines) in the TV
> screen. If I connect the TV in one phase, and the blender in another,
> the TV will have interference??? The neutral conductor is the same for
> all (of course!)"
>
> Seems very plain, but I'd like to know... :)
>
> Thanks in advance
>
> Muriel
>
>
> --
> ======================================================================
> Muriel Bittencourt de Liz
> GRUCAD - Conception & Analysis of Electromagnetic Devices Group
> Federal University of Santa Catarina
> PO Box: 476 ZIP: 88040-900 - Florianópolis - SC - BRAZIL
> Phone: +55.48.331.9649 - Fax: +55.48.234.3790
> e-mail: [email protected]
> ICQ#: 9089332
>
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