Dave wrote:
Mark wrote:
modelman wrote:

Several months ago I had a high efficiency Trane XV90 natural gas
furnace and heat pump installed. Since the weather has recently been
cold enough for the gas furnace to provide heat, I have been
experiencing severe radio interference. The interference wipes out AM
broadcast reception throughout my house. I also see snow on a TV
connected to an external antenna.

The radio noise occurs as soon as the draft inducer motor starts up;
the pitch of the interference is related to the motor speed. The draft
inducer motor is a dc motor driven by a PWM controller on the main
circuit board. ... SNIPPED ...

DC motors are notorious noise generators. Those of us who used to be mobile when
6 VDC was the value of a car battery, and alternators did not exist, will attest
to the facts of generator [DC motor] noise.

A DC motor uses brushes to contact windings within the motor. As the motor turns
the brushes continually make and break current in the rotating armature
[inductance]. This making and breaking creates a very wide HF and lower VHF
noise spectrum. [Lots of sparks].

The solution, in the olden days, was a coaxial capacitor mounted directly to the
frame of the motor with the DC power running through the capacitor. I recall the
capacitor was about 1 inch in diameter and 2 inches long. Sprague made such a
critter.

Hope this history helps.

/s/ DD, W1MCE

I'm pretty sure these motors don't have brushes and are electronically
commutated and the electronics are causing the EMI...
Mark

Mark wrote:
Dave wrote:
Mark wrote:
modelman wrote:

Several months ago I had a high efficiency Trane XV90 natural gas
furnace and heat pump installed. Since the weather has recently been
cold enough for the gas furnace to provide heat, I have been
experiencing severe radio interference. The interference wipes out AM
broadcast reception throughout my house. I also see snow on a TV
connected to an external antenna.

The radio noise occurs as soon as the draft inducer motor starts up;
the pitch of the interference is related to the motor speed. The draft
inducer motor is a dc motor driven by a PWM controller on the main
circuit board. ... SNIPPED ...

DC motors are notorious noise generators. Those of us who used to be mobile when
6 VDC was the value of a car battery, and alternators did not exist, will attest
to the facts of generator [DC motor] noise.

A DC motor uses brushes to contact windings within the motor. As the motor turns
the brushes continually make and break current in the rotating armature
[inductance]. This making and breaking creates a very wide HF and lower VHF
noise spectrum. [Lots of sparks].

The solution, in the olden days, was a coaxial capacitor mounted directly to the
frame of the motor with the DC power running through the capacitor. I recall the
capacitor was about 1 inch in diameter and 2 inches long. Sprague made such a
critter.

Hope this history helps.

/s/ DD, W1MCE

I'm pretty sure these motors don't have brushes and are electronically
commutated and the electronics are causing the EMI...
Mark

Hi Mark, Modern HVAC, dishwashers, washing machines,ect. use variable
speed drives, which increases the efficiency of the devices. The
increased efficiency produces increased RFI due to the switching action
of the solid state devices (SCR's, BJT's, IGBJT's.ect). My washing
machine drives me crazy on Sat. morning on HF as my maid does the
weekly wash. As for what you can do? I don't know, it would require
vast amounts of filtering at the drives, I am sure that Trane and
other mfgrs are not willing invest in.

This is completely different from the usual thermostat interference,
and will be much more difficult to get rid of.
Gary N4AST

Mark wrote:
Dave wrote:
Mark wrote:
modelman wrote:

Several months ago I had a high efficiency Trane XV90 natural gas
furnace and heat pump installed. Since the weather has recently been
cold enough for the gas furnace to provide heat, I have been
experiencing severe radio interference. The interference wipes out AM
broadcast reception throughout my house. I also see snow on a TV
connected to an external antenna.

The radio noise occurs as soon as the draft inducer motor starts up;
the pitch of the interference is related to the motor speed. The draft
inducer motor is a dc motor driven by a PWM controller on the main
circuit board. ... SNIPPED ...

DC motors are notorious noise generators. Those of us who used to be mobile when
6 VDC was the value of a car battery, and alternators did not exist, will attest
to the facts of generator [DC motor] noise.

A DC motor uses brushes to contact windings within the motor. As the motor turns
the brushes continually make and break current in the rotating armature
[inductance]. This making and breaking creates a very wide HF and lower VHF
noise spectrum. [Lots of sparks].

The solution, in the olden days, was a coaxial capacitor mounted directly to the
frame of the motor with the DC power running through the capacitor. I recall the
capacitor was about 1 inch in diameter and 2 inches long. Sprague made such a
critter.

Hope this history helps.

/s/ DD, W1MCE

I'm pretty sure these motors don't have brushes and are electronically
commutated and the electronics are causing the EMI...
Mark

Hi Mark, Modern HVAC, dishwashers, washing machines,ect. use variable
speed drives, which increases the efficiency of the devices. The
increased efficiency produces increased RFI due to the switching action
of the solid state devices (SCR's, BJT's, IGBJT's.ect). My washing
machine drives me crazy on Sat. morning on HF as my maid does the
weekly wash. As for what you can do? I don't know, it would require
vast amounts of filtering at the drives, I am sure that Trane and
other mfgrs are not willing invest in.

This is completely different from the usual thermostat interference,
and will be much more difficult to get rid of.
Gary N4AST

Interesting discussion, folks....

As a controls engineer and High-Voltage electrician.... as well as
delving into HVAC control of late... here's my observations...

These manufacturers will always take the cheapest route possible and
damn the consequences. This is particularly true in power and control
systems.

A whole lot of manufacturers are moving toward PWM drives on their
blowers in particular. Many solutions are an 'on-board' frequency
chopper that is integral with the blower's motor.

These choppers are cheaply built and cheaply engineered. I suppose they
thought RFI and EMI would be insignificant due to the control being
mounted on the motor... but they're noisy as hell.

Suggestions: Replace the power cables with a shielded, VFD rated cable.
Belden makes a wide variety... I think they're called the VFD classic
line. Pay close attention the unit and cable grounding. Check to be
certain your house ground and neutral connections are only tied together
at the service entrance panel of your home.

My 2 cents...

Jake

"Jake" wrote in message
news:xB85h.54$xD.43@trndny08...
Interesting discussion, folks....

As a controls engineer and High-Voltage electrician.... as well as delving
into HVAC control of late... here's my observations...

These manufacturers will always take the cheapest route possible and damn
the consequences. This is particularly true in power and control systems.

A whole lot of manufacturers are moving toward PWM drives on their blowers
in particular. Many solutions are an 'on-board' frequency chopper that is
integral with the blower's motor.

These choppers are cheaply built and cheaply engineered. I suppose they
thought RFI and EMI would be insignificant due to the control being
mounted on the motor... but they're noisy as hell.

Suggestions: Replace the power cables with a shielded, VFD rated cable.
Belden makes a wide variety... I think they're called the VFD classic
line. Pay close attention the unit and cable grounding. Check to be
certain your house ground and neutral connections are only tied together
at the service entrance panel of your home.

My 2 cents...

Jake

As Jake said.... with the addition of....
Make sure that you have proper earth grounds for your power, and the HAM
rigs/shack. That will go a long way towards eliminating RFI. Make sure that
all the bonding screws in the furnace are clean and tight, make sure that
the furnace has a proper ground also.
When I put the shack together, I drove a seperate 8ft copper ground rod, and
silver brazed #6 solid copper to it, then silver brazed the wire to the
copper ground buss on the back of the bench. All equipment grounded.....no
problem.

de n6ojn

Motors with brushes are "incidental radiators" according to the FCC. I
believe PWM or variable frequency drive motors would be considered
"unintentional radiators" in that they intentionally generate a radio
frequency (9 kHz to 3,000,000MHz) but do not intend to radiate it. (see
definitions at http://www.hallikainen.com/FccRules/2007/15/3/).

Incidental radiators must use good engineering practice to minimize
interference (see http://www.hallikainen.com/FccRules/2007/15/13/).

Digital devices (I think motor control systems qualify as digital
devices) in appliances are exempt from the emission limits for
unintentional radiators (see
http://www.hallikainen.com/FccRules/2007/15/103/), though the user must
cease operation if the FCC finds it is causing interference.

wrote in message
ups.com...
Mark wrote:
Dave wrote:
Mark wrote:
modelman wrote:

Several months ago I had a high efficiency Trane XV90 natural gas
furnace and heat pump installed. Since the weather has recently been
cold enough for the gas furnace to provide heat, I have been
experiencing severe radio interference. The interference wipes out
AM
broadcast reception throughout my house. I also see snow on a TV
connected to an external antenna.

The radio noise occurs as soon as the draft inducer motor starts up;
the pitch of the interference is related to the motor speed. The
draft
inducer motor is a dc motor driven by a PWM controller on the main
circuit board. ... SNIPPED ...

DC motors are notorious noise generators. Those of us who used to be
mobile when
6 VDC was the value of a car battery, and alternators did not exist,
will attest
to the facts of generator [DC motor] noise.

A DC motor uses brushes to contact windings within the motor. As the
motor turns
the brushes continually make and break current in the rotating armature
[inductance]. This making and breaking creates a very wide HF and lower
VHF
noise spectrum. [Lots of sparks].

The solution, in the olden days, was a coaxial capacitor mounted
directly to the
frame of the motor with the DC power running through the capacitor. I
recall the
capacitor was about 1 inch in diameter and 2 inches long. Sprague made
such a
critter.

Hope this history helps.

/s/ DD, W1MCE

I'm pretty sure these motors don't have brushes and are electronically
commutated and the electronics are causing the EMI...
Mark

Hi Mark, Modern HVAC, dishwashers, washing machines,ect. use variable
speed drives, which increases the efficiency of the devices. The
increased efficiency produces increased RFI due to the switching action
of the solid state devices (SCR's, BJT's, IGBJT's.ect). My washing
machine drives me crazy on Sat. morning on HF as my maid does the
weekly wash. As for what you can do? I don't know, it would require
vast amounts of filtering at the drives, I am sure that Trane and
other mfgrs are not willing invest in.

This is completely different from the usual thermostat interference,
and will be much more difficult to get rid of.
Gary N4AST

Gentlemen Hi
and there is nothing that could be done to force OEMs
for clean up this interference (RFI?) That is nice but
you and I if interfere with some one TV in Neighborhood
FCC would be all over our ass thanks for equal justice
KA2AYS

AKS wrote:

SNIPPED


Gentlemen Hi
and there is nothing that could be done to force OEMs
for clean up this interference (RFI?) That is nice but
you and I if interfere with some one TV in Neighborhood
FCC would be all over our ass thanks for equal justice
KA2AYS



Not quite true!

I run 1KW on low bands [75 and 20 meters]. I have a tuner and low pass filters
in line. My station is properly grounded to the service panel ground/earth rod.
This connection is also the equipotential surface for the operating position.

My station meets ALL FCC requirements.

If a neighbor's tv, phone, stereo, or whatever, picks up my transmissions the
problem is with their equipment and I am NOT responsible for correcting the
situation. I will advise them regarding what needs to be done at their end and
at their expense. The best demonstration is to invite them into my station and
have them witness my tv, phone, stereo etc., being interference free.

The best demonstration is an RFI free home station.

We, hams, are not responsible for deficiencies in consumer electronics. That
rests with the manufacturer. The next time you buy a stereo read the Part 15
compliance statement!

Most likely it states, I paraphrase, this equipment MAY receive interfering
signals from near by transmitters. Buyer Beware!

/s/ DD

Mark wrote:
Dave wrote:
Mark wrote:
modelman wrote:

/s/ DD, W1MCE

Mark


Mark:

A quick check of the web turned up a site with posts dealing with the
same problem you are experiencing, it seems someone was able to make
some noticeable improvements in the rf interference generated--but not
totally eliminate... Just might be worth you time time to look, the
link I will paste is a long one, if it wraps you may have to copy and
paste both lines into the address bar of your browser and make sure
there have been no breaks, spaces, caused the whole link. Hope this
helps...

http://groups.google.com/group/alt.h...eb8ab594ac0781

Regards,
JS

"John Smith" wrote in message
...
Mark wrote:
Dave wrote:
Mark wrote:
modelman wrote:

/s/ DD, W1MCE

Mark


Mark:

A quick check of the web turned up a site with posts dealing with the
same problem you are experiencing, it seems someone was able to make
some noticeable improvements in the rf interference generated--but not
totally eliminate... Just might be worth you time time to look, the
link I will paste is a long one, if it wraps you may have to copy and
paste both lines into the address bar of your browser and make sure
there have been no breaks, spaces, caused the whole link. Hope this
helps...


http://groups.google.com/group/alt.h...eb8ab594ac0781

Regards,
JS


--Followed your link and was surprised to see that my comments, posted over
a year ago, are still floating around cyber space. Obviously apparent, that
the Trane RF noise problem hasn't been addressed by them. What is
disconcerting is that they have done nothing to minimize or alleviate the
problem and after more than a year are still producing furnaces with a known
RF noise generating inducer motor. Clearly a case of COST vs Customer
satisfaction---Charge more for the furnace, if that what it takes, and go
back to the motor that didn't have this problem. In my case, I had a
perfect back-to-back comparison--in the morning the first furnace worked
without incident--by noon, the new furnace was screwing up my (rabbit ears)
kitchen TV. I took a look at the new furnace and immediately saw that the
inducer motor was different--size and configuration. With a little bit of
experimentation, I finally narrowed the cause down to the inducer motor.
The installer had no clue, was very helpful and cooperative in interfacing
with Trane. Since I must have been early in the "new motor" time frame,
Trane shot-gunned the problem trying to eliminate it, ----new control board,
verifying electrical grounds, replacing the shielded motor harness (the
only thing that showed some signs of improvement). I guess at that point
they must have figured out that it was a bigger problem then they expected
and that's when the Trane Rep stopped returning my calls. It was easier to
run a cable line to the TV then to continue dealing with the installer, who
was shrugging his shoulders by this time, and the vanishing Trane Rep
MLD