Fan causing MW RFI (2023 Update)

I have a 6-months old Fantasia ceiling fan (mains powered, with 6-speed reversible dc motor) which is causing a lot of interference on MW. FM is not affected. The interference is there on forward or reverse rotation, worsens as the speed is increased,, and appears on portable as well as mains-powered radios.

I can return it to the supplier for replacement or refund, but it is a bit of a rigmarole to remove and refit. All the electronics are sealed in, and the only accessible wiring is to the mains connector. Is there any point in trying some sort of screening or RFI suppression on the mains wiring before I take it down?

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Jeff
Reply to
Jeff Layman
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I find it amazing you can listen to MW/AM in a "modern" house with all that electronic smog and EMI and RFI everywhere

Reply to
N_Cook

Just about everything has a SMPS these days, and often some digital control. Can't say that I've ever had a problem with any of these before.

Anyway, is there a more nostalgic way to listen to 60s hits than on a MW portable with a tiny speaker?!

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Jeff
Reply to
Jeff Layman

How about one of these for nostalgia and low-fi

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I repaired one a year or more ago, the owner is supposed to be in the UK and collecting it later this week. Pioneer must be embarassed , its first domestic product. Hardboard deck and no electonics , relied on the old telephone carbon granules principle to feed a speaker, seriously tinny and tiny

Reply to
N_Cook

I find most switching supplies sound through MW and LW only when the radio is one meter or less near. Further than that they have little effect.

Reply to
Jeroni Paul

I would certainly try a noise filter at the mains connection. This would block conducted EMI pretty effectively, which is likely the path through which the noise is getting out of the fan unit.

Corcom (TE Connectivity) and other companies make modular filter "cans" which might help a lot. They have various combinations of shunt C, and series L (wired up for common-mode and differential-mode suppression), with different amperage ratings and different sorts of termination.

A Corcom model 3VW1 might be the sort of thing you're looking for... 3 ampere limit (up to 250 VAC), has both common-mode and differential- mode inductive filters, "effective to control emissions in equipment using SCR and TTL circuits for compliance with FCC Part 15, Subpart J and EN55022, Level A, down to 150 kHz."

This "can" model has .25"/6.3mm spade-lug terminals for the line and load side... Corcom does make some which have wire-lead terminals but none in the W series, unfortunately.

If the fan is hard-wired to the mains (you didn't say) then installing a module of this sort in the junction box would be the way to go. If it's a plug-in to a mains outlet, then you'd need to build some sort of goes-in-between box or a "filtering jumper cable".

There are quite a few other manufacturers of similar sealed EMI filter modules... Corcom is just the best-known-to-me.

These sorts of filters are commonly available through surplus channels (online dealers, ham-radio flea-market sales, etc.) as well as through distributors such as Mouser and Digi-Key.

Reply to
David Platt

You might try winding the AC lines through a ferrite RFI core like the ones found on switching power modules. Some can be clamped around the wires. You will want to get all three leads through the core, L, N, and Ground. Maybe even do a couple of turns if the core is large enough.

Reply to
Tom Miller

** The instructions say all units must be earthed - is yours?

You could try a suppression cap across the line( active to neutral) at the terminal block - close as possible to the fan itself. A class X1 or X2 film cap of about 470nF is a good place to start. But I bet there is one inside the fan already.

I expect the fan motor is a BLDC type, possibly operating at mains voltage, and the pitch of the noise on AM would vary with its speed.

BTW:

Are you living far from AM transmission sites - say than 50 kms ??

BTW 2:

Are you living in a metal clad ( aluminium sided ) building ?

Either of the above means the AM signals inside your home will be very weak.

.... Phil

Reply to
Phil Allison

Does the interference show up when you use a battery operated radio? That will give you some idea as to whether the interference is conducted or radiated, or, maybe both.

Reply to
hrhofmann

** Try reading the OP.
** Huh?

Conducted interference ends up radiating via the AC supply wiring.

... Phil

Reply to
Phil Allison

My furnace fan creates so much noise, I can't do much with it on. It's variable speed, and has peak noise at max speed. I tried some filtering on ac and thermostat, but it's a big problem.

Greg

Reply to
gregz

I hope so! It was installed by a pro electrician and I have a NICEIC certificate which says so

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But I'll check it anyway.

The only thing I can get in the next day or so is this delta suppression filter:

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Guess so. The fan often turns in the reverse direction for a second or so when switched on, then corrects itself.

No. The 999kHz local radio transmitter (1kW) is about 15 km away..

The fan is in a new metal-framed conservatory. The mains-powered MW receiver in the conservatory is completely swamped by the interference. But the portable radio is outside, maybe 6 metres from the fan, and that has the interference superimposed on the station I am listening to. It's no doubt attenuating the interference, but not enough

Thanks for the info and suggestions.

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Jeff
Reply to
Jeff Layman

I'll try that. Thanks.

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Jeff
Reply to
Jeff Layman

** That should do OK.
** Really ?

What makes you sure it is a DC motor ?

DBDC motors are really AC motors with in-built electronic drives.

Motors that power ceiling fans are normally multi-pole induction types - fully reversible.

** So the available signal is weak.
** So the signal inside is very weak.

... Phil

Reply to
Phil Allison

See under "Energy efficiency" on page 3 here:

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Also see top of page 2 and section 3 on page 10 here:

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So it could be that the manufacturer calling it a "DC motor" is being a bit flexible with the definition?

Fairly so, but reception is quite acceptable when the fan is off.

Indeed, even with a loop aerial connected.

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Jeff
Reply to
Jeff Layman

** So my original hunch was correct.

Some modern ceiling fans use low voltage( ie 24V) BLDC motors operating from a SMPS - all crammed into the same housing. Why one would run in the wrong direction before correcting itself is a tad mysterious.

** You have missed the point.
** Assuming the fan has not developed a fault since you installed it, the RFI you are hearing may well be within legal limits for such appliances.

The AM and HF (short wave) bands do not enjoy the same regulatory protection as FM and TV reception does - so things like SMPSs and motor drives are permitted interfere somewhat with AM receivers in the same premises.

Having only weak signals available in the vicinity makes it so much worse.

Is the fan motor in a plastic enclosure ?

A grounded, metal one would be far better at supressing AM band noise.

.... Phil

Reply to
Phil Allison

Puzzled me too so I Googled for the explanation. I have no idea if it is accurate, but see the final paragraph in this section:

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I don't know if it is. It should fall within Directive 2004/108/EC, but it isn't CE marked, and compliance with that Directive isn't mentioned in the manual.

I think it is plastic.

Anyway, I was able to try a few things today, and the interference has been reduced to almost zero. Firstly, the earth appears OK. Just in case, I connected another earth lead to a known good earth, but it made no difference. Next I fitted the delta filter, which suppressed the interference almost completely - result! Next I pulled the power connector plug apart and wound the lead a couple of times through a large ferrite ring (the only one I could get easily), and that cut out almost completely what little noise was left. There is slight interference when the fan is running at full speed, but I never use it at that. speed.

So that's a good result without dismantling and returning the fan - thanks.

But here's something odd I found on the way. I got the MW on the mains-wired radio in the conservatory working pretty well with only a metre of wire connected as an aerial. It wasn't bad, but a bit quiet. Well, the signal was weak. Fair enough in the metal conservatory. But that was with the fan power connector unplugged (for fitting the ferrite ring). As soon as put the power connector back together, so I could run the fan (this is with the main power still disconnected at the wall switch), the radio reception improved tremendously - loud and clear! When I pulled the connector it went back to fairly quiet again. Weird - something is acting as an aerial, but how?

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Jeff
Reply to
Jeff Layman

The nerve of them to put Hawaii on the box, after what they did to Pearl Harbor!

Reply to
junebug1701

Fantasia ceiling fan (mains powered, with 6-speed

try a few turns on a fairite core on the power leads at the device type 75 are only about a $1 , I put them on everything in my home ko6kL.... more on my qrz.com page.

Reply to
johnsonsatake

Looks like Google Groups is doing funny things again. Your reply is to a post I made over 5 years ago!

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Jeff
Reply to
Jeff Layman

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