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Author Topic: Variable speed pool pump? The "machine transmitter" is back!  (Read 2529 times)
AC5XP
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Posts: 2




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« on: February 21, 2019, 11:28:12 AM »

My old pool pump (equipped with a simple single-phase induction motor) gave up after ten years, so it was time to buy a new one. Since these pool pumps take 2.5kW from the grid (causing a $90 increase to my electricity bill each month at 8 hours of operation a day), I decided to look into a variable speed pool pump. They allow you to run it at much lower speeds for a certain period of the day, running at peak power for only 2 hours a day or so - such an RPM regime keeps your pool just as clean.
So I bought a top-of-the line model, the Pentair Superflo VS. After installation I must say I was quite pleased; it is acoustically very quiet; it does not run as hot as the old one, does not need a startup capacitor that can go bad and saves me at least $40 a month in electricity.
So after all that hard installation work I decided to do some hamming. Turned on my transceiver and immediately noticed an S-7 noise level on 20 meter, WITHOUT the preamp switched in. After some fiddling with wall adapters and light switches (those LED bulbs and phone chargers also cause a lot of noise) I suddenly remembered my new pool pump which was running at that very moment. Went out; turned it off; got back in the shack and you guessed it - the noise was gone. Unbelievable; it looks like NO manufacturer observes EMC regulations any more, not even the reputable ones. And the FCC does not seem to care much either judging all the China crap that enters the US unhindered nowadays, without any EMC approvals.
Why does this pump cause so much EM noise? Well, it has one of those electronic high-frequency choppers in it. The incoming single-phase AC is rectified and then converted to 3-phase AC with variable frequency and amplitude, depending on the selected RPM. It does this with high-frequency MOSFET choppers using pulse-width modulation, with excellent efficiency, but tremendous EM noise from higher harmonics.
Of course, it is possible to filter this out with the right filters. But those are bulky at these high currents, and expensive. So the manufacturer just omits it, thinking: "No one listens to AM radio any more, who cares"? So it looks like I will have to install an external filter, but my experience with EMC issues is that there is no guarantee this will fix it.

In my neighborhood, with its 10kV above-ground wiring, listening to the 160, 80 and 40 meter bands has become almost impossible, already for many years. On 160 meter my noise level is S9+20, on 80m it is S9, and on 40 meter it is S7, with only the strongest stations making it. Even on 20 meter, my noise level is still in the S-3 range. And it is getting worse every year, now that incandescent light bulbs are a thing of the past. For example, I used to be able to make 60 meter contacts to Europe when that band was new, today that is a complete impossibility.

Despite what we like to believe ("Amateur emergency service" and the like), Washington legislators do not care about hams, not on the left and not on the right. Their reasoning: Not enough people to have an impact in the voting booth. Couple that to the fact that broadcast AM also loses interest fast with the general population (be it on the medium wave or short wave), and there you have it - who cares about the fact that all our consumer products are strong EMI emitters these days? As long as the smart phones do the job, no big deal!
And I am not even talking about the rise of electric cars - they have even more powerful electronic choppers than my pool pump, and give off SO much interference that Tesla does not even bother to put AM band capability on their car radios any more.
What does all this mean for ham radio? "Dead man walking", I'm afraid.....
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K0UA
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Posts: 4607




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« Reply #1 on: February 21, 2019, 01:30:16 PM »

I would have noted the variable speed on on the label and not bought it. Knowing that variable anything is a recipe for RFI disaster. ANY new purchase you bring into your home must be thoroughly "vetted" before purchase, as it is about guaranteed to cause RFI. Yep the noise floor is rising worldwide, and it is NOT just local in nature, as wiring in our homes and power lines make pretty good RF radiators.  In my mobile installation I can hear a Pruis coming down the road before I can see it. We don't have Tesla's around here.
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73  James K0UA
ARRL Missouri Technical Specialist
WB4SPT
Member

Posts: 777




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« Reply #2 on: February 25, 2019, 11:44:18 AM »

Yep, its bad.   Google "EMC" and note the results.   The first page of hits doesn't even relate to "ElectroMagnetic Compatibility".  Its a new world, one which is not particularly dependent on HF comm.  to wit:

 Loran-gone;  WWV broadcast- almost gone;  Military HF-almost gone; High seas HF telephone- gone;  Marine maydays on HF- gone;  AM BCB- gone from the newest, most sophisticated cars;  etc.
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KL7CW
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Posts: 577




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« Reply #3 on: February 25, 2019, 01:26:20 PM »

If you cannot reasonably filter out the RFI, have you considered simply rigging up a remote switch in your shack to temporarily turn off the pool motor during your operating session.  Probably you could do this at a low voltage control point, either with wires or possibly even with a wi fi switch or whatever.  I doubt that your pool cares exactly when the motor runs and even if it did not run the full 24 hours during a contest, I doubt that the pool would suffer.  This is just an idea to consider.  You could even use something like a wind up timer so if you forgot to turn the motor off, it would automatically start again after the hour or two you set it for.  This is not a perfect solution, but just an idea if other methods fail.
                Rick  KL7CW
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WB4SPT
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Posts: 777




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« Reply #4 on: February 25, 2019, 03:37:22 PM »


Of course, it is possible to filter this out with the right filters. But those are bulky at these high currents, and expensive. So the manufacturer just omits it, thinking: "No one listens to AM radio any more, who cares"? So it looks like I will have to install an external filter, but my experience with EMC issues is that there is no guarantee this will fix it.



Mix 31 on the 3 phase controller output, near the PCB.   All 3 into one toroid (several wraps), or separate barrels for each lead.  It may also take a corcom line filter; up to about 16Amp models are not too expensive.   Look at the plots near 4 to 15 MHz to give you an idea where they are most effective. 
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LA9XNA
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Posts: 264




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« Reply #5 on: February 26, 2019, 09:41:35 PM »

I'm an electrician and when we install a VFD (Variable Frequency Drive) we always use a specialiced cabel for the VFD.
The reason for this is to reduce the RFI from VFD. See the links at the bottom before you start any work.
start on 1 and work your way down until the RFI gets better or the money stops you.

My suggestion for you to reduce the rfi is:
1. Enshure that all groundings are propperly connected with a low impedanze fonntion to the main PE (Protective earth). If the pump is supplied from a pluged supply use a junction box or switch for a direct supply.
2. Replace the cable form the VFD to the motor with propper VFD cable.
2a. Check if it is possible to change the chopping frequency of the VFD. Your RFI is probably harmonics of the chopping frequency.
3. Use Clipon ferrites to kill more RFI.
4. Buy a separate RFI filter.
5. If the VFD is some unknown brand replace it with an known brand (Omron, ABB, Siemens, Eaton, Allan Bradly and others). If you go form a two phase system to a 3 phase system the VFD must be 3 times the the motor rating if its a 3ph to 3ph converter.
6. You get what you pay for!!!

https://www.belden.com/products/industrial/cable/vfd
https://www.belden.com/blog/industrial-ethernet/why-high-performance-vfd-cable-is-important
https://www.tpcwire.com/blog/vfd-what-it-is-and-why-using-vfd-cable-matters
http://www.vfds.org/vfd-and-rfi-708163.html
https://kebblog.com/7-steps-to-reducing-emi-with-vfds/
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KD0REQ
Member

Posts: 2389




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« Reply #6 on: February 27, 2019, 01:09:40 PM »

I don't know the code for pool pumps, but I do know all metallics including the whirlpool tub pump/motor must be connected with a minimum #8 ground lead to eliminate the chance of differential resistances causing current to flow through them, zapping anybody in that tub who might touch something else metal. with it there, treat it like an antenna ground field... ground rod at the pump if outside, and thence straight to the entrance panel. if the wiring is inside BX or EMT, you will have additional Faraday shield protection.
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WB4SPT
Member

Posts: 777




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« Reply #7 on: February 28, 2019, 06:32:22 AM »

I'm an electrician and when we install a VFD (Variable Frequency Drive) we always use a specialiced cabel for the VFD.
The reason for this is to reduce the RFI from VFD. See the links at the bottom before you start any work.
start on 1 and work your way down until the RFI gets better or the money stops you.

My suggestion for you to reduce the rfi is:
1. Enshure that all groundings are propperly connected with a low impedanze fonntion to the main PE (Protective earth). If the pump is supplied from a pluged supply use a junction box or switch for a direct supply.
2. Replace the cable form the VFD to the motor with propper VFD cable.
2a. Check if it is possible to change the chopping frequency of the VFD. Your RFI is probably harmonics of the chopping frequency.
3. Use Clipon ferrites to kill more RFI.
4. Buy a separate RFI filter.
5. If the VFD is some unknown brand replace it with an known brand (Omron, ABB, Siemens, Eaton, Allan Bradly and others). If you go form a two phase system to a 3 phase system the VFD must be 3 times the the motor rating if its a 3ph to 3ph converter.
6. You get what you pay for!!!

https://www.belden.com/products/industrial/cable/vfd
https://www.belden.com/blog/industrial-ethernet/why-high-performance-vfd-cable-is-important
https://www.tpcwire.com/blog/vfd-what-it-is-and-why-using-vfd-cable-matters
http://www.vfds.org/vfd-and-rfi-708163.html
https://kebblog.com/7-steps-to-reducing-emi-with-vfds/

an excellent response.  Clearly, you are from a country that cares about this stuff!   Smiley
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LA9XNA
Member

Posts: 264




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« Reply #8 on: February 28, 2019, 07:07:22 AM »

I don't know the code for pool pumps, but I do know all metallics including the whirlpool tub pump/motor must be connected with a minimum #8 ground lead to eliminate the chance of differential resistances causing current to flow through them, zapping anybody in that tub who might touch something else metal. with it there, treat it like an antenna ground field... ground rod at the pump if outside, and thence straight to the entrance panel. if the wiring is inside BX or EMT, you will have additional Faraday shield protection.
I dont know anything about the US electrical code but fromyour description this is a equiponentional grounding to ensyoure that if you com in contact with to pices of the electrics for your pool you will not get shocked.

For VFDs you must think in the lines of HF grounding by using multistrand and Copper bands for the protective earth (PE).

I forgot to mention that you should also see if there is something to do with your radio station grounding. If you have a try to disconnect it from the house PE and see if it improves.
In case it improves you can hammer down a separate PE bar or run a PE groundwire only for the HAM s gear.
Use a barfot station only the tranciever and power supply (battery in case you have the posibility) because this will reduce the number of places that can pick up noise.
Stay away form endfed antennas bacause these will pick up more noise, balanced antennas like loops and dipoles are the best.
By the way do not daisy chain the groundings on your HAM gear. Have a common earth bar for your station and run a thich wire to your ground electrode.
If the PE from your pool pumpe is connected at more or less the same place as the one from your schack the noise will bleed over between the two groundings.

Jhesc sopme of the links in the google search.
https://www.google.com/search?q=grounding+of+radio+station&oq=grounding+of+radio+station&aqs=chrome..69i57j0.12439j1j7&sourceid=chrome&ie=UTF-8
« Last Edit: February 28, 2019, 07:20:30 AM by LA9XNA » Logged
W9IQ
Member

Posts: 3397




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« Reply #9 on: February 28, 2019, 08:14:24 AM »


I dont know anything about the US electrical code but fromyour description this is a equiponentional grounding to ensyoure that if you com in contact with to pices of the electrics for your pool you will not get shocked.

For VFDs you must think in the lines of HF grounding by using multistrand and Copper bands for the protective earth (PE).

I forgot to mention that you should also see if there is something to do with your radio station grounding. If you have a try to disconnect it from the house PE and see if it improves.

In case it improves you can hammer down a separate PE bar or run a PE groundwire only for the HAM s gear.

If the PE from your pool pumpe is connected at more or less the same place as the one from your schack the noise will bleed over between the two groundings.

In the US, if the local jurisdiction requires adherence to the NEC (National Electric Code), then the PE ground rods must be bonded together. This rules out the notion of separate PE grounds for the station and the house/pool. The purpose is to ensure a near equipotential of the safety ground in the event of the failure of a neutral wire connection.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
LA9XNA
Member

Posts: 264




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« Reply #10 on: February 28, 2019, 12:25:10 PM »


I dont know anything about the US electrical code but fromyour description this is a equiponentional grounding to ensyoure that if you com in contact with to pices of the electrics for your pool you will not get shocked.

For VFDs you must think in the lines of HF grounding by using multistrand and Copper bands for the protective earth (PE).

I forgot to mention that you should also see if there is something to do with your radio station grounding. If you have a try to disconnect it from the house PE and see if it improves.

In case it improves you can hammer down a separate PE bar or run a PE groundwire only for the HAM s gear.



If the PE from your pool pumpe is connected at more or less the same place as the one from your schack the noise will bleed over between the two groundings.

In the US, if the local jurisdiction requires adherence to the NEC (National Electric Code), then the PE ground rods must be bonded together. This rules out the notion of separate PE grounds for the station and the house/pool. The purpose is to ensure a near equipotential of the safety ground in the event of the failure of a neutral wire connection.

- Glenn W9IQ

No not necessarily because the ground for the hamstation is not a PE ground for the power system, but a signal ground for the ham station.
It is important to be aware that there are diffrent kinds of earth systems.
Yes they have to connected together at the earth electrode because of balancing out equiptentional voltages.
By tie the earth systems fogether by the earth electrode the noise will be reduced.

I work in the Oil industry in Norway and we have 3 systems for grounding.
1. PE ground that is the protective earth for equipotentional ground.
2. Instrument ground (IE) that is a signal reference ground used for instrument purposes.
3. Intrinsically safe ground (IS) that is used for EXi equipment.

In medical installations there are two earth systems.
1. PE
2. Medical earth (this is more or less the same as a IE earth used in the oil industry)
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AC5XP
Member

Posts: 2




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« Reply #11 on: March 01, 2019, 01:27:01 PM »

Well, I ordered a 20A EMC filter and installed it today. I also put a shielded cable between the filter and the pump, and grounded it all of course.
Guess what - the problem is gone. From S7 noise on 20 meter I am back to my "normal" S3 noise level on 20 meter, regardless if the pump runs or not, and regardless of selected RPM.
I have tried to attach a photo of the filter, but that does not seem to work here. So I will give you the credentials instead. Manufacturer: Schaffner. Model: FN2060-20-06
Prices vary wildly; the lowest price I could find was $25 (plus shipping)

73s, Luke AC5XP
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W9IQ
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Posts: 3397




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« Reply #12 on: March 01, 2019, 01:39:17 PM »



Congrats, Luke on tackling the problem. Thanks for sharing how you did it.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
K0UA
Member

Posts: 4607




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« Reply #13 on: March 01, 2019, 02:53:05 PM »

Well, I ordered a 20A EMC filter and installed it today. I also put a shielded cable between the filter and the pump, and grounded it all of course.
Guess what - the problem is gone. From S7 noise on 20 meter I am back to my "normal" S3 noise level on 20 meter, regardless if the pump runs or not, and regardless of selected RPM.
I have tried to attach a photo of the filter, but that does not seem to work here. So I will give you the credentials instead. Manufacturer: Schaffner. Model: FN2060-20-06
Prices vary wildly; the lowest price I could find was $25 (plus shipping)

73s, Luke AC5XP

Excellent!.  Glad you posted back your solution.
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73  James K0UA
ARRL Missouri Technical Specialist
N1OEY
Member

Posts: 41




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« Reply #14 on: March 11, 2019, 09:42:40 AM »

I'm going to pay close attention to this thread as we have the same pool pump and I am in the process of getting my two antennas up. Thank you.

I did find the part mentioned at Amazon for relatively the same cost.

https://www.amazon.com/SCHAFFNER-FN2060-20-06-POWER-FILTER-734UA/dp/B00DDE7MXS/ref=sr_1_fkmr0_1?keywords=Schaffner.+Model%3A+FN2060-20-06&qid=1552322533&s=gateway&sr=8-1-fkmr0
« Last Edit: March 11, 2019, 09:46:21 AM by KM6ZRR » Logged
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