Panasonic Heatpump EMI noise

[Rosch]

I recently installed A Panasonic heatpump, the WH-WDG05LE5 Outside unit with the WH-ADC0509L3E5 inside unit it is a hydraulic split so no messing around with refrigerant. Aside from some detestably stupid decisions regarding non existing air purge valves. The thing works quite well and is relatively quiet. However it sends out some rather annoying noise that I can hear and that my speakers pick up. 6.5kHz. When the inverter compressor turns on the noise starts. So my question is what can I do about it? Added is my measurement setup probably dumb as hell but anyway there it is

[SeanB]

Insufficient mains filtering in the unit, or the power wiring is common to your room, and not a separate connection back to the distribution board. If you are sharing the same socket outlet, most likely, then you need to install a mains filter in the line to the AC unit, rated for it's run current, and another to the equipment in your room. Otherwise a separate cable to the distribution board, and a separate breaker for it, still with a mains filter to the equipment in your room.

[Rosch]

So the interesting thing here is. It has its own circuit breaker, a dedicated run to the mains distribution board. I have a 3 phase supply and have already switched to a different phase, the heatpump is the only thing on this particular phase at the moment. And it made no difference switching phases.

[SeanB]

So it needs a line filter on the supply by the heat pump.

[tomton]

https://gathering.tweakers.net/forum/list_message/84507826#84507826

Hi Rosch, see my message in the Dutch Tweakers forum regarding the same issue on my end. Did you resolve it?

[Rosch]

Sadly not. Irritation about it starts during the fall and is gone in spring... This thing is electrically noisy. Some part in my pc power supply picks it up and resonates at the same frequency when the heatpump is turned on, if you find a solution let me know...

[Randy222]

EMI, or just harmonics put back onto the mains and your radio picks it up.
Run FFT on that Rigol.

[Electrodynamic]

Sadly not. Irritation about it starts during the fall and is gone in spring... This thing is electrically noisy. Some part in my pc power supply picks it up and resonates at the same frequency when the heatpump is turned on, if you find a solution let me know...

Interesting, are you implying the problem is only in heating mode and not cooling?.

[Rosch]

EMI, or just harmonics put back onto the mains and your radio picks it up.
Run FFT on that Rigol.

FFT heatpump off:(I don't think the purple text is correct I think it should say 2.5Mhz instead of 6.25Mhz/Div)

FFT heatpump on:

Sadly not. Irritation about it starts during the fall and is gone in spring... This thing is electrically noisy. Some part in my pc power supply picks it up and resonates at the same frequency when the heatpump is turned on, if you find a solution let me know...

Interesting, are you implying the problem is only in heating mode and not cooling?.

No it will do exactly the same with cooling but the Netherlands just does not get that hot and it isn't sitting around making hot water that often. Because I want the thing to run efficiently it runs on quite low temperatures to improve COP but that means it needs to be on longer to be able to output heat Heating COP last month was an average of 4.2 (outside temperature of 2.1 c) december was 4.7 (outside temperature of 6.2) which is not too bad I think

[Randy222]

Can you validate your FFT calibration
https://www.eevblog.com/forum/testgear/rigol-ds1054z-fft-bug%28s%29/

[WattsThat]

Are the connections between the inverter and the motor realized with shielded cable? It should be. Otherwise those sharp edges of the inverter pwm output are just doing what harmonic rich signals do… they radiate… everywhere. A good earth connection to the motor frame is important as well. Hopefully the grounding to the inverter is done in a star fashion with a common point going back to supply.

I’m unsure if domestic appliances under CE have to meet the emc direcectives in EN 61800-3. If so, it should have been tested and certified to avoid such problems. Filters should be in the appliance if required by compliance testing, it shouldn’t be something you have to add after the fact.

[Psi]

Panasonic heat pumps are known to be quite good quality. Assuming you don't just have a faulty unit where the internal filter isn't working, are you positive the issue is not your speakers being overly sensitive to typical mains noise? Perhaps due to the filters in it failing or just aging.

It's pretty common failure mode for old speaker amps to start humming or picking up mains noise.
I don't doubt you first noticed it when the heatpump was installed and that the heatpump is the source of the noise, but it doesnt mean the heatpump is the issue.

[Rosch]

Can you validate your FFT calibration
https://www.eevblog.com/forum/testgear/rigol-ds1054z-fft-bug%28s%29/

Hmm interesting I shall take a look at that!

Are the connections between the inverter and the motor realized with shielded cable? It should be. Otherwise those sharp edges of the inverter pwm output are just doing what harmonic rich signals do… they radiate… everywhere. A good earth connection to the motor frame is important as well. Hopefully the grounding to the inverter is done in a star fashion with a common point going back to supply.

I’m unsure if domestic appliances under CE have to meet the emc direcectives in EN 61800-3. If so, it should have been tested and certified to avoid such problems. Filters should be in the appliance if required by compliance testing, it shouldn’t be something you have to add after the fact.

To explain more about the situation. There are 2 runs of aproximately 15 meters of pvc conduit going from the breaker panel with 3x 2.5mm2 solid coper wire to 2 distribution boxes 1 for the extra heater and 1 for the heatpump system, L, N and PE. from the disribution boxes there is 2x 2m stranded 3x2.5mm cable going to the indoor units.
The Inside unit has a single flexible cable connection to the outside unit 10 meters of stranded unshielded 4x 2.5mm2 copper the specs of this cable came from the installer manual, Live, Neutral, Ground and Communication. If I remember correctly the wires between the compressor and the control unit are I think 3 strands of wire wrapping once or twice around a ferrite toroid. As can be seen on page 411 https://www.climadirect.com/documenten/service-manual_adc0509l3e5_l3e5an_l6e5_l6e5an_l3e5b_l3e5uk.pdf
I could open it up tomorrow to take some pictures of the grounding situation inside the outside unit.
But I think the real fix would be to add some sort of filter in the outside unit I just don't know what I should look for...

Panasonic heat pumps are known to be quite good quality. Assuming you don't just have a faulty unit where the internal filter isn't working, are you positive the issue is not your speakers being overly sensitive to typical mains noise? Perhaps due to the filters in it failing or just aging.

It's pretty common failure mode for old speaker amps to start humming or picking up mains noise.
I don't doubt you first noticed it when the heatpump was installed and that the heatpump is the source of the noise, but it doesnt mean the heatpump is the issue.

I am quite sure it's the heatpump, multiple parts on this system make the 6.5khz noise the inside unit has the water pump that also generates a 6.5khz whine. I get 6.5khz coilwhine in both my pc power supplies when the compressor is on though so that is the main culprit I think.

[Psi]

It's the culprit yes, but if your speakers had filtered it out you would never have known it was there.

[Siwastaja]

So the elephant in the room, are the speakers active speakers with power supply, with single-ended audio delivered to them over something like a 3.5mm plug?

If so, the whole concept has an inevitable ground loop, and noises cannot be avoided, even if everything passes EMC regulations with flying colors.

In good old days that meant living with mains hum. In late 1990's, that started to get replaced with all sorts of switch mode supply, computer CPU etc. induced varying high-pitched noises. The solutions are removal of ground loops or using differential signaling (balanced audio).

[soldar]

Over the years I have had multiple speakers that would pick up radio noise. Some still do. My computer speakers give that characteristic noise when the mobile phone checks in with the phone network every so often. And before the phone rings with an incoming call I can hear the radio noise in the speakers.

One solution is to place the phone at least 1 or 1.5 meters away. But it does not bother me.

In the past I have corrected this issue by connecting a small capacitor, say 100 pF, across the input to the amplifier. That gets rid of radio noise.  I suppose a better low pass filter would work better but I have never gone that far.