Fridge transformer whines

[BobTobb]

I have a wider range of hearing than most people. I can hear the transformer of my fridge when the compressor isn't running. It utterly torments me so I wear noise cancelling headphones all day, every day.

Other refrigerators do this too and shops are too noisy and unhelpful to really test to see if they whine.

1) Is there something I can get an electrician to wire in-line before the transformer that reduces the transformer's need to handle so much voltage when the compressor isn't running?

2) Can I change the transformer to something that doesn't whine? Image attached.

 

[marconi]

What frequency or tone is the whine?

 

[James]

A high frequency wine is not normally a transformer issue. 50hz in U.K. or 60 in the states is what I would expect from a transformer.

 

[marconi]

Sorry to be a pedant but the fundamental of the mechanical vibrations ie the whine is at twice the supply frequency and any non linearities produce 3rd, 5th, 7th … harmonics of this fundamental.

 

[brianmoooore]

Whine from a fridge when the compressor isn't running is usually pressure leaking through the JT valve.

 

[BobTobb]

What frequency or tone is the whine?

About 15,000hz. I'm matching this with an online tone generator. Maybe there's an app that can record and tell me, if you think it's necessary?

 

[BobTobb]

Whine from a fridge when the compressor isn't running is usually pressure leaking through the JT valve.

Would an electrician be able to tell the difference and help fix this? That doesn't seem electrical.

It sound like an electrical sound to me and it sounds like it's coming from that box but I admit that at this very high frequency, it's hard to tell.

 

[marconi]

Good morning from London. If the power supply uses a type of transformer using switched mode technology then it would be operating at an electrical fundamental frequency in the range 25kHz to say 500kHz. The frequency you mention for the whine is 15kHz which is below 25kHz. The mains electrical supply frequency is 50 or 60Hz many octaves below the tone of your whine. This tends to suggest the whine is not electrical in origin.

You are not alone in noticing a whine. See:

How To Fix A Refrigerator Making High Pitched Noise - https://removeandreplace.com/2015/01/19/how-to-fix-a-refrigerator-making-high-pitched-noise/

You might like to carefully hold or touch pipes, components and covers to see if when you do the whine stops. Then we can think about adding some restraint in lieu of your finger.

The Joule-Thomson valve will make a noise:

Joule Thomson or JT Valve - EnggCyclopedia - https://www.enggcyclopedia.com/2019/04/joule-thomson-or-jt-valve/

The JT valve is located between the condenser and evaporator in your fridge and is always in operation since it is a passive device which throttles the flow of the refrigerant gas thereby causing the gas to expand on the outlet side making a noise. It may not be obvious to find.

 

[BobTobb]

Good morning, Big Smoke! Thank you for your help

I gently pressed everything I could to see if that changes the tone; pipes but not behind anything not accessible from the back. I noticed that the tone changed only when I shut and opened the door to the fridge.

Here's a video of the sound with switching the fridge on and off:

Wormhole - Simple, private file sharing

Wormhole lets you share files with end-to-end encryption and a link that automatically expires.

wormhole.app

It still sounds like it's coming from under plastic cover I took a photo of, which I presume is where the power supply is.
As I say, the sound goes away when the compressor cycles ON.

I'd prefer to fix it but If I buy a new fridge what can I do to not be in the same position again in a few year's time?

 

[marconi]

Thank you. I can hear it too. I think it changes in pitch as you turn something on and off. Do you too?

I need to find my earphones and listen again but that will not be until tomorrow morning.

Regards

M

 

[marconi]

What is the model number of your fridge please? Is it a fridge or fridge freezer?

Would you know if the compressor is powered by an inverter which varies the speed of its motor to improve energy efficiency? Panasonic have an ECONAVI range which has this feature

EFFICIENT- ECONAVI & INVERTER Technology - Panasonic India - https://www.panasonic.com/in/consumer/home-appliances/refrigerators/refrigerators-learn/article/efficient-econavi-inverter-technology.html

ECONAVI - https://www.panasonic.com/global/hvac/air-conditioning/introducing/econavi.html#:~:text=ECONAVI%20Intelligent%20Sensors%20detect%20unconscious,with%20uninterrupted%20comfort%20and%20convenience.

An inverter for motor control will contain a device called an oscillator which could be the source of the whine.

The link indicates the ECONAVI controller has some basic artificial intelligence to learn about door openings and quiet times when the fridge door is not opened such as overnight. The obvious sensor for detecting overnight is a light sensor. But this may be supplemented by an ultrasonic sensor listening out for movement near the fridge - the air conditioners Panasonic make which are ECONAVI use ultrasonic sensors because a light sensor may not be suitable in all installations where ambient light never reduces enough to indicate it is night time.

How old is it?

Please take a picture or send me the part number details of the white component you thought contained a whining transformer

 

[marconi]

Do you have this refrigerator -NR-BP280VD - which has a high pitched whine others have noticed. It has an inverter. The motor operates at a higher frequency - its is marked with a power supply frequency range of 51 to 225Hz not the usual single 50 or 60Hz:

 

[marconi]

If your fridge is indeed an inverter powered compressor then what you are I think hearing are the high frequency current pulses to the motor something similar to what you hear when a modern underground train pulls away from the platform and the traction electronics pulse current to the axle motors. Can you hear the initial very high pitch when pulsed current is first applied to the stationary traction motors in this clip? Obviously the traction motors of a train do not run up in speed as quickly as the much smaller and more lightly loaded motor powering a fridge compressor so there is a clever changing pattern of pulses to begin with to cause the traction motors to accelerate up to speed - you can hear this changing pattern.

If I am correct then other than attempting to dampen the sound - which I do not at all suggest because there are other considerations to do with ventilation, cooling, heat transfer and fire rating - you would be rid of this irritating noise by buying an older technology fridge with a compressor that only runs at 50 or 60 Hz.

here is a short piece which mentions the high frequency noise for a motor driven by an inverter:

The noise of variable frequency drive fed motors - http://www.gozuk.com/blog/the-noise-of-vfd-fed-motors-629827.html

Now sometimes the voltage and frequency are changed to vary the speed of the motor. But there are other schemes which keep the same voltage and frequency but vary the on to off ratio of the current pulses - so their whine has a constant tone - pulse width modulation.

 

[marconi]

BobTobb- hello again. Is what I have posted any help to you?