- #1
the Physic freak
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If a transformer has loose parts, then a hum is heard while there is current flowing through the primary coil. how do you explain this noise?
Understanding Transformer Noise: Causes and Solutions
- Thread starter the Physic freak
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Discussion Overview
The discussion focuses on the causes of noise in transformers, particularly the hum heard when current flows through the primary coil. Participants explore various factors contributing to this phenomenon, including mechanical and magnetic interactions within the transformer components.
Discussion Character
- Exploratory
- Technical explanation
- Homework-related
- Debate/contested
Main Points Raised
- Some participants suggest that loose parts in the transformer lead to audible hum due to vibrations caused by the changing magnetic field.
- Warren proposes that the loose parts are pulled back and forth by the magnetic field, contributing to the noise.
- There is a discussion about the nature of the loose parts, with questions raised about whether they are metal and what specific components might be involved.
- Participants mention that laminations in the transformer can repel each other if not adequately clamped, leading to humming or rattling sounds.
- It is noted that the coil can also experience forces from the changing magnetic field, resulting in movement and sound.
- Several sources of hum are identified, including loose laminations, loose coil windings, and magnetostriction of iron.
- Shahvir introduces the concept of magnetostriction, explaining that it results from the elongation and contraction of core laminations, contributing to noise due to vibrations.
- Additionally, magnetic forces between windings when the transformer is loaded are mentioned as a potential source of noise.
Areas of Agreement / Disagreement
Participants express multiple competing views regarding the sources of transformer noise, with no consensus reached on a singular explanation. Various hypotheses are presented, and the discussion remains unresolved.
Contextual Notes
Some assumptions about the nature of the loose parts and the specific mechanisms of noise generation are not fully explored, leaving room for further inquiry.
- #2
chroot
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Sounds like a homework problem. What are your thoughts?
- Warren
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- #3
the Physic freak
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could it be because the coil vibrates?
- #4
chroot
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Well, the loose part -- whatever it is -- is pulled back and forth by the changing magnetic field, right?
- Warren
- Warren
- #5
the Physic freak
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oh ic, thanks a lot ^^
- #6
Averagesupernova
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chroot said:
I envision the following inserted in the answer space of a homework question: The loose part -- whatever it is -- is pulled back and forth by the changing magnetic field.
- #7
chroot
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Yeah, well, you can't win 'em all. 
- Warren
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- #8
the Physic freak
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what do you mean averagesupernova?
- #9
fawk3s
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whats the loose part? and how can you be sure its metal :P?
- #10
vk6kro
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Hint:
Go to Wikipedia and look for Laminated Steel Cores under Transformers.
http://en.wikipedia.org/wiki/Transformer
Go to Wikipedia and look for Laminated Steel Cores under Transformers.
http://en.wikipedia.org/wiki/Transformer
- #11
vk6kro
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Just to wrap this one up a bit...
The laminations in a transfromer all get the same magnetic polarity induced in them by the changing current in the coil, so they tend to repel each other. If they are not adequately clamped, they can tend to hum or even rattle a bit.
Likewise, the coil interacts with this changing magnetic field and it can experience forces, too. So you can get coil movement and corresponding sounds.
The laminations in a transfromer all get the same magnetic polarity induced in them by the changing current in the coil, so they tend to repel each other. If they are not adequately clamped, they can tend to hum or even rattle a bit.
Likewise, the coil interacts with this changing magnetic field and it can experience forces, too. So you can get coil movement and corresponding sounds.
- #12
Bob S
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There are three possible sources of hum:
Loose lamination(s)
Loose coil or coil windings
Magnetostriction of iron
Loose lamination(s)
Loose coil or coil windings
Magnetostriction of iron
- #13
negitron
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Four, if you count loose mounting hardware as part of the transformer.
- #14
b.shahvir
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The hum is due to property of 'magnetostriction' exhibited by ferromagnetic materials. It is due to the elongation and contraction of the core laminations at 100 times/sec (for 50Hz supply) and causes noise due to vibrations. Go to wikipedia and search for 'magnetostriction', you will get the detailed theory for the same.
The hum is also due to the magnetic forces of attraction and repulsion between the primary and secondary windings as well as between identical windings when the transformer is considerably loaded.
Shahvir
The hum is also due to the magnetic forces of attraction and repulsion between the primary and secondary windings as well as between identical windings when the transformer is considerably loaded.
Shahvir