A transformer question?

  • #1
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?
 

Answers and Replies

  • #2
chroot
Staff Emeritus
Science Advisor
Gold Member
10,226
36
Sounds like a homework problem. What are your thoughts?

- Warren
 
  • #3
could it be because the coil vibrates?
 
  • #4
chroot
Staff Emeritus
Science Advisor
Gold Member
10,226
36
Well, the loose part -- whatever it is -- is pulled back and forth by the changing magnetic field, right?

- Warren
 
  • #6
Averagesupernova
Science Advisor
Gold Member
3,848
774
chroot said:
Well, the loose part -- whatever it is -- is pulled back and forth by the changing magnetic field, right?

- Warren

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
Staff Emeritus
Science Advisor
Gold Member
10,226
36
Yeah, well, you can't win 'em all. :frown:

- Warren
 
  • #9
342
1
whats the loose part? and how can you be sure its metal :P?
 
  • #11
vk6kro
Science Advisor
4,081
40
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.
 
  • #12
4,662
5
There are three possible sources of hum:
Loose lamination(s)
Loose coil or coil windings
Magnetostriction of iron
 
  • #13
negitron
Science Advisor
842
1
Four, if you count loose mounting hardware as part of the transformer.
 
  • #14
284
25
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.

Best regards,
Shahvir
 

Related Threads on A transformer question?

  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
14
Views
2K
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
4
Views
1K
  • Last Post
Replies
10
Views
1K
  • Last Post
Replies
11
Views
2K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
20
Views
6K
Replies
5
Views
776
Top