Citat:
Uporabnik Gatto pravi:
#Misliš da ni mogoče, da bi ob tem nastal zvok, ker zaradi spremenljivega magnetnega polja domene ves čas spreminjajo smer?#
Ni mogoče...pa brez zamere, Sherlock.
MEASURING ACOUSTIC NOISE EMITTED BY POWER TRANSFORMERS
http://www.briangladstone.com/...ransformers.pdf
WHY AND HOW POWER TRANSFORMERS PRODUCE ACOUSTICAL NOISE
There are three physical phenomena that produce noise in the magnetic core [1-16]:
1. The movement of the 90-degree Bloch walls inside the magnetic domains, frequently called Magnetoacoustic
Emission (MAE); see Figure 1.
2. The rotation of the magnetic domains, that is responsible for the bulk magnetostriction; see Figure 2.
3. The Lorentz Force Acoustic Signal (LFAS) causing mechanical forces between laminations of the core;
In general: magnetostriction, occurring near saturation of the core, is the main cause of the acoustical transformer
noise, while LFAS largely depends on the construction of the core. Due to magnetostriction the core vibrates at the
fundamental mains frequency and its harmonics and at core resonance frequencies. In this regard it is important to
notice that a noisy transformer means that a) the transformer is badly constructed -or- b) that the transformer is
forced to operate in a magnetic region close to or at core saturation.
No pa zdaj vsi vemo nekaj več...