Apertured electrical coil for noise reduction

Reduction of the acoustic radiation of the coils present in the electricity distribution networks, while preserving the value of the inductance of the coil

Market challenges
The coils used to regulate the current in the electricity distribution networks are subjected to electromagnetic forces resulting from the alternating current which feed them. These stresses cause vibrations and acoustic radiation which can create noise pollution.
Currently the solution is an encapsulation (waterproof structure with sound absorbing material), that requires a posteriori treatment, which poses a cooling problem and whose effectiveness is limited at low frequencies.

Innovative solution
The invention consists in adding air-flowing space between each turn or group of turns so as to reduce the mechanical-acoustic conversion of the vibrations of the coil induced by electromagnetic forces.
The presence of air space between the turns creates an acoustic short circuit, which greatly reduces the acoustic radiation efficiency of the coil.

Development status
A digital simulation has shown that the concept enables the reduction of the noise of the coils (-10 to -30 dB). Prototypes are currently being developed in the laboratory