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The Mansion, Building Research Establishment, Bucknalls Lane, Watford, Hertfordshire, WD25 9XX, United Kingdom

Noise control technology for power transformers

We use a patented Acoustic Metamaterial technology known as Sonic Crystals, which are artificially fabricated materials designed to control direct, and manipulate sound. Our Sonic Crystal based noise reduction technology is a passive method that superimposes disturbing noise with scattered anti-acoustic noise, which cancels the disturbance.

Our technology scatters sound at key frequencies that is fully out of phase with respect to the noise, and cancel each other out. This is known as total destructive interference. Depending on the application, this method of noise reduction achieves an attenuation of over 95% of sound intensity or 30 dB(A)+ for middle and low frequencies.

Our technology is specifically designed to attenuate at key frequencies in a typical noise spectrum for a power transformer giving 30 dB(A) + attenuation at dominant frequencies.

Transformer noise (hum) is caused by the extension and contraction of the core laminations when magnetized (a phenomenon known as magnetostriction). This extension and contraction (vibration) takes place twice during a normal voltage or current cycle.

That is, the transformer vibrates mainly at twice the frequency of the supply, i.e. 120 Hz or 100 Hz and the higher order harmonics of the fundamental frequency (240, 360, 480 Hz) are also present in the spectrum of the consequent noise. Load noise mainly is generated by windings vibrations caused by the electromagnetic forces as a result of the interaction of load current and leakage flux produced by this current. The main frequency of this sound, therefore, is twice the supply frequency. The level of load noise is determined by load current, winding design and the type of tank shielding used.

Our Patented technology enables significant noise attenuation for middle and low frequencies than traditional passive noise control measures. Until now, low frequencies could only be attenuated using high masses. These however require extensive constructional measures that are often impossible to implement. The application area for our technology includes products that require limited space, limited masses and a low noise level. This makes it possible to provide noise control measures and attenuate noise in the most comprehensive and cost effective manner.

We work with manufacturing partners and prime contractors to deliver quality noise reduction technologies that are cost effective over their lifetime with enhanced flexible solutions. If you want your products to become the quietest in their field, We help you to extend your competitive edge in technology.

Our technology is already in use or in the development stage in the following applications:

  • Power & Distribution Transformers
  • Compressors and Pumps
  • Gas Turbines
  • Extraction Units
  • Industrial Engineering Applications

If you want your products to become the quietest in their field, give us a call today on 01926 676118 or email info@sonobex.com and find out more about our patented noise reduction technology.Subscribe to our blog for regular updates or follow us on the social networks: