Final answer:
Dry-type distribution transformers are equipped with dampers to reduce mechanical noise due to vibration. Vibrations at twice the frequency of the AC power involved are caused by magnetic forces. Counter-wound heating coils in electric appliances can cancel out magnetic fields and minimize vibrations.
Step-by-step explanation:
Dry-type distribution transformers are equipped with dampers to reduce mechanical noise due to vibration. Dampers control the movement and vibration of the transformer components by absorbing the energy and reducing the impact of vibrations.
Vibrations in transformers at twice the frequency of the AC power involved are caused by magnetic forces. When the AC current alternates direction, it creates a magnetic field that interacts with the iron core of the transformer, resulting in mechanical vibrations.
By using counter-wound heating coils or other design features, the magnetic fields in electric appliances like clothes dryers can be cancelled out, reducing the mutual inductance and minimizing vibrations.