What are bushings in transformers used for?

Question

Question

This question was previously asked in

SSC JE Electrical 06 Jun 2024 Shift 2 Official Paper - 1

They are used to cool the transformer oil.
They are used to filter contaminants from the transformer oil.
They are used to connect the transformer to the power grid.
They are used to insulate the transformer leads as they come out through the tank.

Answer 1

Bushings are essential for the insulation of the leads as they exit the transformer tank.

Bushings:

When a high voltage conductor passes through a metal sheet or frame which is at earth potential, the necessary insulation is provided in the form of bushing.
The primary function of the bushing is to prevent electrical breakdown between the enclosed conductor and the surrounding earthed metal work.
The high voltage conductor passes through the bushing made of some insulating material (e.g., porcelain, steatite).
In transformers, bushings are insulating devices that allow electrical conductors (such as transformer leads) to pass safely through the transformer tank or casing while preventing the high voltage from leaking to the grounded parts of the transformer. Their primary purpose is insulation, ensuring that the high-voltage leads are protected from the tank and the surrounding environment.
Bushings provide a safe way to bring electrical connections out of the transformer without shorting the circuit or causing electrical faults.
They are designed to handle high voltages and currents, while also preventing any potential dielectric breakdown between the conductor and the transformer tank.