TRIPURARI said:
when the transformer is working,it produce a sound gnnnnnnnnnnnn.,why.
The technical designed for all Power Transformer was base on Primary winding and Secondary wind, primary wind is the input connection while the secondary wind is output connection, the sound produced by the transformer is called Humming due to the electro-motive force between the wind and secondary wind. hope this will solve your problem.
Note: The winding copper coil inside the primary and secondary side of the power transformer.