Why Transformer Cores Must Be Grounded

1. Why does the core of a transformer need to be grounded?
If the core is not grounded, an induced voltage will build up on it. Furthermore, if an external voltage is applied and this induced voltage exceeds the breakdown voltage to ground, internal discharging will occur within the transformer. This can severely damage the equipment and pose significant safety hazards. Therefore, grounding the core is essential to prevent this from happening.

2. What is the purpose of the shading ring embedded in the iron core of an AC contactor?
The shading ring embedded in the iron core serves several key functions:

• Function 1: It reduces the humming noise generated by the alternating current in the coil.

• Function 2: It eliminates residual magnetism in the core, allowing the contactor to release its magnetic energy quickly after being powered off. 

• Function 3: It minimizes interference, ensuring smoother engagement of the electromagnet and eliminating mechanical vibrations.