Other Types of Transformers

Different Types of Transformers

• Electrical Transformers: Designed for various uses and purposes, following the same fundamental principles.

1. Power Transformers

• Uses:

  • Step-up: Transmit electrical energy from power stations (25 kV–400 kV).

  • Step-down: From 400 kV to 132 kV, and 132 kV to 11 kV, and 11 kV to 400 V for distribution.

  • Convert mains voltage (230 V) to extra-low voltage for electronic equipment.

  • One-to-one: Maintain the same input and output voltage, e.g., 230 V shaver points for safety.

• Construction: Insulated laminations to minimize eddy currents. Oil coolant is used in large transformers for insulation and cooling, while smaller transformers may use air-cooling methods. Cast resin power transformers are safe for indoor use.

2. Current Transformers

• Application: Accurate current measurement (e.g., Class X CTs).

• Operation: AC in the primary conductor creates a magnetic field, inducing current in the secondary winding; proper coupling ensures accurate readings. Open circuits can cause high voltage discharges.

3. Isolation Transformers

• Purpose: Provide electrical separation for safety. Can step up, step down, or maintain 1:1 ratio.

• Design Features: Enhanced insulation and electrostatic shielding. Often used in domestic shaver sockets to minimize shock hazards and in medical environments for safety (medical isolated power supplies).

4. Voltage Transformers

• Structure: Consists of two windings around a common core used for potential measurement.

5. Earthing Transformers

• Function: Establish a physical neutral point for power transformers with delta-connected secondaries, suitable for various earthing systems with low impedance.

Transformer Core Types

• Core Type:

  • Shell Type: More efficient; magnetic flux circulates through two paths.

  • Core Type: Channels flux through a single path, resulting in leakage flux at core corners.