Question 1

What causes resistive loss in transformers?

Accepted Answer

Resistive loss occurs when current flows through copper coils with significant resistance, causing energy dissipation through Joule heating. This loss can be minimized by using thicker wires with low resistance in the primary and secondary windings, reducing the heat generated during power transmission.

Question 2

How do eddy currents form in transformer cores?

Accepted Answer

Eddy currents result from varying magnetic fields in the iron core, circulating throughout the conducting material and causing heat losses. These losses can be decreased by using a laminated core made of insulated thin sheets, which narrows eddy current paths and reduces heat dissipation significantly.

Question 3

What is hysteresis loss and how is it reduced?

Accepted Answer

Hysteresis loss occurs due to repeated magnetization and demagnetization of the core by alternating input current. It is reduced by using a highly permeable magnetic core material, such as soft iron with a narrow hysteresis loop, which minimizes the energy retained during magnetization cycles.

Question 4

Why does flux loss occur in transformers?

Accepted Answer

Flux loss appears when the magnetic flux produced in the primary coil is not entirely linked to the secondary coil, resulting from design inefficiencies. A shell-type core design can be used to reduce flux loss by ensuring better magnetic coupling between the primary and secondary windings.

Question 5

How does transformer efficiency relate to energy losses?

Accepted Answer

Transformer efficiency is expressed as the ratio of output power to input power. In ideal transformers, all primary power transfers to the secondary winding, but real transformers always experience energy losses, making output power less than input power. Understanding power in an AC circuit helps explain these efficiency calculations.

Question 6

What is the purpose of laminating transformer cores?

Accepted Answer

Laminated cores consist of thin insulated sheets stacked together, creating large electrical surface resistance that confines eddy currents to individual laminae. This design narrows the paths for eddy current circulation, reducing the induced electromotive force and significantly decreasing heat losses in the transformer core.

Question 7

How do ideal and real transformers differ in power transfer?

Accepted Answer

Ideal transformers assume no energy losses, transferring all primary winding power to the secondary winding. Real transformers always have energy losses through four mechanisms: resistive heating, eddy currents, hysteresis, and flux leakage, resulting in secondary output power being less than primary input power.

变压器的能量损失