Transformer Interview Questions with Answers?

Transformer Interview Questions

Transformer works on which principle?

Answer: Electrical Transformer works on Faraday's law of electromagnetic induction. In electrical transformer the emf induced will be of Stationary Induced EMF. In stationary induced emf, emf will be induced in such a manner that the electrical conductors (windings) are kept stationary and magnetic field is varied ( varying magnetic field in transformer core) results in production of induced emf.

Why efficiency of transformer is high?

Answer: Electrical transformer is a static device which transfers the power from one circuit to other through electromagnetic induction. In electrical transformer as there are no moving parts, no friction and windage losses occur and other losses in transformer are less as magnetic path of a transformer is a closed loop ( no air gap exist like induction motor between two circuits). Losses in the transformer are very less compared to any other rotating machine, hence efficiency of transformers will be very high. Efficiency will be of the order of 95% to 98%.

Related Topics Transformer Maximum Efficiency Condition Inrush Currents in Transformer DC Supply to Transformer Transformer Parallel Operation Condition Transformer Interview Questions Answers:2 Transformer Voltage Regulation Transformer Testing Methods Transformer Interview Questions Answers:3

What is the emf equation of transformer?

Answer: emf equation of transformer E = 4.44*f*N*φ_max volts

f =  applied frequency of voltage wave

N = Number of turns on primary or secondary winding.

φ_max = Maximum flux ( φ_max = B_max x A)

B_max = Maximum flux density

A =  Area of cross section of the core.

What is the Ideal transformer?

Answer: Transformer which has characteristics such as no winding resistance, no magnetic leakage, no iron loss or core loss ( hysteresis and eddy current loss), and zero magnetising current is termed as Ideal Transformer. Ideal transformer is assumed for better explanation and understanding of practical transformer.

What is the Significance of  voltage per turn?

Answer: Voltage per turn for primary winding side and secondary winding side of the transformer is same. This helps in explaining that primary and secondary of transformers are related to each other by turns ratio (K).

( V1/N1) = ( V2/N2) = K (turns ratio).

(V2/V1) = (E2/E1) = (N2/N1) =K