AE & JE EE Quiz: Electrical Machine Booster Quiz-4

If P₁ and P₂ be the iron and copper, losses of a transformer on full-load, what is the ratio of P₁ and P₂ such that maximum efficiency occurs at 75% full-load?

If the unit impedance of a transformer is , then the minimum possible value of voltage regulation is:

Which of the following is/are disadvantages of auto transformers?

1. If the transformation ration differs far from unity, the economic advantages of autotransformer over two winding transformer decreases.

2. The short circuit current in an auto transformer is higher than that in a corresponding two winding transformer.

Which of the following would refer to an ideal transformer?

1) Winding-resistances are negligible

2) Leakage-fluxes are included

3) Core-losses are negligible

4) Magnetization characteristic is linear

Two 3-ф transformers are operating in parallel then which of the following statement is correct

1. Same voltage rating & same turns ratio

2. The phase sequence must be same

3. Transformers must have the same phase group.

For a transformer

S1: Eddy current loss depends on frequency but not on voltage.

S2: Hysteresis loss depends on frequency and voltage both.

Choose the correct option

Which of the following statement is/are correct about transformer?

1) Core type transformer require more amount of copper as compared to shell type transformer

2) Size of distribution transformer is smaller as compared to similar power transformer

3) Auto transformer has lower p.u impedance as compared to two winding transformer

4) Shell type transformer is suitable for low voltage and low power applications.

In a transformer, ____harmonic is rich in magnetic inrush.