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Electrical Machines-Transformer MCQ-2 Question 6:-

The flux created by the current flowing through the primary winding induces emf in

(a) primary winding only.
(b) secondary winding only.
(c) transformer core only.
(d) both primary and secondary windings.

Ans: (d) both primary and secondary windings.

Electrical Machines-Transformer MCQ Question 7:-

The primary and secondary windings of a power transformer always have

(a) a common magnetic circuit.
(b) separate magnetic circuits.
(c) wire of the same size.
(d) same number of turns.

Ans: (a) a common magnetic circuit.

Electrical Machines-Transformer MCQ Question 8:-

If the applied voltage to a transformer primary is increased by keeping the V/f ratio fixed, then the magnetising current and the core loss will, respectively:

(a) decrease and remain the same.
(b) increase and decrease.
(c) both remain the same.
(d) remain the same and increase.

Ans: (d) remain the same and increase.

Electrical Machines-Transformer MCQ Question 9:-

The applied voltage of a certain transformer is increased by 75%; while the frequency of the applied voltage is reduced by 25%. The maximum core flux density will:

(a) increase by seven times.
(b) increase by three times.
(c) reduce to one quarter.
(d) remain the same.

Ans: (b) increase by three times. ✔

Electrical Machines-Transformer MCQ Question 10:-

The transformer exciting current has two components, magnetising component and core-loss component. Neglecting impedance drop

(a) both of them are in phase with the supply voltage.
(b) the former lags the supply voltage by 90° while the latter is in phase with supply voltage.
(c) both of them lag the supply voltage by 90°.
(d) the former is in phase with the supply voltage while the latter lags the supply voltage by 90°.

Ans: (b) the former lags the supply voltage by 90° while the latter is in phase with supply voltage. ✔

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