Question
What is the current that flows in the primary winding of a transformer when there is no load on the secondary winding?
Answer Options
- A) Stabilizing current
- B) Direct current
- C) Excitation current
- D) Magnetizing current
Correct Answer: D
Explanation
In an ideal transformer, no current would flow in the primary if the secondary winding were open-circuited. However, in a real-world transformer, a small current must flow in the primary winding even when there is no load on the secondary. This current is necessary to establish the oscillating magnetic flux within the core.
This small current is called the Magnetizing current (or sometimes the excitation current). It is the minimum current required to create and sustain the magnetic field that links the primary and secondary windings. This current is primarily reactive, meaning it lags the applied voltage by nearly 90 degrees and contributes very little to the real power dissipation of the primary winding.
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