Shape of emf generated by delta connected transformer is not always sinusoidal.

Question

Examoogle · Accepted Answer

Option B: False

Explanation & Concepts:
The EMF generated in a transformer is determined by the input voltage waveform and the magnetic flux within the core. In a delta-connected transformer, the EMF induced in each winding is purely sinusoidal, provided the input supply voltage is sinusoidal.

Working Principle: The EMF induced in the transformer winding follows Faraday's Law, $e = -N \frac{d\phi}{dt}$. Since the flux $\phi$ in the core is linked to the applied voltage $V = V_m \sin(\omega t)$, the flux $\phi = \phi_m \sin(\omega t - 90^\circ)$. Thus, the EMF $e = \omega N \phi_m \cos(\omega t - 90^\circ) = E_m \sin(\omega t)$, which is sinusoidal. The delta connection allows the circulation of third-harmonic currents to suppress core distortion, but it does not change the fundamental sinusoidal nature of the generated EMF.

Key Formulas: $e = N \frac{d\phi}{dt}$ — Faraday\'s Law of Induction; $E_{rms} = 4.44 f N \phi_m$ — EMF Equation of a Transformer

Key Points: Transformer EMF is primarily a function of the supply voltage waveform.; A delta connection provides a path for third-harmonic currents, improving the symmetry of the core flux.; The delta-delta configuration effectively cancels out voltage harmonics in the output line voltage.; Non-sinusoidal behavior in transformers usually arises from saturation or non-linear loads, not the delta connection itself.

Advantages: Eliminates third-harmonic currents from the line; Provides a balanced neutral point in specific configurations

Disadvantages: Circulating currents in delta windings can cause heating; Requires careful protection against fault conditions

Applications: Industrial power distribution; High-voltage transmission substations

Additional Info: Option B is the correct choice because the EMF in a delta-connected transformer remains sinusoidal under normal operating conditions.. If the source voltage contains harmonics, the transformer will reproduce them, but the delta connection acts as a trap for triplen harmonics.

Answer: B is correct — The EMF generated in a delta-connected transformer is sinusoidal, assuming the supply voltage is sinusoidal.

Exam Tip: Always remember: A delta connection does not distort the EMF; it actually helps mitigate flux-related harmonics, maintaining a cleaner waveform.

Examoogle · Answer

Option A: True

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