Which of the following plays a vital role in the determination of sending end and receiving end voltage in rin

Question

Which of the following plays a vital role in the determination of sending end and receiving end voltage in ring main AC distribution scheme?

Examoogle · Accepted Answer

The correct answer is Option D: Power factor. In a ring main AC distribution system, the voltage drop is significantly influenced by the power factor of the load. Because the line impedance is a complex quantity ($Z = R + jX$), the phase angle of the current relative to the voltage determines whether the drop is primarily resistive or reactive.

Step-by-Step Solution & Concepts:
In a ring main AC distribution system, the voltage drop is significantly influenced by the power factor of the load. Because the line impedance is a complex quantity ($Z = R + jX$), the phase angle of the current relative to the voltage determines whether the drop is primarily resistive or reactive.

Working Principle: The voltage drop $\Delta V$ in a distribution line is given by $I(R \cos \phi \pm X \sin \phi)$. Since $\cos \phi$ is the power factor, it dictates the magnitude and sign of the voltage regulation. A lagging power factor increases the voltage drop, while a leading power factor can actually cause a voltage rise at the receiving end.

Key Formulas: $\Delta V \approx I(R \cos \phi + X \sin \phi)$ — approximate voltage drop; $V_{S} = V_{R} + I(R + jX)$ — vector relation between sending and receiving end

Key Points: Voltage regulation is directly dependent on the load power factor ($\cos \phi$).; In a ring main, current distribution depends on the impedance of the branches and the power factor of the loads connected at various points.; A low lagging power factor leads to higher current for the same real power, increasing ohmic losses and voltage drop.

Advantages: Improved voltage profile compared to radial systems; High reliability as supply can be maintained from either direction

Disadvantages: Complex fault analysis and protection coordination; Difficulty in maintaining uniform voltage if load power factors vary significantly across the loop

Applications: Urban power distribution networks; Industrial plant power distribution

Additional Info: Eddy current and hysteresis losses are associated with transformers and machines, not voltage drop in distribution lines.. Breakdown voltage of oil is a dielectric property, not a factor in network voltage drop.

Answer: D is correct — The load power factor determines the voltage drop across line impedance ($R + jX$) in an AC distribution circuit.

Exam Tip: Always remember that in AC systems, the reactive component of the line ($X_L$) interacts with the power factor ($\cos \phi$) to either assist or oppose the voltage drop.

Examoogle · Answer

Option A: Eddy current loss

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Option B: Hysteresis loss

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Option C: Breakdown voltage of a distribution transformer oil

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