Voltage regulation is define as

Question

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The per unit change in the sending end voltage magnitude for a specific variation in the receiving end voltage from no load to full load

Explanation: Voltage regulation is a critical parameter for electrical power systems that measures the ability of a system to maintain a constant voltage at the load terminals under varying load conditions. It is defined as the change in the receiving end voltage when the load is disconnected (no load), relative to the voltage at full load, expressed as a per-unit or percentage value of the full load voltage.

Working Principle: As load current increases, the voltage drop across the impedance of the line (resistive and inductive) increases, resulting in a lower receiving end voltage. Voltage regulation quantifies this drop relative to the full load condition, providing an indication of how much the voltage changes from the light load condition to the heavy load condition.

Key Formulas: $	ext{VR} = \frac{|V_{NL}| - |V_{FL}|}{|V_{FL}|} 	imes 100\%$ — Per unit voltage regulation expressed as a percentage.

Key Points: A lower value of voltage regulation is desirable as it indicates better voltage stability.; For short transmission lines, voltage regulation depends on the power factor of the load.; Inductive (lagging) loads lead to positive voltage regulation (voltage drop).; Capacitive (leading) loads can lead to negative voltage regulation (Ferranti effect at light loads).

Advantages: Provides a quick metric for system performance; Helps in sizing compensation equipment like capacitor banks or tap-changing transformers

Disadvantages: Does not account for phase angle variations; Sensitive to variations in load power factor

Applications: Transmission and distribution system design; Transformer performance assessment

Additional Info: Voltage regulation is often confused with voltage drop, but they are conceptually distinct measures of line performance.. Option B and C are incorrect because they misidentify the direction of voltage variation or use improper references for the definition.

Answer: A is correct — Voltage regulation measures the percentage change in the receiving end voltage as the load transitions from no load to full load.

Exam Tip: Always remember that for a leading power factor load, the voltage regulation can be negative, which is a key concept often tested in competitive exams regarding the Ferranti effect.

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