For the stable operation of interconnected system, the passive element that can be used a interconnecting elem

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For the stable operation of interconnected system, the passive element that can be used a interconnecting element is

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Option A: Reactor

Explanation & Concepts:
A reactor (inductor) is used as an interconnecting element in power systems to limit short-circuit currents. By providing series impedance, it restricts the fault level and allows for the safe interconnection of systems with different fault ratings.

Working Principle: When two power systems are interconnected, the fault current at the combined bus increases significantly. A series reactor introduces inductive reactance $X_L = 2\pi fL$, which limits the current flow during transient fault conditions without creating excessive power loss, as would be the case with resistors. This maintains the transient stability and limits the duty requirements of circuit breakers.

Key Formulas: $X_L = 2\pi f L$ — Inductive reactance of the reactor; $I_{fault} \approx \frac{V}{X_{reactor}}$ — Current limiting effect during fault

Key Points: Reactors help in localizing faults by preventing the transfer of large fault currents between systems.; They provide negligible voltage drop under normal operating conditions due to low steady-state current flow.; Reactors are preferred over resistors because they do not dissipate real power (active power loss).; They are typically air-cored or oil-immersed depending on the voltage level and current rating.

Advantages: Limits short-circuit currents effectively.; Reduces circuit breaker breaking capacity requirements.; Negligible real power loss ($I^2R \approx 0$).

Disadvantages: Causes a voltage drop across the interconnection.; Requires significant physical space and cooling.; May introduce resonance issues with system capacitance.

Applications: Busbar sectionalizing.; Feeder reactors.; Generator reactors to protect stator windings.

Additional Info: Resistors are unsuitable because they would cause continuous $I^2R$ power loss.. Capacitors are generally used for reactive power compensation, not for limiting short-circuit fault current.

Answer: A is correct — A reactor acts as a high-impedance element during fault conditions to restrict short-circuit current flow while remaining transparent during normal steady-state operation.

Exam Tip: Always remember that in power systems, we prioritize reactive components ($L$ and $C$) over resistive ones ($R$) to minimize $I^2R$ power losses.

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Option B: Resistor

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Option C: Capacitor

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Option D: Resistor and capacitor

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