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For limiting the short circuit┬а current
Reactors are used
Resistors are used
Capacitors are used
Any of above
Reactors are used
Current limiting reactors are inductive coils connected in series with the power system to increase the total series reactance. By increasing the reactance, they reduce the magnitude of fault current during a short-circuit condition, thereby protecting circuit breakers and other equipment.
Current limiting reactors are inductive coils connected in series with the power system to increase the total series reactance. By increasing the reactance, they reduce the magnitude of fault current during a short-circuit condition, thereby protecting circuit breakers and other equipment.
IscтАЛ=jXtotalтАЛVтАЛ тАФ The fault current is inversely proportional to the total reactance in the circuit.
XLтАЛ=2╧АfL тАФ The reactance provided by the inductor, which is directly proportional to frequency and inductance.
During a short-circuit, the system impedance drops significantly, leading to an extremely high fault current. According to Ohm's law, IfтАЛ=ZeqтАЛVтАЛ. By adding a reactor (XLтАЛ) in series, the equivalent impedance ZeqтАЛ increases to R2+(XsystemтАЛ+XLтАЛ)2тАЛ, which effectively limits the short-circuit current to a safe value for the protective switchgear.
Reactors provide high impedance under fault conditions to limit current.
They are typically air-cored to avoid saturation during heavy fault currents.
They are categorized as generator reactors, feeder reactors, or bus-bar reactors based on placement.
Reduces mechanical and thermal stress on equipment during faults.
Allows the use of lower-rated (cheaper) circuit breakers.
Minimizes the spread of disturbances to healthy parts of the system.
Introduces continuous voltage drop under normal operating conditions.
Increases the total reactive power consumption of the system.
Can negatively affect steady-state voltage stability.
Power generating stations
Transmission and distribution substations
Reactors are preferred over resistors because resistors would cause significant real power (I2R) losses during normal operation, whereas reactors cause negligible power dissipation.
Capacitors are generally used for power factor improvement, not for current limiting.
A is correct тАФ Reactors are used to provide the necessary series inductive reactance to limit the magnitude of fault current.
Always remember that series reactors reduce fault current, while shunt reactors are used for capacitive compensation in long EHV lines.