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Which of the device is employed in substation to limit the short circuit current in the power system
Shunt condenser
Reactor
Series capacitor
Shunt capacitor
Reactor
A current-limiting reactor is an inductive coil installed in a substation to increase the circuit impedance during fault conditions. By increasing the impedance, it significantly reduces the magnitude of the prospective short-circuit current, thereby protecting switchgear and equipment from high thermal and mechanical stresses.
A current-limiting reactor is an inductive coil installed in a substation to increase the circuit impedance during fault conditions. By increasing the impedance, it significantly reduces the magnitude of the prospective short-circuit current, thereby protecting switchgear and equipment from high thermal and mechanical stresses.
XLтАЛ=2╧АfL тАФ Reactance of the reactor
IscтАЛ=ZeqтАЛVтАЛ тАФ Short circuit current relationship
The reactor provides a high series reactance (XLтАЛ=2╧АfL) which acts as a bottleneck for current during a fault. Because the fault current is inversely proportional to the total impedance of the system (IfтАЛ=V/ZtotalтАЛ), adding a reactor increases ZtotalтАЛ, consequently forcing the short-circuit current to a manageable level.
Reactors are generally classified as Air-cored or Iron-cored.
They are placed in series with the lines to limit fault current to the capacity of the circuit breakers.
They are widely used in busbar coupling or as feeder reactors.
The power loss in a reactor is very low because it is purely inductive.
Reduces mechanical stress on equipment during faults
Allows the use of circuit breakers with lower breaking capacity
Minimizes damage to healthy sections of the power system
Causes a constant voltage drop under normal operating conditions
Reduces the transient stability of the system
Increases the reactive power demand of the system
Busbar sectioning in large substations
Feeder protection
Generator current limiting
Shunt capacitors are used for power factor improvement, not current limiting.
Series capacitors are used for voltage regulation and stability improvement by canceling out transmission line reactance.
B is correct тАФ A reactor is an inductor designed to limit the magnitude of short-circuit current in a power system.
Always remember that reactors limit fault current while capacitors (series) are used for compensating line reactance to enhance power transfer capacity.