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Series reactors are used to
Improve the transmission efficiency
Improve the power factor of power system
Improve the voltage regulation
Bring down the fault level within the capacity of switchgear
Bring down the fault level within the capacity of switchgear
Series reactors are inductor coils connected in series with the power lines to limit the short-circuit current during a fault. By adding inductive impedance to the circuit, they ensure that the fault current remains within the interrupting capacity rating of the associated circuit breakers and switchgear.
Series reactors are inductor coils connected in series with the power lines to limit the short-circuit current during a fault. By adding inductive impedance to the circuit, they ensure that the fault current remains within the interrupting capacity rating of the associated circuit breakers and switchgear.
IfтАЛ=XtotalтАЛVphтАЛтАЛ тАФ Relationship showing how total reactance limits the fault current
XLтАЛ=2╧АfL тАФ Definition of inductive reactance provided by the reactor
When a short-circuit fault occurs, the system impedance is drastically reduced, causing massive current flow. A series reactor introduces an additional reactance XLтАЛ=2╧АfL in series with the source, which increases the total impedance of the fault path. Consequently, according to Ohm's law (IfaultтАЛ=ZtotalтАЛVтАЛ), the magnitude of the fault current is reduced to a safe level.
Series reactors provide a high impedance path during fault conditions.
They are typically located at the generator terminals, bus-bar sections, or feeder lines.
They must be designed to withstand the thermal and mechanical stresses of high short-circuit currents.
The use of reactors results in a small voltage drop during normal load conditions.
Reduces the cost of circuit breakers by lowering required MVA rating.
Protects equipment from mechanical stress caused by high magnetic forces during faults.
Limits damage at the point of fault.
Causes a constant voltage drop even during normal operation.
Contributes to power loss due to I2R losses in the reactor winding.
May decrease steady-state stability of the system.
Generator bus-bars
Feeder circuit protection
Bus-bar sectionalization
Reactor rating is generally expressed in terms of % reactance on a specified MVA base.
Option B (Power factor improvement) is typically handled by shunt capacitors, not series reactors.
Option C (Voltage regulation) is usually managed by tap-changing transformers or shunt compensators.
D is correct тАФ Series reactors increase the total impedance of a power system, thereby limiting short-circuit current to values within the interrupting rating of circuit breakers.
Remember that series reactors are for fault current limitation, while shunt reactors are for voltage control (compensation of Ferranti effect in long transmission lines).