- Shunt Reactor Definition: A shunt reactor is defined as an electrical device used in high voltage power systems to stabilize voltage during load changes.
- Voltage Stabilization: It controls dynamic overvoltage and provides capacitive reactive power compensation in systems above 400kV.
- Impedance Types: Shunt reactors come in gapped core or magnetically shielded air core types to maintain constant impedance and avoid harmonic currents.
- Loss Measurement Methods: Losses are measured at lower voltages for high voltage reactors and scaled up; the bridge method is preferred due to the low power factor.
- Operating Conditions: Must handle continuous voltage without overheating, ensuring it operates within safe temperature limits.
What is Shunt Reactor
A shunt reactor is a piece of electrical equipment used in high voltage power transmission systems to stabilize the voltage during load variations. A traditional shunt reactor has a fixed rating and is either connected to the transmission line all the time or switched in and out depending on the load.
A three phase shunt reactor is generally connected to 400KV or above electrical bus system for capacitive reactive power compensation of the power system and to control dynamic over voltage occurring in the system due to load rejection.
The shunt reactor must handle maximum continuous operating voltage (5% higher for 400kV systems) without exceeding a top spot temperature of 150°C during normal power frequency variations.
The shunt reactor should be of gapped core type or magnetically shielded air core type. Both of these designs help to maintain the impedance of the reactor fixed. The impedance should be maintained at a constant value for avoiding harmonic current generated due to the system over voltage.
Shunt reactors primarily experience core losses during operation. Designs should focus on minimizing these core losses.
Measurement of Losses in Shunt Reactor
Losses of a shunt reactor should be measured at rated voltage and frequency. For high voltage reactors, measure losses at a lower voltage and then scale up by multiplying the loss by the square of the ratio of rated current to the current at the test voltage.
As the power factor of the shunt reactor is very low, loss measurement of shunt reactor by conventional wattmeter is not very reliable, instead of bridge method of measurement may be adopted for better accuracy.
This test can not segregate the losses in various parts of the reactor. To avoid, correction of test result for a reference temperature, it is preferable to take the measurement when the average temperature of the winding becomes equal to the reference temperature.
