In order to improve the safe reliability of shunt capacitor devices

some units like to enlarge the reserved capacity

such as increasing the rated voltage of capacitor

when they choose equipment. These actions will not only lead to the loss of reactive compensation

but also magnify some harmonic possibly

even cause harmonic resonance which endangers the normal operation of network. This paper introduces the possible consequences if the shunt capacitor and series reactor didn’t be selected properly and concludes the choice principle of the shunt capacitor and series reactor. The points for attention are also given.