The three-phase dry-type air-core shunt reactor bank is Y-connected with isolated neutral point. The three-phase voltages to ground and phase current measured by potential transformer (PT) and current transformer (CT) cannot accurately calculate the electrical parameters of each reactor

and the variation of electrical parameters during the progression of inter-turn short circuit fault is also uncertain

so it is difficult to effectively implement online monitoring for inter-turn short circuit faults. To solve these problems

this paper establishes the basic equations of the shunt reactor bank based on the relative deviation of reactance and the absolute deviation of loss percentage. A new monitoring method is proposed

and the actual reactor inter-turn short circuit development process test and on-line monitoring research are carried out in this paper. The results show that the neutral voltage is composed of zero sequence voltage

and voltage sag caused by unbalanced three-phase reactance and loss percentage

respectively. Using the basic equation of the normal operation reactor banks to analyze the impedance of the fault reactor produces an inherent deviation

which can be eliminated through approximate calculation. During the development of inter-turn short circuit fault

the values that including the relative variation of current

the relative variation of reactance and the absolute variation of loss percentage show an overall trend of increasing gradually. The absolute variation of loss percentage is the largest in the early stage of fault

which reaches the order of 1%. It is easier to identify the inter-turn short circuit fault by monitoring the absolute variation of loss percentage

and the effective monitoring results are obtained in practical applications.