Research on Lightning Impulse Characteristics of Toroidal Air-Core Reactors Before and After Encapsulation

Toroidal Air-Core Reactors, due to their low magnetic leakage characteristics, hold significant application potential in offshore wind power equipment integration. Consequently, investigating their lightning impulse withstand characteristics constitutes a critical aspect of insulation design. This paper investigates the lightning impulse characteristics of Toroidal Air-Core Reactors before and after encapsulation. First, lightning impulse tests were conducted on an unencapsulated reactor prototype, and its overvoltage characteristics were analyzed. Subsequently, the same prototype was subjected to lightning impulse tests again after being encapsulated, and the corresponding overvoltage characteristics were analyzed. Finally, a comparative analysis of the transient voltage distribution before and after encapsulation was performed to discuss the impact of the encapsulation process. The main conclusions obtained are as follows: encapsulation can improve the voltage distribution of both node-to-ground voltage and inter-coil voltage, making it more uniform; it can also reduce the oscillation frequency of the node-to-ground voltage to a certain extent.