Recovery of electromagnetic coils insulation under varying conditions in ADITYA-U tokamak.

• Insulation deterioration of coils under varying weather conditions is investigated and actions were taken to revive machine operation. • Sequence and consequences of fall in the insulation resistance of coils due to moisture condensation is studied. • Different techniques are employed to recover and maintain the insulation resistance of the different coils under high humidity range. Insulation resistance (IR) of electromagnetic (EM) coils show a tremendous variation with the changing weather condition. This effect has a major impact on the operation of the ADITYA-U tokamak operation schedule. The failure of EM coil insulation can lead to terrible failure of the coil system and subsequently, the component and respective power system. Series of circumstances are driven to check their impact on the relative humidity (RH) and simultaneously their effect on the IR of the EM coils has been observed. Different techniques are employed to control the humidity and temperature of the experiment hall to maintain the IR of the different EM coils within the experimental limits. In this paper, different factors have been reviewed which affect and change the IR values of the EM coils. Experience gained during years of operation during insulation strength degradation and its recovery is presented in this work. [ABSTRACT FROM AUTHOR]