Substation transformers have cover-mounted, primary and secondary bushings and can be provided with load tap changers (LTC). They are generally connected directly to overhead utility power lines. ABB’s proven design offers excellent mechanical strength that has been proven through years of service and special testing. ABB uses a MicaFil low frequency heating insulation drying process where the insulation is dried in its own tank and is never exposed to the atmosphere once it dries.