The ULD-40 is an ultrasonic detector designed for corona and arcing inspections for predictive maintenance in electric utilities. Corona effect occurs when electricity is discharges into the surrounding atmosphere form a high voltage source. Corona effects and electrical arcs in the air emit ultrasounds. The role of the ULD-40 consists of capturing emitted ultrasounds and of translating them into the audible range. This equipment is perfect for high voltage maintenance program.