Analyzing Burn Out and Random Trips at Starting: Induction Motors Driving Main Blowers

Two squirrel-cage induction motors rated at 2,984 kW, 6.9 kV, 60 Hz, and 3,556 r/min with a direct start driving a main blower in a blast furnace facility present random trips during starts and also an event of motor burning. These trips interrupt the motor starting by 50 and 46 N function actuations. Considering the risk of motor damage, the consequent interruption of blown air supplied to the furnace, and the risk of human injuries by step or touch voltage, this article presents an analysis of the causes and a proposition for a solution to eliminate these trips.