Induction Sensor

Knowing when the bearings in Hydro-Electric turbines are wearing out is critical for balancing maintenance with plant down-time. Therefore, the goal of this project was to devise a system that could be placed in the cooling loop of the turbine lubrication oil that would constantly monitor for signs of wear. Because the bearings in these turbines are made of Babbitt, a non-ferrous alloy of mainly Tin, there were no off-the-shelf magnetic detection systems to look for worn particles in the oil. My senior design team and I spent 9 months working out the math, circuitry, and mechanics to create a detection system that would work on this material, with efficacy on a small enough scale to catch wear before it became critical. The device shown here is a prototype dual induction sensor. The system sweeps a series of signals through the top coil of the two-coil system, monitoring the induced voltage in the second coil. This allows the system to find the resonant frequency of the system in it's neutral state, which is when only lubrication oil is in the core of the coils. If an amount of Babbitt as small as 5 mg flows through the core, it affects the flow of magnetic energy from the first coil into the induced coil, and creating a significant decrease in the output voltage. This means that the system can catch signs of wear as soon as they begin.