Hua Heng HY-3500 Steam Turbine Safety Monitoring and Integrated Protection System The HY-3500 steam turbine monitoring and protection device is a highly reliable combined multifunctional monitoring instrument. This protective device is an essential monitoring tool for the operation of the steam turbine. It mainly consists of monitoring modules for vibration, speed/overspeed, axial displacement, differential expansion, eccentricity/swing, thermal expansion, hydraulic engine,