The ABB SPHSS13​ is a specialized Hydraulic Servo Module designed for integration within ABB’s Symphony™ and Advant distributed control systems, particularly for power generation and heavy industrial applications. It functions as the critical interface between the digital control system and high-power hydraulic actuators, converting low-power analog or digital command signals (e.g., 4-20mA) from the DCS into the high-current drive signals required to precisely position electro-hydraulic servo valves (EHSV) or proportional valves. This enables accurate, fast, and reliable control of turbine inlet valves, steam admission valves, or other critical hydraulic machinery.

In a large steam turbine power plant, the main steam admission valve controls the flow of high-pressure steam to the turbine, directly determining power output. Precise, rapid valve positioning is essential for load control, frequency regulation, and safety. The DCS calculates the required valve position setpoint. The ABB SPHSS13​ Hydraulic Servo Module, installed in the turbine control cabinet, receives this command. It amplifies the signal and drives the torque motor of the electro-hydraulic servo valve. The EHSV then ports high-pressure hydraulic oil to the valve’s actuator, moving it to the exact demanded position. A Linear Variable Differential Transformer (LVDT) on the actuator stem provides real-time position feedback to the SPHSS13, which closes the loop locally for stable, jitter-free control. The SPHSS13​ solves the critical pain point of interfacing sensitive electronic control systems with high-power hydraulic systems, providing the necessary power amplification, signal conditioning, and closed-loop stability for mission-critical motion control.