Across the power generation industry, operators are under increasing pressure to do more with less. Aging assets are being pushed to operate longer; maintenance windows are shrinking, and expectations for availability and safety are rising. With capital budgets under pressure, plant owners are looking closely at modernization opportunities that deliver measurable reliability improvements without adding complexity.
With life extensions and longer operation windows, one area drawing renewed attention is turbine valve control. Traditional hydraulic actuator systems have been widely used for decades, but many plants are now seeing the operational tradeoffs more clearly, especially as equipment ages and experienced labor becomes harder to find.
To help address these challenges, Siemens Energy developed the Omnivise iSER® Actuator (Intelligent Self-Contained Electrohydraulic Redundant Actuator). iSER actuators are designed to precisely control steam admission valves for power generation turbines and can be applied to other positioning, holding, and trip applications.
Omnivise iSER® Actuator’ Key Advantages:
- iSER actuators are self-contained electrohydraulic turbine valve actuators designed for power generation.
- The design eliminates the need for external electro-hydraulic (EH) skids and high-pressure hydraulic piping.
- Built-in redundancy helps eliminate single-point vulnerabilities and supports reliable operation.
- Digital controls and onboard sensors support condition monitoring and predictive maintenance.
- iSER actuators integrate with modern plant systems using ethernet-based communications.
Rethinking Traditional Hydraulic Actuation
Conventional hydraulic systems rely on centralized EH skids with large reservoirs, extensive high-pressure piping, and common trip systems. While proven, these designs can introduce single-point vulnerabilities and require ongoing effort to manage leaks, contamination, fluid degradation, and component wear. For many plants, especially those pursuing upgrades or life-extension projects, the cost and downtime associated with these systems can be substantial.
With iSER, the entire hydraulic system is integrated into the actuator. This removes several common sources of installation and maintenance complexity:
- No external hydraulic power unit (HPU) required
- No turbine-deck high-pressure piping runs
- No large, hazardous oil inventory to manage
- Fewer connections and leak points
Each actuator operates as a closed, self-contained system, dramatically simplifying design, installation, and long-term operation.
How the iSER Actuator Works: Intelligent Performance
The iSER actuator is a double-acting electrohydraulic actuator assembly. Motors and pumps generate hydraulic pressure on either side of the piston, allowing controlled valve movement. Once the actuator reaches the desired position, check valves maintain the pressure required to hold the piston in place, and the motors turn off.
For precise closed-loop control, iSER uses Linear Variable Differential Transformers (LVDTs) for position feedback. This supports:
- Accurate positioning for modulating control
- Stable holding at set-point
Additionally, LVDTs are available in duplex or triplex configurations. This closed-loop control enables near-infinite positioning resolution, making the iSER actuator well-suited for both modulating and non-modulating applications across a wide range of turbine sizes.
Built-In Redundancy for Mission-Critical Reliability
Reliability is paramount in power generation. A failure that prevents proper valve positioning—or prevents a valve from closing during a trip event—can create safety risk, and lead to unplanned downtime. The iSER actuator is designed with redundancy to reduce these risks. With the iSER actuator, if one motor or pump fails, the actuator continues to operate.
Standard redundant components can include:
- Motors and pumps
- LVDTs
- Trip solenoids
These redundant pumps, motors, LVDTs, and trip solenoids help remove single-point vulnerabilities that can compromise turbine operation. In an emergency, the actuator includes a modular and online testable trip system. This smart design ensures both personnel safety and turbine protection, even under fault conditions.
Lower Costs Across the Lifecycle
Beyond performance and reliability, one of the iSER actuators’ most compelling advantages is its impact on total cost of ownership. By eliminating centralized HPUs and high-pressure piping required for an EHC upgrade, installation costs and schedules can be reduced significantly, often delivering up to a 40 percent overall cost reduction compared to traditional hydraulic systems.
The self-contained design also minimizes oil usage, typically requiring less than one gallon of hydraulic fluid per actuator. This greatly reduces the risk of oil leaks, lowers environmental exposure, and simplifies maintenance procedures. Integrated sensors and digital controls enable condition monitoring and predictive maintenance strategies, shifting plant teams away from reactive repairs toward more efficient, planned interventions.
Flexible, Scalable, and Future-Ready
Every power plant has unique requirements, and the iSER actuator’s modular design allows it to be tailored to specific applications. Power output can be scaled to suit small or large steam turbines, and configuration options (such as simplex, duplex, or triplex components) provide flexibility to meet varying operational and safety requirements.
Equally important, the actuator integrates easily with modern plant control systems using standard industrial ethernet-based communication protocols such as Profinet or Modbus TCP. This ensures seamless connectivity to distributed control systems (DCS) and supports broader digitalization initiatives within the plant.
Advancing Turbine Control for a Changing Energy Market
As the energy landscape evolves, turbine owners and operators need solutions that improve reliability without creating new maintenance burdens. Operators must modernize critical systems to remain reliable, flexible, and cost-effective. Modernization projects often succeed or fail based on how much work must be performed around the turbine deck.
With the Omnivise iSER actuator, Siemens Energy offers a proven, forward-looking solution that redefines hydraulic turbine control. By combining intelligent control, self-contained hydraulics, and robust redundancy, the iSER actuator delivers the reliability and precision today’s power generators demand, while reducing complexity, cost, and risk for the future.
Ready your plant for tomorrow. Learn more about Siemens Energy iSER Actuators today.
Read the iSER Actuators whitepaper.
