Turbine Valve Control



Fail Safe Protection, Guaranteed

Demanding applications, such as steam turbine control, require reliable shut down capability in failure situations. Utilizing a closure spring and a unique fail safe electromagnetic (EM) clutch, Diakont fail safe spring EMAs provide 100% guaranteed valve closure during fast-trip scenarios. In the event of a trip command from the control system, loss of communication, or loss of power to both EMA channels, the output shaft will immediately close the valve under the spring’s force. The system automatically reengages within four seconds.

Diakont is a trusted supplier of industry-leading dual-redundant and fail safe electromechanical actuators (EMAs) and control systems for the energy industry. Diakont EMA solutions allow customers to replace hydro-mechanical motion control systems with electro-hydraulic or fully electric solutions for valve control. Diakont EMAs incorporate progressive technology, including precisely machined roller screws and high-force permanent magnet synchronous motors (PMSM). These components are integrated into a single unit, thus providing exceptional performance in a compact footprint. Diakont actuators and turbine control systems have improved plant performance by providing greater responsiveness, safety, and stability, as well as more precise control and reduced maintenance challenges.

Peerless Performance in Steam Turbine Applications

Diakont has successfully upgraded dozens of steam turbine control systems that incorporated dual-redundant EMAs, leading to impressive results. Diakont’s steam valve control systems have been shown to reduce the variance of full-load backpressure from ±4.25 PSI to ±0.5 PSI, increasing power output by 2.0 MWe per reactor with no corresponding change in thermal power output. Plus, Diakont actuators are able to complete a full linear stroke in less than 50 ms, which increases turbine safety and overspeed protection.

Common applications:

  • Direct steam pilot valve actuation
  • Steam turbine control systems
  • Fuel control valve actuation


Pilot valve control actuator

Steam valve actuator

Rated force

675 - 2250 lbf (3 - 10 kN)

4500 lbf (20 kN)

14500 lbf (65 kN)


2 in (75 mm)

Up to 5.9 in (Up to 150 mm)

Up to 10 in (Up to 250 mm)

Motion time for full stroke (from motor)

0.3 - 0.5 sec

0.9 - 3 sec

Motion time for full stroke (from spring)

Under request

0.3 - 0.4 sec


every 2 -4 years


20 years

Protection degree


Hazard location standard

Optional: ATEX Zone 2

Mounting options Trunnion, rear clevis, front flange, custom mounting

Fail safe options

• Fail-safe spring and internal electromagnetic clutch

• Redundant motor and feedback sensor

• Manual over-ride hand wheel

• Brake