How does an electric control valve achieve fail-safe shutdown?

When the power is lost, the electric control valve can only be operated manually. Whether it is angular or linear motion, a motor is required, and it needs to be powered in order to reach the desired position. After the signal is lost, automatic switching on or off can be achieved through the corresponding settings (standard instrument control). Or, a program can be added to the DCS or PLC to control it so that it reaches the desired position and state. Pneumatic control valves can easily meet the requirements you mentioned. When selecting a control valve, attention should be paid to the direct and reverse action. Select according to the process requirements.

The so-called fault shutdown refers to the ability of the valve to close on its own in the event of a power loss or air loss. However, for the fault shutdown function of electric valves, it seems that there is either a spring or some kind of emergency mechanical mechanism; in the event that the motor loses power, it can no longer rotate. So... fault shutdown, fault operation, and fault hold are all inherent properties of the valve, and it seems impossible to change them on one’s own... This is just my personal opinion, as I haven’t used electric valves very often.

An electric valve generally cannot achieve fault shutdown in the absence of power, but it can do so in the absence of a signal.

1. The electric device is equipped with a high-energy power source built into it. Under normal conditions, the energy for the actuator is supplied by the power grid; in case of accidents or emergencies, the energy comes from a power source built into the actuator itself. There are manufacturers that offer such products.

The motor is broken, so the built-in UPS is useless too, right?

Yes, the motor can’t break down! I just asked the manufacturer – there is a capacitor inside the actuator (an imported one), which allows the valve to automatically return to a safe position, either closed or open, when power is lost. , (Solenoid valve is fine, with a return spring)! ---“How does an electric control valve ensure that it can automatically return to a safe closed or open position in the event of a loss of power or signal?

Electric valves – our company manufactures them: power-off reset actuators that allow it to be set whether the valve should remain open or closed in the event of a power loss. Product Overview: Electric actuators are used to control valves that can rotate within a range of 0°–300°, as well as other similar devices such as butterfly valves, ball valves, dampers, plug valves, and louver valves. They are powered by AC voltages of 24V, 110V, 220V, 380V, and 415V, as well as DC voltages of 12V, 24V, and 220V. In addition, the actuators can have their own power source (with a reset function), and they use 4–20mA current signals or 0–10VDC voltage signals as control signals to move the valve to the desired position, thereby enabling automated control. It can be widely applied in fields such as petroleum, chemicals, power generation, metallurgy, pharmaceuticals, papermaking, energy, water treatment, shipbuilding, textiles, food processing, and building automation. At the same time, it boasts many advantages such as small size, light weight, elegant design, unique structure, compactness, fast opening and closing, easy installation, low operating torque, convenient operation, digital display of valve position, no need for maintenance, and safe and easy use. II. Performance Features
● Small and lightweight, easy to assemble, disassemble, and maintain; can be installed in any location.
● Simple and compact structure; enables rapid 90° rotation for opening and closing.
● Low operating torque, requiring less effort for operation.
● Flow characteristics are nearly linear, resulting in good regulation performance.
● Multiple control signals available: on/off control.
● Proportional (regulating) control: 0-10VDC or 4-20mA.
● Feedback outputs include 4-20mA, auxiliary switch, and feedback potentiometer (0-1K).
● Control circuit options: Type A, B, C, D, E, F, H.
● Battery capacity: 2Ah.
● Operating temperature range: -20°C to +60°C.
● Protection rating up to IP68 (optional).
● The actuator remains powered and has a power-off reset function, with three options: reset to open, reset to closed, or no reset; the setting can be chosen at the time of manufacturing.

III. Special Features
In case of sudden emergencies during use, when the external power supply is disconnected, the power-off reset series of electric actuators can immediately send a command to the valve, allowing it to continue operating until it reaches the fully open or fully closed position, thereby achieving a power-off reset effect. The valve can be set to fully open or fully closed upon power loss, as per requirements. This feature meets the protection needs of various special pipelines, and these actuators are widely used in power plants, chemical plants, environmental protection equipment, and other applications.

If it’s about setting mail delivery to on/off/hold, that is achievable. If loss of power requires on/off/hold functions, some actuators can also achieve this. If it’s the motor of the electric actuator that’s broken, even a god might not be able to fix it. . .

Noah and Betis both have spring-return actuators; when the power is cut, the brakes are released, allowing them to reach a disabled position. However, the torque generated in these systems isn’t very high. Bernard also has such actuators. Some manufacturers add UPS batteries to achieve this functionality, but personally I think pneumatic systems are the best choice, with hydraulic systems as a fallback option