The Difference of Electric Three-way Valve Two-wire System And Three-wire System

In various application scenarios of fan coil units, valves are one of the essential key components. The role of valves in water systems is not limited to controlling the flow and stop of fluids, but also includes improving the automation level of the system, saving energy and reducing consumption, enhancing system safety, and adapting to the needs of different application scenarios, thereby ensuring the safe and efficient operation of the water system.

The control of valves can adopt various transmission methods, such as manual, electric, hydraulic, pneumatic, turbine, electromagnetic, electromagnetic hydraulic, electro-hydraulic, pneumatic hydraulic, spur gear, bevel gear drive, etc; Under the action of pressure, temperature or other forms of sensing signals, the valve can act according to predetermined requirements, or perform simple opening or closing without relying on sensing signals. The valve relies on driving or automatic mechanisms to make the opening and closing parts move up, down, slide, swing or rotate, thereby changing the size of its flow channel area to achieve its control function. This article will explore the differences between the two-wire and three wire systems of electric three-way valves

First, the definition of two and three wires of the electric valve

1. The two wires of the electric valve: the two wires of the electric valve are the control signal input line and the power cord.

2. Three wires of the electric valve: the three wires of the electric valve are respectively the control signal input line, the power line and the feedback signal output line

Advantages of two-wire electric valve:

1. The structure of the two-wire electric valve is simple, without a control circuit, and the hysteresis motor is resistant to humid working environments,

2. Globe valve type electric valves are generally not prone to water hammer phenomenon, and the water flow sound is not obvious when opening and closing the valve.

3 When the actuator malfunctions, it is easy to manually open the valve.

4 When the actuator malfunctions, it is relatively easy to replace and the wiring is also relatively simple.

 Disadvantages of two-line electric valves:

1 The lifespan of a two-wire actuator is entirely dependent on the lifespan of the hysteresis motor, and its lifespan is limited.

2. When the actuator is turned on, it always needs to consume electricity, which is not energy-saving. In addition, when the motor is powered on for a long time, it heats up severely and is easily damaged.

3. When closing the valve, it is completely reset by the valve core spring. If the installation direction is reversed, it cannot be completely closed.

4. The structural design of the globe valve body is limited in flow rate, and there is a large differential pressure between the front and back of the valve, especially for the red flush process valve body currently available on the market, which has a smaller flow rate.

The three wire electric three-way valve requires connecting the power and signal lines to the controller. Among them, the signal line is used to receive control signals from the controller and can achieve feedback function. This wiring method is relatively complex, but it can achieve more control functions and operate more intelligently.

The two-wire three-way valve is simple and easy to install, but it cannot achieve feedback function. The three wire three-way valve is complex and requires connection to a controller, but it can achieve feedback function and has more control functions.

Two wire electric three-way valves are suitable for some simple situations, such as fully open and fully closed control of pipeline valves, or situations that do not require feedback and control. The three wire electric three-way valve is suitable for situations that require more intelligent and refined control, such as monitoring the valve's opening or closing status, outputting signals, and control.