What is the difference between two-wire, three wire, and analog control for electric ball valves? First look at the functions, then look at the number of lines

Two wire, three wire, or analog signals correspond to the control function first, and then correspond to the wiring. Customers should clearly state the switch or adjustment tasks, main power supply, and feedback requirements separately; The same number of wires does not mean that two electric actuators can be interchanged.

The main power supply and control commands are two separate things

Some actuators use power switching to achieve switching, some require continuous power supply and accept independent switch contacts, and some have integrated control modules. The same number of lines may represent different circuits, and AC and DC configurations cannot be applied to each other. The control method should be defined by the technical data of the specification and cannot be judged based on color or another brand's schematic diagram. Electrical implementation must be completed by qualified personnel according to the finished product documents.

The switch command is not equal to the continuous position command

The switch type mainly requires reaching the on or off position, while the regulating type requires continuous control according to the target valve position. Analog input is only valid when the actuator has corresponding modules and control functions, and the ordinary motor power supply terminal does not become a 4–20mA interface as a result. Being able to stop in the middle position does not necessarily mean that the valve body is suitable for long-term throttling; The control function needs to be compared separately with the applicability of the ball core, valve seat, and pressure difference.

Valve position feedback may not necessarily be included in the basic line count

Open position and close position contacts, continuous position feedback, and communication status belong to different types of information. If the control system needs to determine the completion of an action, it should specify the feedback form and detection position, rather than just requiring a three wire electric valve. The input signal represents the desired action, and the feedback represents the detection result. Even if they have the same range, they cannot be connected to each other or treated as the same loop. The procurement documents should be listed separately.

Write down the power loss, signal loss, and local remote status clearly

The loss of main power and control signal of the actuator may result in different outcomes. When ordinary electric drives do not have energy storage or other fail safe structures, they cannot default to power failure and continue to shut down. Switching permissions locally/remotely, and maintaining or resetting logic also need to be compatible with device control. When selecting interfaces, provide power supply, instructions, feedback, fault requirements, and on-site environment; The terminal function and specific wiring are determined by the supply diagram, and cannot be judged solely based on the names of two or three wires.

Comparison of selection information

Corresponding products and selection entrance

Writing the requirements as "power+control instructions+feedback+fault action" is more accurate than using two or three wires to represent them. After the interface is clear, matching the ball valve load and operating conditions can reduce the understanding deviation in equipment integration.

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