4 Common Valve Wiring Methods Explained: Simple Guide for Beginners

In industrial automation sites, beginners often struggle with valve wiring: the valve doesn't work after wiring, the control logic doesn't match, or they're confused about selecting the right type for the scenario... Actually, the core logic is very simple: clarify your control requirements first, then choose the corresponding wiring method.

This article breaks down the 4 most commonly used valve wiring methods (2-Wire Reverse Polarity, 3-Wire 2-Point Control, 3-Wire 1-Point Control, 2-Wire Auto Return). It supplements key principle details and comes with an easy-to-understand comparison table, so beginners can quickly grasp and select the right method for their needs.

I. First, Understand 3 Basic Concepts to Avoid Mistakes

Clarify these 3 frequently used terms first for easier understanding later:

• Normally Closed (NC) / Normally Open (NO): The default state of the valve when there's no power or signal — NC valves are closed by default, NO valves are open by default (NC is preferred in industrial scenarios for higher safety);
• Hold Position / Auto-Return: Action after power failure — Hold Position = stays in the current position; Auto-Return = automatically returns to the default state via a spring;
• Trigger Logic: Action rules after the valve receives a signal — On-Off Direct Control = signal on/off corresponds directly to open/close; Secondary Trigger = each power-on toggles the state (open → close → open).

II. Detailed Explanations of 4 Common Wiring Methods

Each method is explained with a "core principle" that combines professionalism and simplicity, using easy-to-relate analogies.

1. 2-Wire Reverse Polarity: "Polarity Switch" with Minimal Wiring

Analogy: Controlling a battery-powered toy car — only 2 power wires are needed, and switching the positive and negative poles changes the direction of movement. The valve's opening and closing are also controlled by switching the polarity of the two wires, no additional control wires required; the valve stays in its current position after power failure.

2. 3-Wire 2-Point Control: "Dual Button Switch" for Precise Independent Control

Analogy: Installing two independent buttons on the valve — there are 3 wires in total (common wire + open valve wire + close valve wire). Pressing the "open valve" button (power on the open valve wire) → the valve opens; pressing the "close valve" button (power on the close valve wire) → the valve closes. When both buttons are released (both wires de-energized), the valve stays in its current position.

3. 3-Wire 1-Point Control: "Single Signal Trigger Switch" with Flexible Logic

This is an easily confused type! There are 3 sub-types based on trigger logic, with the core difference being the "correspondence between signal and action": it has 3 wires in total (power +, power -, trigger control wire), and the core is "single signal triggering".

Analogy: A single-key switch — some turn on when pressed (power on) and off when released (power off); others turn on with one press and off with another press, staying in the current position when released.

3 sub-types: On-Off Direct Control (SW=ON→open, SW=OFF→close); Secondary Trigger Hold Position (first power-on→open, second power-on→close, holds position when de-energized); Auto-Return Optional (jumper to switch between the first two logics).

4. 2-Wire Auto Return: "Emergency Switch" Prioritizing Safety

Analogy: An emergency exit door — only 2 control wires are needed. When powered on, the valve moves to the working position (usually open); the moment power is cut off, the internal spring automatically resets the valve to the safe position (usually closed), prioritizing safety and avoiding fault hazards.

III. Easy-to-Understand Comparison of 4 Wiring Methods

Quickly match your needs with this easy-to-read table: