The differences between two-port and one-port SPDs in SPD communication wiring lie in their structure and surge protection methods. These differences significantly impact wiring methods, signal quality, protection performance, and installation objectives.

1-port SPD

• This is a method of directly protecting the signal line with the same contact point (or parallel/bypass) for input and output.

• When a surge occurs, the energy is immediately dissipated between the signal line and ground, and SPDs are connected in parallel in front of the device to protect the entire incoming signal.

• The wiring is simple and can be easily attached to existing systems.

• Little variation in signal quality.

• It requires little installation space and is easy to maintain.

2-port SPD

• Input and output are completely isolated, with signal lines “running in series” inside the SPD.

• The surge absorption/filtering capability inside the SPD makes it more effective at filtering out noise/surge/high frequency interference from passing signals.

• When a surge event occurs, the SPD absorbs energy at the input port and transmits only the pure signal to the output port.

• Suitable for applications requiring signal quality preservation and high-speed data security in advanced communication networks (Ethernet, signal lines, data lines, etc.).

• It has strengths in wavelength separation, noise, and common mode/differential mode surge protection.

Comparative Summary

The 2-port mode is suitable for high-end communication lines, sensitive signals, and data transmission, while the 1-port mode is mainly used for general signals/low-speed communications and simple field installations.