Which type of surge arrestor is used in a distribution box panel?

Surge protectors (Surge Protective Devices, SPD) installed in distribution board panels are primarily used to protect electrical equipment from transient voltages (surges or spikes) caused by lightning strikes, power grid fluctuations, or other factors. Depending on the application and protection requirements, the types of surge protectors commonly used in distribution board panels include the following:

1. Type 1 Surge Protector (Primary Protection at Power Entry)

Application: Installed at the main distribution board or power entry point of a building to protect the entire electrical system from external surges, such as those caused by lightning traveling through power lines.

Features:

• Suitable for protecting against high-voltage surges, capable of withstanding significant current impacts (e.g., 40kA or more for an 8/20 microsecond waveform).

• Typically connected to the building's grounding system, providing robust surge diversion.

•  Primarily used for first-level protection to prevent external surges from entering the building.

2. Type 2 Surge Protector (Distribution Board Level Protection)

Application: Installed within the distribution boards inside a building to protect downstream electrical equipment and circuits. This is the most common type of surge protector found in distribution board panels.

Features:

• Suitable for medium-intensity surge protection, typically capable of withstanding 10-40kA of current impact (8/20 microsecond waveform).

• Provides second-level protection, mainly addressing internal surges generated within the building, such as those caused by switching operations or motor startups.

• Usually installed next to circuit breakers or integrated within the distribution board, making maintenance and replacement convenient.

3. Type 3 Surge Protector (End-Device Level Protection)

Application: Installed near terminal devices (such as computers, servers, home appliances) to provide the last line of defense against surges, protecting sensitive electronic equipment.

Features:

•  Suitable for low-intensity surge protection, typically capable of withstanding 5-10kA of current impact (8/20 microsecond waveform).

•  Provides third-level protection, specifically designed to safeguard devices that are highly sensitive to voltage fluctuations, such as communication equipment, medical devices, and precision instruments.

• Common forms include surge-protected power strips and socket-type surge protectors.

4. Combination-Type Surge Protector

Application: Combines the functions of Type 1 and Type 2 surge protectors, suitable for environments requiring both external and internal surge protection.

Features:

• Offers strong surge diversion capabilities and a wide protection range, protecting against both external and internal surges.

• Commonly used in critical facilities or applications with high surge protection requirements, such as data centers, hospitals, and industrial plants.

5. Modular Surge Protector

Application: Widely used in various distribution boards, especially in commercial and industrial settings, for ease of installation and maintenance.

Features:

• Modular design allows each module to function independently; if one module fails, only that module needs to be replaced without affecting the others.

• Often comes with indicator lights or alarm functions to monitor the surge protector's status in real-time and alert users when a module needs replacement.

6. Single-Phase and Three-Phase Surge Protectors

• Single-Phase Surge Protector: Suitable for single-phase power systems (e.g., residential homes, small offices), used to protect 220V/230V electrical equipment.

• Three-Phase Surge Protector: Suitable for three-phase power systems (e.g., factories, commercial buildings, large office complexes), used to protect 380V/400V electrical equipment.

Considerations for Selecting a Surge Protector

When choosing a surge protector for a distribution board panel, consider the following factors:

• Installation Location: Whether it will be installed at the main distribution board, branch distribution board, or near terminal devices.

• Protection Level: Choose the appropriate protection level based on the source and intensity of the surges (Type 1, Type 2, Type 3, etc.).

• Rated Discharge Current (In): The maximum current impact the surge protector can handle, measured in kA. Select a suitable rated discharge current based on the actual application environment.

• Maximum Continuous Operating Voltage (Uc): The highest voltage the surge protector can withstand over time, which should be higher than the system's nominal voltage.

• Response Time: The speed at which the surge protector reacts to a surge; faster response times are better to ensure timely protection of equipment.

• Failure Alarm Function: Some surge protectors come with indicator lights or alarms to signal when the device has failed, facilitating timely replacement.

Summary

For distribution board panels, the most common type of surge protector is the Type 2 surge protector, which effectively protects downstream electrical equipment from internal surges. If the building is located in an area with frequent lightning activity, it is advisable to install a Type 1 surge protector at the main distribution board and add Type 3 surge protectors near critical devices to create a multi-layered protection system. Additionally, modular surge protectors are often preferred in commercial and industrial environments due to their ease of maintenance and replacement.