Surge Protection Device VS Surge Protector VS Surge Arrester

Terms such as “surge protection device (SPD),” “surge protector,” and “surge arrester” are often used interchangeably in the market, causing confusion for users when selecting a device.

This article will delve into the differences and connections between these three terms and provide a detailed selection guide to help you choose the most suitable “surge protector” for your application scenario.

Although all three terms aim to provide surge protection, they have subtle but crucial differences in technical definitions, application scenarios, and standard specifications.

This is a standard and professional term, originating from International Electrotechnical Commission (IEC) standards (such as IEC 61643-11). It is a complete category of products conforming to specific standards, referring to electrical devices used to limit transient overvoltages and discharge inrush currents, which must contain at least one nonlinear element.

Characteristics: SPD is an engineering term emphasizing its compliance with international standards and having clearly defined performance parameters (such as Up, In, Iimp, etc.). It is a standard term used in electrical engineering design.

This is a more colloquial and commercial term, especially widely used in the North American market. It typically refers to end-device level protection products, most commonly power strips with multi-outlet sockets.

Characteristics: It belongs to the SPD (Supply, Protection, and Distribution) category, but usually refers to products with lower protection levels (such as Type 3). This term is more focused on the consumer market and mass communication.

This is a traditional and specific term, originally used primarily in power transmission and distribution systems, such as protecting substations and overhead lines from direct lightning strikes or induced lightning overvoltages. In the low-voltage field, it sometimes specifically refers to Type 1 SPDs, which are protective devices capable of withstanding a portion of direct lightning current with a strong discharge capability.

Features: Emphasizes its powerful discharge capability to cope with the most severe lightning current surges. In modern building surge protection systems, it is considered a high-level type of SPD.

Summary of relationships: Conceptually, SPD is a general term encompassing all standard-compliant surge protection products. Surge Protector is typically a subset of SPDs used in the consumer market, while Surge Arrester can be considered a specific type of SPD for high-voltage or high-intensity applications.

Surge Protection Device (SPD): Surge protector (the most standard Chinese engineering term)

Surge Protector: Surge protector / Surge protection socket (more colloquial and commercial)

Surge Arrester: Surge discharger / Lightning arrester (traditional electrical engineering term)

SPD (Type 1/2): Installed at critical nodes in the power distribution system, such as the building’s main distribution cabinet or floor distribution boxes.

Surge Protector (Type 3): Installed at the front end of the device, directly plugged into a wall socket, providing fine protection for terminal devices (such as computers and televisions).

Surge Arrester (Type 1): Installed at the service entry point, i.e., the main distribution cabinet, as the first line of defense.

SPD: Covers all levels (Type 1, 2, 3), providing comprehensive, tiered protection.

Surge Protector: Typically represents Type 3, providing ultimate lean protection.

Surge Arrester: Typically represents Type 1, providing the highest level of coarse protection.

SPD (Type 1/2): Fast response speed (nanosecond level), using technologies such as varistors (MOV) or gas discharge tubes (GDT).

Surge Protector (Type 3): Also fast response speed, but with smaller current capacity.

Surge Arrester (Type 1): Can withstand huge lightning current surges, typically using spark gap technology.

Surge Arrester (Type 1 SPD): Highest (up to 100kA or more, 10/350µs waveform).

SPD (Type 2): Medium (typically 20kA – 80kA, 8/20µs waveform).

Surge Protector (Type 3): Lowest (typically below 20kA, 8/20µs waveform).

Type 1 SPD / Arrester: Typically uses a spark gap, offering high current carrying capacity and arc extinguishing capability.

Type 2 SPD: Typically uses a varistor (MOV), or a combination of MOV and GDT.

Type 3 SPD / Protector: Typically uses an MOV or avalanche diode.

Surge Arrester / Type 1 SPD: Power distribution system at the main power supply line of a building and in high-risk lightning areas.

SPD (Type 2): Distribution boxes, industrial control cabinets, and communication equipment rooms within buildings.

Surge Protector (Type 3): Sensitive electronic devices in homes and offices, such as computers, stereos, smart TVs, and routers.

A robust surge protection system should employ a tiered (or “cooperative”) strategy.

Objective: To discharge large direct lightning strikes or induced lightning currents (10/350µs waveform).

Installation Location: Main distribution cabinet.

Key Parameters: Iimp (Impulse Current).

Objective: To further limit residual overvoltage after Type 1 SPD and handle surges caused by switching operations, etc.

Installation Location: Distribution box.

Key Parameters: In (Rated Discharge Current), Up (Voltage Protection Level).

Objective: To provide final, lowest residual voltage protection for the most sensitive electronic equipment.

Installation Location: Front end of the equipment, as close as possible to the protected equipment (typically <10 meters).

Key Parameters: Up (Voltage Protection Level), Uoc (Open Circuit Voltage).

Basic: Install one Type 2 SPD in the main switch box.

Standard: Install a Type 2 SPD in the main switch box and equip valuable appliances (such as computers and televisions) with Type 3 Surge Protector power strips.

Advanced (Villas, High-Speed ​​Lightning Areas): Install a Type 1 SPD at the main incoming line, install Type 2 SPDs in the distribution boxes on each floor, and use Type 3 power strips for terminals.

Install a Type 1 SPD in the main distribution room.

Install Type 2 SPDs in the distribution boxes and server room cabinets on each floor.

Install dedicated Type 3 SPDs or rack-mounted SPDs in front of servers, network switches, and storage devices.

Install a Type 1/2 SPD in the main incoming line cabinet.

Install Type 2 SPDs in front of each control cabinet, PLC cabinet, and frequency converter.

When selecting an SPD, be sure to pay attention to the following key parameters:

The SPD must be able to withstand the maximum AC or DC voltage for extended periods without starting. This voltage must be higher than the nominal voltage of the local power grid. For example, in a 230V area, Uc should be at least 275V or higher.

For Type 1 SPDs, this indicates the maximum peak lightning current it can withstand with a 10/350µs waveform. The higher the value, the stronger its resistance to direct lightning strikes.

Primarily used for testing and defining the performance of Type 3 SPDs, it represents the waveform of the test voltage applied to the SPD.

This is one of the most important parameters, representing the residual voltage across the SPD after it trips. The Up value must be lower than the withstand voltage level of the protected equipment. The lower the value, the better the protection effect.

For Type 2 SPDs, this indicates that it can withstand 15 peak current surges from an 8/20µs waveform. It is a key indicator of the discharge capability of a Type 2 SPD.

Surge Protection Device (SPD) is a comprehensive technical term, while Surge Protector and Surge Arrester are specific expressions of it in different contexts and application levels.