DGG Polymer-Housed Metal Oxide Surge Arrester for Power Distribution Systems

Main Function

1. Lightning Overvoltage Protection

Protects electrical equipment from transient voltage surges caused by lightning.

2. Switching Overvoltage Protection

Helps limit overvoltages generated during power system switching operations.

3. Surge Energy Discharge

Provides a controlled discharge path for surge energy during abnormal overvoltage conditions.

4. Insulation Coordination

Works with the insulation level of protected equipment to reduce the risk of insulation damage.

Key Features

Metal Oxide Varistor Technology
Uses metal oxide resistive elements to respond rapidly to transient overvoltages.

Polymer Housing
The polymer external insulation structure is suitable for outdoor transmission and distribution applications.

Fast Overvoltage Response
Provides rapid response when lightning or switching surges occur.

Multiple Product Configurations
Different dimensions, electrical ratings and mounting arrangements can be selected according to the application.

Suitable for Power Equipment Protection
Can be used with transformers, instrument transformers, circuit breakers, switchgear and other distribution equipment.

Project-Based Selection
Electrical parameters and mechanical configuration can be selected according to system and installation requirements.

Type Test Support for Selected Models
DGG documentation confirms a type test report for a 10kV AC gapless metal-oxide surge arrester; test documentation for other models should be confirmed according to the exact product.

Working Principle

Metal oxide surge arresters use nonlinear metal oxide varistor elements as the core protective component.

During normal operation, the arrester presents high resistance and only a very small current flows through it. When a lightning surge or switching overvoltage raises the voltage above the normal operating level, the resistance of the metal oxide elements decreases rapidly.

The surge current is then discharged toward ground, limiting the residual voltage applied to the protected equipment.

After the surge disappears and the system voltage returns to normal, the arrester returns to its high-resistance state and the power system continues normal operation.

Typical Installation Scenarios

Transformer Protection
Installed near transformers to limit lightning and switching overvoltages entering the transformer insulation system.

Overhead Distribution Lines
Used on overhead feeders and pole-mounted distribution systems for line equipment protection.

Substation Equipment Protection
Applied near switchgear, instrument transformers and other substation equipment.

Industrial Distribution Systems
Provides surge protection for electrical equipment in industrial power distribution networks.

Structure Description

The product adopts a polymer-housed outdoor structure consisting of an insulated housing, metal oxide varistor elements, upper and lower terminals, sealing components and mounting accessories.

Different product sizes and mounting structures are available to match different system and installation requirements.

Why Polymer-Housed Surge Arresters

Polymer-housed surge arresters are widely used in modern distribution systems because the external insulation can be designed with compact dimensions and suitable creepage distance for outdoor installation.

Compared with heavier traditional insulation structures, polymer housings can also help simplify handling and installation, especially in pole-mounted and outdoor distribution applications.

The exact housing design, creepage distance and environmental suitability should be selected according to pollution level, altitude and project specifications.

FAQ

Q1. What is a metal oxide surge arrester used for?

A metal oxide surge arrester is used to limit transient overvoltages caused by lightning and switching operations, helping protect transformers, switchgear, instrument transformers and other electrical equipment.

Q2. Where should a surge arrester be installed?

A surge arrester is normally installed close to the equipment being protected and connected between the energized conductor and ground according to the system design.

Q3. Can it be used for transformer protection?

Yes. Transformer protection is one of the common applications of metal oxide surge arresters.

Q4. What information is required to select a surge arrester?

System voltage, maximum operating voltage, arrester rated voltage, MCOV, discharge current, protection level and installation environment should be confirmed before selection.

Q5. Are different housing sizes available?

Yes. The arrester size and external insulation configuration can vary according to voltage level, creepage distance and application requirements.

Q6. Does DGG have type test reports for surge arresters?

DGG documentation confirms a type test report for a 10kV AC gapless metal-oxide surge arrester. Availability of reports for other ratings should be confirmed according to the exact model.