High Voltage Glass Insulators: Everything You Should Know

A high voltage glass insulator, also known as a toughened glass insulator, is an electrical insulation component used in high-voltage transmission and distribution lines. It is typically assembled into insulator strings to support conductors and prevent current leakage. First manufactured around the 1950s, the high voltage glass insulator has been widely used ever since due to its excellent mechanical strength and electrical performance.

How are High Voltage Glass Insulators Made?

The high-voltage glass insulator comprises a toughened glass disc, a hot-dip galvanized cap and pin, and a stainless steel security clip, all bonded with high-strength cement adhesive.

High Voltage Glass Insulator Manufacturing Process (How the Toughened Glass Disc Is Made)

1. Raw Material Preparation – 2. Melting – 3. Molding – 4. Annealing – 5. Toughening (Tempering) – 6. Quality Inspection – 7. Storage and Transportation

Production Line Diagram for High Voltage Glass Insulators

How do High Voltage Glass Insulators Work?

Mechanical Support
High voltage glass insulators withstand mechanical stresses such as tension, wind, and ice loads through:

• Tempered glass strength – Enhances durability and ensures line stability.
• Series configuration – Multiple insulators in a string adapt to different voltage and load requirements.
• Self-destruction feature – If broken, the glass shatters safely while metal fittings remain connected, preventing system failure.

Electrical Insulation
High voltage glass insulators prevent high-voltage conductors from leaking current to grounded towers or poles through:

• High resistance material – Glass is a poor conductor, effectively blocking current flow.
• Extended creepage distance – Disc or open-type designs increase the surface path to reduce flashover caused by pollution.
• Anti-pollution properties – The smooth glass surface resists dust accumulation, minimizing electrical breakdown risks.

How to Choose the Right High Voltage Glass Insulators: 3 Key Considerations

1. Drawings and Technical Parameters of High Voltage Glass Insulators

When selecting glass insulators, the following key technical parameters should be considered:

• Nominal Creepage Distance: A longer creepage distance helps prevent leakage or breakdown caused by surface polarization of the insulating material, ensuring the safe operation of electrical equipment.
• Minimum Mechanical Damage Load: For example, 120 kN (as shown in the drawing).
• Suitable Coupling Size: A standardized size facilitates the assembly of a stable insulator string.
• Hot-Dip Galvanized Accessories: Corrosion-resistant for long-term durability.

You can choose between IEC or ANSI international standards based on the requirements of your power transmission and distribution project. To purchase glass insulators, simply provide your drawings and technical specifications to the manufacturer for verification. They will then produce and quote based on your requirements.

2. Line Voltage Selection

The appropriate high-voltage glass insulator should be selected based on the line voltage. You can refer to the table below for guidance.

Based on Gaoya Power‘s 20 years of experience in supplying glass insulators:

• For 220 kV transmission lines, glass insulators with a mechanical strength of 160 kN or higher are recommended.
• For 500 kV and above ultra-high voltage (UHV) lines, glass insulators with a mechanical strength of 300 kN or more are typically used.

3. Environmental Considerations

Different environmental conditions require different types of high voltage glass insulators for optimal performance:

• Standard Glass Insulators: Suitable for low-pollution areas with conventional environmental conditions.
• Anti-Pollution Glass Insulators: Recommended for high salt fog, high humidity, and highly polluted areas, as they feature a longer creepage distance to prevent contamination-related failures.
• Aerodynamic Glass Insulators: Best suited for arid and sandy environments, where their streamlined design helps reduce dust and rain adhesion. These insulators are also ideal for use in deserts and industrial pollution zones.
• Standard Insulators in Cold Climates: In extremely cold environments without nearby pollution sources, standard glass insulators are an appropriate choice.

How do Pollutants Affect High-Voltage Glass Insulators?

Pollutants like dust, industrial emissions, salt spray, and bird droppings can weaken the performance of glass insulators in several ways:

• Reduced Insulation & Conductive Layer Formation
  Moisture turns surface contaminants into a conductive layer, increasing leakage current and possibly leading to arc discharge or flashover.
• Pollution Flashover Risk
  In humid or foggy conditions, pollutants lower surface resistance, making it easier for high voltage to break down the air, causing sudden short-circuit discharge.
• Increased Leakage Current & Energy Loss
  A continuous conductive path from wet pollutants raises leakage current, causing power loss, overheating, and faster aging of the insulator.

Four Solutions to Reduce the Effects of Pollution on High-Voltage Glass Insulators

• Use Anti-Pollution Insulators
  Designed with long creepage distances, these insulators extend the surface path for leakage current, reducing the risk of flashover.
• Perform Regular Cleaning
  High-pressure water washing or manual cleaning helps remove accumulated contaminants and maintain insulation performance.
• Apply Anti-Fouling Coatings
  Coatings like silicone rubber enhance water repellency, preventing moisture absorption and reducing flashover risk.
• Optimize Insulator Configuration
  Increasing the number of insulators improves the overall insulation level, reducing the impact of environmental pollution.

Why Choose High-Voltage Glass Insulators?

• High Mechanical Strength and Safety
  High-voltage glass insulators are heat-treated (tempered), giving them excellent mechanical tensile strength. They can easily withstand line tension, making them ideal for long-span transmission lines and areas with strong winds. Standard products typically offer tensile strength ranging from 40kN to 300kN, ensuring a high safety margin.
• Smooth Surface – Less Dust Accumulation
  The surface of glass insulators is very smooth, which helps prevent dust build-up. This makes them perform better than porcelain or polymer insulators in areas with moderate to heavy pollution, maintaining superior insulation performance over time.
• Visible Self-Breakage – Easy Inspection & Maintenance
  In the event of a fault or internal electrical breakdown, a glass insulator will shatter into small pieces (a process known as self-explosion). Still, the metal hardware remains intact and connected. This makes it easy for maintenance personnel to spot damaged units with the naked eye, greatly improving inspection speed and overall efficiency.
• Long Service Life and Low Operating Costs
  High voltage glass insulators offer outstanding resistance to aging and deterioration. Unlike porcelain insulators, they do not suffer from electrical performance degradation over time. With a typical lifespan of over 30 years, they require minimal maintenance, resulting in significantly lower long-term operating and maintenance costs.
• Eco-Friendly and Fully Recyclable
  Glass is a non-toxic, inert material that can be 100% recycled in the glass manufacturing industry.
  Additionally, the metal components (such as caps, pins, and split pins) are recyclable, and the hardened cement filler can be crushed into small pieces for use as Recycled Concrete Aggregate (RCA) in construction applications.