Where Are Glass Insulators Used: By Voltage, Environment and Project Type?

Glass insulators are primarily used in AC lines ranging from：

High-voltage distribution lines (35 kV–110 kV), including urban/rural backbone distribution networks and county-level grid interconnection lines, offer advantages such as zero-value self-break functionality and convenient inspection, making them suitable for areas with limited maintenance personnel.

Ultra-high voltage transmission lines (220 kV–500 kV), including regional main transmission lines and inter-provincial link lines, possess mechanical strength and insulation stability sufficient to withstand conventional loads and mild ice accumulation conditions.

The ultra-high voltage AC line (750 kV and 1000 kV) is optimally suited for applications featuring uniform voltage distribution across string units, low corona loss, and minimal long-term insulation degradation, aligning perfectly with the long-life design requirements of UHV infrastructure. It serves as the standard insulator for China's 1000 kV UHV AC lines.

For ultra-high voltage (UHV) DC transmission lines (±500 kV and ±800 kV), dedicated DC-type glass insulators may be selected, primarily used in conventional sections of DC lines; heavily contaminated DC sections generally require models with anti-contamination structures.

Conventional overhead transmission lines: These are standard tower-based overhead lines deployed in plains and hilly areas, free from severe contamination or strong corrosion issues, offering the highest overall cost-effectiveness.

Large-span transmission lines： refer to those spanning rivers, highways, railways, or other long-distance routes. Glass insulators exhibit high mechanical strength (tensile resistance of 80–120 MPa), capable of withstanding high tension and strong wind loads. Even after failure, the metal components retain their mechanical integrity, eliminating the risk of conductor sagging. These insulators are therefore the preferred choice for cross-domain transmission lines requiring stringent safety requirements.

Tension section/turn tower lines: At line corners and tension towers, which endure continuous mechanical tension and vibration, glass insulators exhibit superior fatigue resistance and vibration performance compared to conventional porcelain insulators.

For substation outgoing lines/bus support structures, outdoor busbars at substations and converter stations, as well as incoming/outgoing line terminals, glass supports/disk insulators are employed to meet the insulation support requirements of high-voltage distribution equipment.

With features such as weather resistance, self-cleaning capability, and temperature stability, it is suitable for various complex outdoor environments, as detailed below:

Common meteorological regions (the preferred choice): inland plains and low mountainous areas with moderate temperature and humidity, free from significant dust or salt spray pollution, representing the most fundamental and widely used scenario for glass insulators.

Regions prone to ice accumulation and strong winds: Areas where ice formation is common during winter, persistent high winds occur year-round, and conductor swinging frequently happens. These areas possess strong mechanical load-bearing capacity, capable of withstanding ice-induced loads and cyclic impacts, with a temperature tolerance range of-50°C to +80°C.

High-altitude and strongly ultraviolet-exposed regions: Areas such as plateaus and mountainous regions experience intense ultraviolet radiation and significant diurnal temperature variations. Glass exhibits stable chemical properties, demonstrating no powdering, cracking, or aging due to ultraviolet radiation or abrupt temperature changes, ensuring consistent long-term performance.

General contaminated areas: regions with mild industrial dust or particulate emissions. The glass surface is smooth and dense, capable of self-cleaning under rainwater conditions, with minimal contamination accumulation and low susceptibility to pollution flash phenomena, requiring less frequent maintenance and cleaning.

In mountainous areas prone to frequent lightning strikes, power lines located in such regions exhibit excellent arc resistance, enabling rapid dissipation of lightning currents and reducing the likelihood of tripping due to lightning strikes.

The electrified railway contact network, serving both high-speed and conventional railways as an overhead power supply system, can withstand the continuous mechanical vibrations and frequent electrical surges generated by train operations.

New energy grid-connected transmission lines—those serving wind and solar power plants—feature complex routes and widely dispersed inspection points, while their zero-value self-break characteristic significantly increases inspection difficulty.

Long-life infrastructure projects: Key power grid projects and national transmission corridors with a planned service life of 50 years or more, where glass insulators exhibit less than 5% insulation performance degradation over 20 years of operation—significantly outperforming composite insulators in terms of service life and meeting long-term design requirements.

Route/Environment Type	Reasons for selecting the core component
1000 kV Ultra-High Voltage AC Power Transmission Line	Uniform voltage distribution, stable insulation performance, long service life, and easy maintenance inspection
220 kV to 500 kV ultra-high voltage power transmission lines	High mechanical strength, excellent aging resistance, and low overall cost
Crossing rivers or major road routes	High mechanical safety; failure does not cause derailment
Routes in high-altitude, thunder-prone mountainous areas	Resistant to ultraviolet radiation, temperature changes, and electric arcs
Polluted industrial areas	Surface self-cleaning, reducing the need for cleaning
Electrified railway lines connected to the grid	Vibration-resistant and fatigue-resistant
Heavy salt mist and areas with strong chemical corrosion	Custom anti-fouling model required; not the preferred option
Low-voltage lines with a voltage of 10 kV or lower	High procurement costs; not recommended

1. What voltage levels are glass insulators suitable for?

Glass insulators are commonly used on transmission and distribution systems ranging from 35 kV to 1000 kV AC and ±500 kV to ±800 kV DC. They are widely applied in distribution networks, regional transmission lines, EHV grids, and UHV power transmission projects due to their excellent insulation performance and mechanical strength.

2. Are glass insulators suitable for ultra-high voltage (UHV) transmission lines?

Yes. Toughened glass insulators are extensively used in 750 kV and 1000 kV AC UHV transmission systems because they provide uniform voltage distribution, low corona loss, excellent long-term insulation stability, and minimal aging. Dedicated DC glass insulators are also available for UHVDC transmission projects.

3. Why are glass insulators preferred for overhead transmission lines?

Glass insulators offer several operational advantages, including:

High mechanical strength
Excellent dielectric performance
Self-shattering zero-value indication
Low maintenance requirements
Long service life
Easy visual inspection

These features significantly reduce maintenance costs for utilities and EPC contractors.

4. Can glass insulators be used in polluted environments?

Yes, but the selection depends on the pollution severity. Standard glass insulators perform well in light and medium pollution areas thanks to their smooth, non-porous surface and natural rain self-cleaning capability. For heavily polluted coastal or industrial environments, anti-pollution profile designs or RTV-coated insulators are generally recommended.

5. Are glass insulators suitable for regions with ice and strong winds?

Yes. Toughened glass insulators possess high tensile strength and excellent fatigue resistance, enabling them to withstand heavy ice loads, conductor galloping, and strong wind conditions. They are widely used in cold-climate transmission projects.

6. What makes glass insulators suitable for long-span transmission crossings?

Large river crossings, highway crossings, and railway crossings require insulators with high mechanical reliability. Glass insulators provide outstanding tensile strength and maintain mechanical integrity even if the glass shell breaks, greatly improving line safety for critical crossing spans.

7. Which industries and infrastructure projects commonly use glass insulators?

Glass insulators are widely used in:

National transmission grids
Utility distribution networks
UHV transmission projects
Wind farm grid connections
Solar power transmission lines
Railway electrification systems
Hydropower projects
Cross-border interconnection projects
Industrial substations
EPC turnkey transmission projects