110kv Glass Disc Insulators for Transmission Line
| IEC designation | U40B/110 | U70B/146 | U70B/127 | U100B/146 | U100B/127 | U120B/127 | U120B/146 | U160B/146 | U160B/155 | U160B/170 | |
| Diameter D | mm | 178 | 255 | 255 | 255 | 255 | 255 | 255 | 280 | 280 | 280 |
| Height H | mm | 110 | 146 | 127 | 146 | 127 | 127 | 146 | 146 | 155 | 170 |
| Creepage distance L | mm | 185 | 320 | 320 | 320 | 320 | 320 | 320 | 400 | 400 | 400 |
| Socket coupling | mm | 11 | 16 | 16 | 16 | 16 | 16 | 16 | 20 | 20 | 20 |
| Mechanical failing load | kn | 40 | 70 | 70 | 100 | 100 | 120 | 120 | 160 | 160 | 160 |
| Mechanical routine test | kn | 20 | 35 | 35 | 50 | 50 | 60 | 60 | 80 | 80 | 80 |
| Wet power frequency withstand voltage | kv | 25 | 40 | 40 | 40 | 40 | 40 | 40 | 45 | 45 | 45 |
| Dry lightning impulse withstand voltage | kv | 50 | 100 | 100 | 100 | 100 | 100 | 100 | 110 | 110 | 110 |
| Impulse puncture voltage | P.U | 2.8 | 2.8 | 2.8 | 2.8 | 2.8 | 2.8 | 2.8 | 2.8 | 2.8 | 2.8 |
| Power frequency puncture voltage | kv | 90 | 130 | 130 | 130 | 130 | 130 | 130 | 130 | 130 | 130 |
| Radio influence voltage | μv | 50 | 50 | 50 | 50 | 50 | 50 | 50 | 50 | 50 | 50 |
| Corona visual test | kv | 18/22 | 18/22 | 18/22 | 18/22 | 18/22 | 18/22 | 18/22 | 18/22 | 18/22 | 18/22 |
| Power frequency electric arc voltage | ka | 0.12s/20kA | 0.12s/20kA | 0.12s/20kA | 0.12s/20kA | 0.12s/20kA | 0.12s/20Ka | 0.12s/20Ka | 0.12s/20Ka | 0.12s/20Ka | 0.12s/20Ka |
| Net weight per unit | kg | 2.1 | 3.6 | 3.5 | 4 | 4 | 4 | 4 | 6.7 | 6.6 | 6.7 |
Material
It's primarily made of toughened or annealed glass. This glass acts as the dielectric material, meaning it prevents the flow of electric current.
Form
It typically consists of individual disc-shaped or bell-shaped units. Each unit has a metal cap on top and a metal pin underneath, bonded to the glass body with cement (usually Portland cement).
Function
Its main purpose is to electrically isolate the high-voltage conductor (the power line wire) from the grounded support structure (the transmission tower or pole). It also mechanically supports the weight of the conductor.
Advantages of Glass Insulaators
High Dielectric Strength than Porelain Insulators:
Glass is an excellent insulating material with high resistance to electrical breakdown.
Transparency / Ease of Inspection than Porelain Insulators:
This is a major advantage. Damage, such as cracks or punctures caused by electrical stress (arcing) or physical impact, is often easily visible. If a toughened glass insulator fails due to excessive stress, it tends to shatter completely, making the faulty unit obvious from the ground during line inspections. This simplifies maintenance significantly compared to porcelain, where internal cracks might not be visible.
High Mechanical Strength than Porelain Insulators:
Toughened glass has high tensile strength, allowing it to reliably support the mechanical load of heavy conductors, wind, and ice.
Resistance to Environmental Degradation than Porelain Insulators:
Glass is highly resistant to UV radiation, chemical pollutants, and acid rain. It doesn't age or degrade significantly over long periods of sun exposure.
Stable Properties than Porelain Insulators:
The electrical and mechanical properties of glass remain relatively stable over a wide range of temperatures.
Lower Coefficient of Thermal Expansion than Porelain Insulators:
This makes it less susceptible to cracking due to sudden temperature changes compared to porcelain.
Self-Cleaning Properties:
The smooth surface of glass helps shed dirt and pollutants more easily with rain, which helps maintain its insulating capability in contaminated environments (though heavy contamination can still affect performance).
Cost-Effectiveness than Porelain Insulators
Often, glass insulators provide a good balance of performance, longevity, and cost compared to alternatives.