How to Identify the Quality of Glass Insulators?

Do You Know How to Identify the Quality of Glass Insulators? Now, Let's Learn together with China Qualified Glass Insulator Manufacturer-Nooa Electric:

1. Glass Surface
High-quality insulators: Smooth and transparent surface without bubbles, cracks, impurities, or ripples.

Inferior products: Visible bubbles, inclusions, or white haze indicate poor melting and molding processes.

2. Metal Cap and Pin

The zinc coating should be uniform, free from rust, and the welding joints must be smooth without cracks.

3. Cementing Part

The cemented area should be full, even, and free from bubbles or separation.

Mechanical Strength
1. Mechanical Failing Load Test
Each type (e.g., U70B, U120B, U160B) must meet its rated mechanical failing load.
High-quality products remain intact under 1.5 times rated load.

2.Tensile and Joint Reliability
The joint between the metal cap and pin must be firm and stable.
Hot-dip galvanization ensures corrosion resistance and 20+ years of service life.

Electrical Performance
1.Power Frequency Withstand Test

The insulator should withstand power frequency voltage (50Hz, 70–90kV) for 30 seconds under wet conditions without flashover or breakdown.

2. Lightning Impulse Test
High-quality insulators resist lightning or switching surges without premature breakdown.

3. Dielectric Loss Angle (tan δ)
A smaller tanδ indicates higher glass purity and better insulation.

Thermal Shock Resistance
Thermal Shock Test
The insulator is immersed from 90°C hot water into 0°C cold water three times without cracking.
This test indicates the quality of glass tempering and internal stress distribution.

Self-Indicating Feature of Zero-Value
Once a glass insulator fails electrically, it turns milky white, making identification easy.
Inferior products may not shatter completely, increasing operational risks.

Material and Manufacturing Process

Item	High-Quality Insulator	Low-Quality Insulator
Raw Material	High-purity silica glass	Recycled or impure glass
Tempering Process	Uniform temperature control	Uneven or insufficient tempering
Cementing	Vacuum-sealed, full adhesion	Weak or uneven adhesion
Zinc Coating	Hot-dip galvanized ≥85μm	Thin or uneven coating
Standards	IEC 60383 / GB/T 1001	compliant Non-standard or fake report

Must include type test and factory test reports.
Tests should cover mechanical load, electrical withstand, thermal shock, and adhesion strength.
Reports must be issued by accredited labs such as Xi’an High Voltage Institute or China Southern Power Grid Test Center.

Reputable glass insulator manufacturers (e.g., Nooa Electric, Sediver) have extensive experience in high-voltage transmission projects worldwide.
Their toughened glass insulators maintain low loss rates and stable performance after years of operation.

So, You have to know To evaluate the quality of a glass insulator, we should focus on appearance, electrical strength, mechanical load, thermal stability, manufacturing process, and certification.

A high-quality toughened glass insulator should have:

Smooth, defect-free glass surface.
High mechanical and electrical strength.
Excellent thermal stability and self-indicating behavior.
Compliance with international standards and certified reports.
Premium glass insulators significantly extend service life, reduce maintenance costs, and ensure reliable power grid operation.