Overhead line insulators are critical components that mechanically connect the conductor to the pole while electrically isolating it in medium and high voltage lines. Wrong insulator selection can lead to line faults, insulator breakages and prolonged power outages. In this guide, we cover insulator types and selection criteria.
Insulator Types
Pin-type insulators: Widely used in lines up to 36 kV, where the conductor is fixed at the top of the pole. With their simple and economical construction, they are the standard solution for urban distribution lines.
Suspension insulators: Formed by stringing discs in a chain; the number of discs is increased according to the voltage level. They offer a flexible and easy-to-maintain solution for high voltage lines.
Tension (strain) insulators: Withstand the mechanical pulling force at corner poles where the line changes direction and at termination points. These are the insulators exposed to the highest mechanical stress along the line route.
Material Comparison
- Porcelain: Proven durability over many years, high mechanical strength, affordable cost.
- Toughened glass: Provides easy maintenance with its self-revealing (visible breakage) structure when damaged.
- Composite (polymer): Lightweight, vandalism-resistant, superior hydrophobic performance in polluted environments; however, UV ageing should be monitored.
Key Selection Criteria
Nominal voltage and creepage distance: Sufficient creepage distance must be selected according to the voltage level of the line and the pollution degree of the region. Coastal and industrial areas require longer creepage distances.
Mechanical strength: A class appropriate to the pulling force determined by conductor cross-section, wind and ice load calculations must be selected.
Environmental conditions: Salinity, industrial pollution and temperature differences directly affect material selection.
Standards Compliance
Insulators must comply with IEC 60383 (porcelain and glass) and IEC 61109 (composite) standards and hold routine and type test reports.
ÖZ GÖKÇE Solutions
At ÖZ GÖKÇE ELEKTRİK, we supply suspension, tension and pin-type insulators as well as insulator ironworks in compliance with standards for overhead line projects. You can get support from our technical team for the right insulator selection for your medium voltage lines.
