Support insulators – find manufacturers and suppliers

Support insulators are electrical insulators that mechanically support cables or live parts and at the same time insulate them electrically from earth or other conductors.

In contrast to suspension or guy insulators, which primarily absorb tensile forces, support insulators are primarily designed for compressive and bending forces.
They are indispensable in the high and medium voltage range - in substations, switchgear and on overhead lines.

Below you will find an overview of the structure, functionality and areas of application of support insulators, the requirements and tests and the advantages of modern variants:

Structure and materials of support insulators:

A typical back-up insulator consists of an insulating body, often made of:

1. Porcelain - traditional and widely used; high mechanical strength and good weather resistance.
2. Composite materials e.g. fiberglass/plastic combinations - increasingly used due to their lighter weight, resistance to breakage and good electrical properties.

Both variants have metal end fittings for fastening at the top and bottom - e.g. for screw connections with conductor rails or for mounting on foundations.

How support insulators work:

The functionality of support insulators can be divided into two main aspects:

1. Mechanical function:
   They support the weight of the connected electrical conductors, as well as additional loads caused by wind, ice, vibrations or switch movements. In doing so, they must be mechanically stable and firmly connected to other components.
2. Electrical function:
   Support insulators prevent current from flowing from the live parts to the earthed structure. They provide reliable insulation against high voltages, often over several hundred kilovolts. To do this, they must provide a sufficiently large creepage distance and air gap to prevent flashovers or leakage currents - especially under damp or dirty conditions.

Areas of application for support insulators:

Back-up insulators are used in many areas of the energy supply:

1. Substations:
Here they support busbars, switches or terminals, often in outdoor installations.
They have to withstand voltages of up to 800 kV and resist weather influences such as rain, snow or industrial pollution.

2. Switchgear:
In indoor switchgear - especially in gas-insulated systems (GIS) - smaller variants with specifically adapted insulating material are often used.

3. Overhead lines:
In the case of particularly high voltages or special designs, support insulators are also used to secure cables to pylons, especially at crossing points or branches.

4. Traction current systems:
In traction current systems, e.g. 15 kV at 16.7 Hz, support insulators are used on masts and support structures for overhead contact lines.

Requirements and testing of support insulators:

Support insulators must withstand standard-compliant tests, such as:

• Mechanical load tests such as compression, bending and torsional strength.
• Electrical dielectric strength even when wet.
• Weather resistance to temperature fluctuations and UV radiation.
• Ageing tests for plastics and composite materials.

Advantages of modern variants of support insulators:

Modern composite insulators have several advantages over traditional porcelain models:

• Lower weight → Easier to transport and install
• Greater resistance to breakage → no splintering in the event of mechanical damage
• Better resistance to soiling → Less cleaning required
• Flexible design → Adaptation to complex system designs

Support insulators are essential components of the electrical energy infrastructure. They enable high-voltage systems to function safely and reliably for decades. Their combined mechanical and electrical function makes them a key component - whether made of classic porcelain or innovative composite materials. Technical progress is producing ever more efficient and durable designs that meet the increasing requirements of modern energy networks.

Below is an overview of the most important points to consider when purchasing support insulators:

When purchasing support insulators - especially for applications in high-voltage, medium-voltage or traction power systems - there are several technical, economic and qualitative aspects to consider. These not only ensure safe and reliable operation, but also influence the maintenance costs, service life and overall profitability of the system.

• The insulator must be designed for the respective operating voltage. Dimensioning for lightning impulse voltage and switching impulse voltage is also important, as these can occur in the event of a fault or atmospheric events.
• The creepage distance - i.e. the distance that a leakage current would travel across the insulator surface - is a key selection criterion. In regions with high levels of pollution, sea air or industrial emissions, the creepage distance must be particularly long.
• High-quality insulators should not exhibit partial discharges at rated voltage. Otherwise, premature ageing or insulation failure may occur.
• The insulator must be able to safely absorb the planned mechanical loads - such as the dead weight of cables, switchgear or dynamic forces caused by switching operations and wind loads.
• Depending on the type of installation and function, the insulator must be able to withstand different forces. Manufacturers usually specify permissible loads or breaking loads, which must be compared with the actual operating conditions.
• The choice of material should take into account the expected requirements:
• Porcelain is robust, durable and tried and tested. It is well suited to heavy soiling, but heavier and sensitive to breakage from mechanical impact.
• Composite insulators are lighter, unbreakable and flexible. Particularly suitable for modern outdoor installations or mobile applications. The ageing resistance of silicone or EPDM surfaces must be tested.
• Support insulators must be adapted to the local climatic and environmental conditions:
• Temperature range: Extreme heat or cold.
• Degree of soiling according to IEC/EN classification.
• UV resistance
• Precipitation and humidity
• Snow, ice and wind load zones
• Depending on the place of use, it is advisable to select special versions, e.g. with larger screens or hydrophobic coatings.
• A professional purchasing department must ensure that the insulators meet all relevant standards and quality requirements:
• IEC 60273, IEC 62231, IEC 60383 depending on the design.
• Type tests and routine tests by independent test centers.
• Quality certificates e.g. ISO 9001, ISO 17025 for test centers.
• The manufacturer should also be able to provide technical data sheets, test reports and documentation in a transparent manner.
• Professional purchasing not only pays attention to the unit price, but also to delivery times and security:
• Delivery times and reliability.
• Availability of replacement insulators for years to come.
• Packaging, transportation and storage requirements.
• Traceability of batches, e.g. serial numbers, batch labels.
• A stable logistics chain is crucial, especially for larger systems or series deliveries.
• For retrofit or conversion projects in particular, it is important that the support isolators are installation-compatible with existing systems (hole spacing, heights, connection types). Maintenance-free or low-maintenance variants are particularly advantageous from an economic point of view.
• A favorable purchase price must not obscure long-term operating costs. Criteria such as:
• Maintenance effort.
• Cleaning cycles, especially in regions prone to soiling.
• Service life of 30-50 years for high-quality products.
• Recyclability of materials.
• Energy consumption in production.
• Are increasingly included in the evaluation of suppliers.

When purchasing support insulators professionally, you should not just look at price or standard data, but take a holistic view - technical requirements, environmental conditions, quality certificates, service life and logistics aspects. This is the only way to ensure that the insulators function reliably in operation over the long term and contribute to the efficiency and safety of the entire energy system.

Support insulators can be purchased from various suppliers. You will find comprehensive information on manufacturers and suppliers of Supporting insulators around the world on Exportpages.