Suspension Type Insulator
Suspension type insulators are generally made of insulating parts (e.g. porcelain, glass parts) and metal accessories (e.g. steel feet, iron caps, flanges, etc.) glued together with adhesive or mechanically clamped. Insulators are widely used in power systems and mostly belong to external insulation, working under atmospheric conditions. Overhead transmission lines, busbars of power plants and substations, and the external live conductors of various electrical equipment must be supported by insulators and insulated from the earth (or grounded objects) or other conductors with potential differences.
ZMS can produce low, medium, and high-voltage standard insulators in epoxy resin, ceramic, polymer material, and glass. We can produce any type of insulator product according to your project requirements. Contact us now for more competitive polymer suspension insulator prices.
Types Of Suspension Insulator Products
Polymer Suspension Insulators
Polymer suspension insulators are used for overhead lines and substations for draping and tensioning in common and foul areas of AC power systems with rated voltages from 35 to 500 kV and frequencies not exceeding 100 Hz. The power line insulators are installed in the ambient temperature range from -40℃ to +40℃, and the altitude does not exceed 1000m, especially in foul areas, and can effectively prevent fouling and flashing accidents, which is an alternative product to the widely used porcelain insulators.
The main structure of composite insulators also called the synthetic insulator, consists of three parts: umbrella skirt sheath, epoxy glass fiber (FRP) core rod, and end fittings. The FRP core rod is an FRP Polymer material with glass fiber as reinforcement and epoxy resin as matrix, and the end fittings are carbon cast steel or carbon structural steel with hot-dip galvanized coating.
The Polymer insulator products are used for insulating and suspending wires in high-voltage and ultra-high-voltage AC and DC transmission lines.
Porcelain Suspension Insulators
The porcelain suspension insulators are composed of a single or a string of insulating discs suspended from a tower. It operates at a voltage of 33kv or more. The insulator caps are made of high-density ductile iron and we test each cap by magnetic particle testing method. The overhead cable insulator pins are made of forged steel, a material that ensures that the interior of the pin is free of any defects such as air, holes, cracks, etc. Both caps and pins are hot-dips galvanized and the thickness of zinc conforms to ASTM 135.
We produce disc porcelain with high alumina porcelain C120, which is covered with a hard glaze, and the color can be gray, brown, white, or according to the customer’s requirements.
The material of the R-lock pin is stainless steel, which guarantees a very secure insulator string connection.
We use excellent Portland cement to assemble the overhead line insulators with the associated caps and pins, and the cement remains good even after years of maintenance.
Characteristics and Differences Between Polymer Insulators and Ceramic Insulators
1. Strong anti-fouling flash synthetic insulator surface is water repellent, water is glistening on it, not easy to form conductive pathways, plus the small diameter of synthetic insulator umbrella disc, large creepage distance, high surface resistance, and small leakage current. Therefore, it has a high foul flash voltage.
2. High strength and lightweight: Because of the high tensile strength of the rod core, the synthetic insulator can be made very light to reduce the force on the tower and save a lot of cost by reducing the installation and maintenance intensity.
3. Good anti-aging properties: synthetic insulators have good corrosion resistance and anti-aging property, still have elasticity at 70℃, and can work for a long time at 20℃.
4. Small volume and lightweight: Due to the small volume and light weight of synthetic insulators, and the flexible umbrella disc, they are not easy to break. Therefore, it brings great convenience to transportation, installation, and maintenance.
Application of composite insulators, although the price is higher than porcelain insulators, from the long-term comprehensive economic benefits, the polymer insulator is the most ideal material. And the higher the voltage, the more obvious the economic benefits.
1. More environmentally friendly: it is made from natural materials by simple mixing and curing. It can be stored in landfills with other wastes. It can be used as a recycling material for the production of ceramics and similar products.
2. It has higher electrical strength compared to polymers: dry-state porcelain insulators have better electrical properties than polymers as electrically insulating materials, type electrical tests show better results, and have a longer service life in terms of loads generated by electrical charges and other temporary electrical phenomena.
3. High heat resistance and strength, Ceramics can withstand temperatures up to 1000 ° C; significantly higher resistance to surface degradation, charging without degradation or carbonate; the surface is stable to ultraviolet radiation.
4. Ceramic insulators have a highly smooth and hard surface that is resistant to rodents, termites, birds, and other animals capable of destroying the integrity of the polymer.
5. The high plasticity of the ceramic insulator production process, the possibility of precision grinding, and the very easy adhesion and good mechanical properties give it a wide range of applications: contactors, disconnect switches, equipment transformers, capacitors, also solenoid rings with extreme surfaces, atypical insulators (filters).
6. The highly vitrified surface of Porcelain insulators gives the product better self-cleaning properties in highly contaminated areas; it is highly resistant to corrosion in acidic and corrosive environments.
7. The combination of ceramic insulators with cast iron or aluminum structures using conventional cement resists transition phenomena during discharge or brush discharge.
8. The Porcelain material provides very high mechanical strength under pressure and hardness: the ceramic insulator will not deform unless an external force is applied. It guarantees a service life of up to 40 years. Thus, providing a long-term operational reference for many users in numerous applications.
9. Modified design to suit the environment: the product is offered in a wide range of shapes during production.
10. The ceramic insulator looks better: it has a timeless design.
In general, overhead line insulators are designed to ensure good insulation between transmission fixed poles, transmission lines, parts of the transmission lines, and the earth. It is designed to avoid short circuits caused by the contact between the transmission line and the rest of the conductors during the transmission of electricity and has a pivotal role in electricity.
Types Of Overhead Line Suspension Insulators
The umbrella insulator is the oldest type of suspension insulator in use. It is characterized by its simple structure and shape, low cost, and is suitable for use in clean areas. They are usually used on AC transmission lines.
The disk-type suspension insulator is the most common and important type of line insulator in use. This cable insulator consists of an iron cap, insulating porcelain parts, and feet glued together with a cementitious adhesive.
Steel feet and iron cap and the adhesive contact surface are thinly coated with a buffer layer, generally asphalt, steel feet between the top porcelain parts with elastic liner.
The surface of the porcelain parts generally on the white glaze, iron cap and steel foot surface all hot-dip galvanized.
The edge of the lower mouth of the cap and the insulating parts between the appropriate gap to avoid material expansion when the insulating parts by stress damaged.
There are two main types of disc-shaped suspended porcelain insulators: ball-and-socket connection and slot connection. The ball-and-socket connection structure is non-directional and has the advantage of easy assembly and disassembly, especially for replacing insulators with electric power. Therefore, the ball-and-socket connection structure is generally used on high-voltage, ultra-high-voltage, and extra-high-voltage lines.
The slotted connection structure, with its simple connection fixture, is not convenient for live operation and is generally used in lower voltage lines.
To ensure that the insulators do not fall off from the string during operation, each insulator is equipped with a locking device. In the ball and socket connection structure, locking pins are used, and in the slot connection structure, cylindrical pins are used and locked with cotter pins or humpback pins.
This umbrella insulator has a long under-umbrella prong. The product can achieve a large creepage distance, the inner cavity under the umbrella is not easy to damp, and has a high fouling withstand voltage. It is more suitable for use on AC and DC transmission lines in coastal, foggy and humid, and saline areas.
This type has a particularly large diameter umbrella disc, a smooth, non-ribbed umbrella, a streamlined structure, good self-cleaning properties, and low dirt accumulation.
The use of characteristics is interspersed in the upper and middle of the overhead electric wire insulator dangling string of AC and DC lines, and the extra large disk diameter structure can play a role in inhibiting the occurrence of line dirt flashover caused by ice skating and bird droppings.
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