35kV Single Core Intermediate Joint

Heat shrink power cable terminal heads and intermediate joint series products for 10KV ,20KV and 35KV applications, integrating waterproofing, stress control, and insulation.They have good electrical and mechanical performance, and can be used for a long time in various harsh environmental conditions.They have the advantages of light weight and easy installation. They are widely used in the fields of electricity, petrochemicals, metallurgy, railways, ports, and construction.

Heat shrink cable accessories, commonly known as heat shrink cable heads, are widely used for intermediate connections and terminations of cross-linked cables or oil immersed cables with voltage levels below 35KV . Compared with traditional cable accessories, they have the characteristics of small size, light weight, safety and reliability, and easy installation. The product complies with GB11033 standard, with a long-term use temperature range of -55 ℃ to 105 ℃, an aging life of up to 20 years, a radial shrinkage rate of ≥ 50%, a longitudinal shrinkage rate of<5%, and a shrinkage temperature of 110 ℃ to 140 ℃.

The materials used are generally blends of various material components such as polyethylene, ethylene vinyl acetate (EVA), and ethylene propylene rubber.

This type of product mainly uses stress tubes to deal with the problem of electrical stress concentration. Namely, they uses the parameter control method to alleviate stress concentration in the electric field.

The main advantages are light weight, easy installation,  good performance and low cost.

Stress tube is a type of heat shrinkable tube with moderate volume resistivity (1010-1012 Ω? cm) and high dielectric constant (20-25). It uses electrical parameters to force the stress at the insulation shielding fracture of the cable to disperse into a more uniform distribution along the stress tube. This technology can only be used in cable accessories of 35kV and below. Because when the voltage level is high, the stress tube will generate heat and cannot work.

The key technical issue in its use is to ensure that the electrical parameters of the stress tube must meet the specified values in the above standards before it can work. Additionally, it is important to use silicone grease to fill the air gap at the break of the cable insulation semiconductor layer to eliminate gas and reduce partial discharge. Cross linked cables may experience significant shrinkage during operation due to poor internal stress treatment. Therefore, when installing accessories, it is important to ensure that the stress tube and insulation shield overlap by no less than 20mm to prevent detachment during shrinkage.

Due to their low elasticity, heat shrinkable attachments may cause air gaps at the interface during thermal expansion and contraction during operation. Therefore, sealing technology is important to prevent moisture from entering.