Well-known manufacturer of drop cable connections: product catalog 

High-voltage splicing: selection criteria and technical requirements for the reliability of power grids

The stability of distribution networks directly depends on the quality of power cable connections.High voltage splicingis not just a mechanical connection of two conductors, but a complex engineering unit that ensures continuity of electric current while maintaining the dielectric strength of the insulation. Errors at this stage lead to local overheating, insulation breakdown and emergency shutdowns, the cost of which is many times higher than the price of a high-quality coupling. In our practice, we have repeatedly encountered the consequences of using cheap analogues: restoration of a 10–35 kV line requires not only the replacement of equipment, but also lengthy excavation work.

The choice of connection technology is determined by the type of cable insulation (cross-linked polyethylene or oil-filled paper), operating voltage and operating conditions. For modern networks, cold-shrinkable and heat-shrinkable solutions are preferred, which ensure tightness and resistance to mechanical stress. CompanyShijiazhuang Hist Electric Co.,Ltdoffers a product catalog developed taking into account harsh climatic conditions and high requirements for electrical safety, which allows minimizing the risks of infrastructure failures.

Technological features of high-voltage splicing

The process of creating reliable contact in high-voltage lines requires precise adherence to the physics of the electric field. The main task of the coupling is to equalize the electric field strength at the junction of the conductors, where the geometry of the conductor is broken. If this is not done, corona discharges will occur, which will gradually destroy the insulation. We use semiconducting layers and voltage cones for smooth potential transition, which is standard for voltage class products above 1 kV.

There are two main approaches to installing connections:

• Heat-shrinkable sleeves.Requires the use of open fire (gas burner) to shrink polymer tubes. This method has been proven for decades, but requires highly qualified installers. Overheating can damage the cable insulation, and underheating will leave microvoids filled with air, which will lead to breakdown.
• Cold-shrinkable couplings.Manufactured from elastomeric silicone rubber with pre-stretched elements. When the protective core is removed, the material tightly compresses the cable due to its own elasticity. This method eliminates the human factor associated with temperature conditions and allows work to be carried out in windy weather or near flammable materials.

In the laboratory of Shijiazhuang Hist Electric LLC we carry out comparative tests of both types. The results show that cold-shrinkable joints exhibit better resistance to cyclic thermal expansion, as silicone remains flexible in the range from -50°C to +90°C. This is critical for regions with extreme temperature changes, such as Siberia or the northern provinces of China.

Catalog of solutions for medium and high voltage

Our product line covers the needs of networks with voltages from 1 kV to 35 kV and above. Each product undergoes multi-stage quality control. Below are the key product categories available for order.

Connectors for cables with cross-linked polyethylene (XPE) insulation

This is the most popular category for modernizing city networks. The couplings are designed for connecting single-core and three-core cables. The design includes an electric field equalization system, a recovery screen and an outer protective shell. We offer models for both indoor and outdoor installation. External versions have enhanced protection from ultraviolet radiation and moisture, which is confirmed by tests on the aging of the material.

End seals (heat-shrinkable and cold-shrinkable)

Proper cable termination is just as important as splicing. Our terminations provide a reliable transition from the cable line to the equipment (transformers, switches). The range includes solutions for voltages of 1 kV, 10 kV, 11 kV and 35 kV. Particular attention is paid to the quality of contact tips: they are made of tinned copper or aluminum, which prevents oxidation of the contact and an increase in contact resistance.

Accessories for switchgears

In addition to cable accessories, we supply comprehensive solutions for line protection. The catalog contains:

• Isolating switches of the GW4-15 and GW13 series, providing a visible circuit break for safe repair work.
• Lightning rods for voltages of 10 kV and 11 kV, protecting equipment from impulse overvoltages of atmospheric origin.
• RW5-35 kV fuses and HRW12-35 kV wind protection fuses, which quickly disconnect the damaged section of the network, preventing the spread of the accident.
• Support porcelain insulators characterized by high mechanical strength and resistance to contamination.

All components are designed to work together, simplifying design and procurement for contractors. The company's engineers help you select compatible elements, eliminating the risk of mismatching dimensions or electrical characteristics.

Production control and laboratory testing

Trust in the supplier of electrical products is built on the transparency of control processes. The production base in Shijiazhuang is equipped with one of the largest electrical engineering laboratories in Northern China. A full cycle of testing is implemented here: from incoming inspection of raw materials (silicon rubber, copper alloys, adhesives) to acceptance tests of finished products.

A key advantage is the ability to conduct high voltage tests in the range up to 1000 kV. This allows us to verify the safety margin of products operating in networks of 35 kV and below, with a fivefold overlap. We don’t just check compliance with GOST or IEC, we test products at extreme conditions. For example, every batch of couplings is tested for partial discharges. The level of partial discharges should not exceed 10 pC at operating voltage. Exceeding this threshold indicates the presence of microvoids in the insulation, which is a defect.

The company employs 256 specialists, including 7 doctors and candidates of science. This expertise allows us to constantly improve the formulations of polymer materials. More than a dozen active patents confirm the originality of our technological solutions. We do not copy other people's developments, but adapt them to real operating conditions, taking into account factors such as vibration, chemical aggressiveness of the soil and biological effects.

Logistics and delivery conditions for international partners

For foreign customers, including the CIS countries, the Middle East and Africa, we have organized a well-functioning logistics chain. Our own warehouse complex includes three specialized storage facilities, which allows us to maintain a stock of popular items and ship orders in the shortest possible time. Shipment is carried out both by road and by sea containers.

We understand that a delay in delivery may disrupt the construction schedule. Therefore, our production planning system includes reserve capacity. Each order is accompanied by individual technical support. Project managers work with customer engineers to clarify specification details before production begins to eliminate configuration errors.

Frequently Asked Questions

What type of coupling should I choose for difficult climatic conditions?

For regions with extremely low temperatures or high humidity, we recommend cold-shrinkable silicone rubber couplings. They do not require heating during installation, which eliminates the risk of thermal damage to the cable insulation in the cold. Silicone remains flexible at -50°C, while some thermoplastics become brittle. In addition, the hydrophobic properties of silicone prevent the formation of conductive films on the surface of the coupling.

Is special equipment required for installation?

Heat-shrinkable sleeves require a gas burner with a soft flame and a set of tools for cutting cables (knives, strippers, files). For cold-shrinkable systems, no special heating tool is needed; a standard installation kit is sufficient. However, in both cases, keeping the work area clean is critical. Dust or moisture getting under the insulation is the main cause of early failures, regardless of the quality of the product itself.

How can I confirm that a product meets my country's standards?

The products of Shijiazhuang Hist Electric LLC are certified according to the ISO 9001 system and comply with international IEC standards. For the markets of the Customs Union (EAEU) countries, we provide the necessary documents to confirm compliance with GOST. If necessary, we can organize additional independent tests in accredited laboratories of the importing country at the expense of the company, if this is provided for in the contract.

Conclusion and next steps

Reliablehigh voltage splicingis the foundation of power system security. Saving on the quality of cable accessories inevitably leads to increased operating costs and the risk of accidents. When choosing a supplier, pay attention not only to the price, but also to the availability of its own testing facilities, engineering competence and experience in implementing projects in similar climatic conditions.

Shijiazhuang Hist Electric LLC is ready to become your strategic partner in equipping energy facilities. We offer not just a product, but a proven solution, backed by technical support and a quality guarantee. Our specialists will help you select the optimal equipment configuration for your project, be it a city distribution network or an industrial facility.

Contact us today for a detailed catalogue, technical specifications and quotation. Our engineers are ready to answer your questions and help with the calculation of the necessary materials.