Inner Tapered Insulation Sleeves (Inner Tapered Sockets)
Product Overview
Inner Tapered Insulation Sleeves (Inner Tapered Sockets) are epoxy resin cast insulation components specifically designed for 10kV/24kV medium-voltage power distribution systems. Featuring an inner tapered interface structure, they serve as insulated connection bases between cable accessories and distribution equipment (ring main units, switchgear, pad-mounted transformers), providing conductive connection, insulation isolation, and mechanical support functions. They are the core components for achieving safe and reliable connections of separable cable accessories, and are widely used as cable inlet/outlet interfaces for indoor and outdoor distribution equipment.
Product Features
Electrical and Insulation Performance
Manufactured by integral casting with high-performance epoxy resin, the product is seamless and void-free with excellent insulation properties. It withstands the rated voltage and short-duration overvoltages of 10kV/24kV systems with sufficient insulation margin; partial discharge ≤10pC (at 1.5U₀).
Built-in electric field optimization structure and stress control layer uniformly distribute the electric field and effectively suppress partial discharge, eliminating the risk of electrical erosion and breakdown during long-term operation, with stable and reliable insulation performance.
Built-in copper/aluminum conductive inserts provide excellent conductivity with low contact resistance, capable of carrying the rated current of the corresponding current rating. Heat generation during long-term operation is minimal, with strong anti-corrosion and anti-oxidation performance.
The insulation surface is treated with a special process to achieve high surface resistivity and strong hydrophobicity, effectively preventing surface flashover caused by condensation and contamination, and improving insulation reliability in harsh environments.
Structural and Safety Features
Standardized inner tapered interface design strictly complies with GB/T 12706 and IEC 60840 standards, allowing universal interchangeability with inner tapered cable accessories of the same specification (elbow connectors, surge arresters, insulating caps) with strong compatibility.
Integrated structural design: the rear end features a flange mounting base for direct attachment to the distribution equipment enclosure, while the front end provides an inner tapered interface for insulation isolation and conductive connection between the equipment and cable accessories. Installation is convenient with no additional adapter components required.
Anti-misinsertion and anti-misconnection design: interface dimensions are uniquely matched, allowing connection only with cable accessories of the corresponding specification, eliminating mixed use of accessories of different ratings. Built-in positioning and locking structure prevents loosening and disengagement after installation.
Fully insulated structure with high outer insulation strength eliminates the risk of electric shock during operation, ensuring the safety of operation and maintenance personnel.
Environmental and Weather Resistance Performance
Excellent weather resistance suitable for a wide temperature range of -40°C to +90°C; epoxy resin performance does not degrade at high or low temperatures with no risk of cracking or embrittlement, adaptable to outdoor and indoor applications.
Moisture-proof, waterproof, pollution-resistant, and salt spray-resistant with IP67 protection rating, capable of long-term stable operation in humid, dusty, salt spray, and other harsh environments, immune to rainwater and condensation ingress.
Anti-aging, UV-resistant, and ozone-resistant with a service life exceeding 30 years. Maintenance-free operation reduces long-term operational and maintenance costs.
Mechanical and Compatibility Features
High mechanical strength with impact and vibration resistance, capable of withstanding mechanical stresses during transportation, installation, and operation without risk of deformation or damage; seismic resistance rating of Grade 8.
Flange mounting structure design compatible with standard mounting hole patterns of mainstream distribution equipment, allowing convenient installation without special tools.
Available in multiple specifications including 1#, 2#, and 3#, adaptable to distribution equipment and cable accessories of different voltage and current ratings with strong universality.
Technical Parameters
| Parameter Category | Parameter | Specification |
| Rated Electrical Parameters | System Voltage (Un) | 10kV/20kV |
| | Rated Voltage (Ue) | 12kV/24kV | |
| | Maximum Operating Voltage (Um) | 17.5kV/25.2kV | |
| | Rated Frequency (fn) | 50Hz/60Hz | |
| | Power Frequency Withstand Voltage | 42kV/5min (12kV dry test), 65kV/5min (24kV dry test), no breakdown, no flashover | |
| | Lightning Impulse Withstand Voltage | 95kV (12kV peak), 125kV (24kV peak), no breakdown, no flashover | |
| | Partial Discharge | ≤10pC (at 1.5U₀) | |
| | Rated Current Rating | 630A/1250A (multiple specifications available) | |
| | Rated Short-Circuit Withstand Current | 20kA/2s, 25kA/2s, 31.5kA/2s (optional) | |
| | Contact Resistance | ≤50μΩ | |
| Structural and Material Parameters | Main Body Material | Epoxy resin (insulation layer), copper/aluminum tin-plated (conductive inserts) |
| | Protection Rating | IP67 | |
| | Interface Standard | Inner tapered interface complying with GB/T 12706 and IEC 60840 standards | |
| | Specification Series | 1#, 2#, 3# (adaptable to different voltage/current ratings) | |
| Environmental Parameters | Applicable Altitude | ≤2000m (high-altitude customization available) |
| | Ambient Temperature | -40°C to +90°C (operating temperature), -40°C to +70°C (storage temperature) | |
| | Relative Humidity | ≤100% (non-condensing) | |
| | Seismic Resistance Rating | Grade 8 | |
| Applicable Standards | GB/T 12706, IEC 60840, GB/T 11022, DL/T 404 |
Applications
Applicable Voltage Ratings: 10kV/20kV AC medium-voltage power distribution systems, compatible with distribution equipment having maximum operating voltages of 17.5kV/25.2kV.
Applicable Equipment and Scenarios:
Cable inlet/outlet interfaces for 10kV/24kV ring main units, switchgear, pad-mounted transformers, American-style transformers, and other distribution equipment, serving as connection bases for inner tapered cable accessories;
Used in conjunction with inner tapered elbow cable connectors, surge arresters, and insulating caps to form complete separable cable terminals and surge arrester interfaces;
Urban distribution network cable circuits, industrial and mining enterprise power distribution systems, new energy (photovoltaic/wind power) step-up substation distribution equipment interfaces;
Interface installation for indoor/outdoor distribution rooms, underground utility tunnels, cable tunnels, and other multi-scenario distribution equipment.
Functional Purpose: Serves as an integrated insulated connection base between distribution equipment and inner tapered cable accessories, providing insulation, sealing, conduction, and mechanical support connections, delivering safe and reliable cable interface solutions for medium-voltage power distribution systems.
Operating Conditions
Normal Operating Conditions
Altitude: ≤2000m;
Ambient temperature: -40°C to +90°C, equipment operating temperature compliant with relevant standards;
Relative humidity: ≤100% (non-condensing);
Environmental conditions: no corrosive gases, no flammable or explosive media, no severe vibration or shock;
Installation method: flange-fixed mounting to equipment enclosure; horizontal or vertical installation acceptable; installation space must meet accessory mating operation requirements.
Special Operating Conditions (Customization Required)
Altitude exceeding 2000m;
Ambient temperature outside the range of -40°C to +90°C;
Severely polluted, salt spray, or chemically corrosive environments;
High vibration or high shock conditions;
Non-standard flange mounting hole patterns or special interface specifications;
Special grounding requirements or high pollution level applications.
Installation and Maintenance
Installation Requirements
Prior to installation, inspect the product appearance for cracks, damage, and voids; verify that the insulation surface is undamaged and the conductive inserts are intact, free of corrosion and deformation.
Clean the equipment enclosure mounting surface by removing oil, dust, and foreign matter; ensure the mounting surface is flat and clean; install the sealing gasket to ensure reliable flange face sealing.
Align the sleeve flange with the equipment enclosure mounting holes and tighten with the supplied bolts to the specified torque to prevent loosening that could cause seal failure or poor contact.
Apply a uniform coat of dedicated silicone grease lubricant to the inner wall of the sleeve’s inner tapered interface before installing the matching inner tapered cable accessories; ensure accessories are fully seated and engage the anti-withdrawal locking device.
After installation, perform insulation resistance testing and power frequency withstand voltage testing; the unit may be energized only after passing these tests.
Maintenance Requirements
Periodically inspect the sleeve appearance for cracks, discharge marks, and contamination accumulation; verify flange connection bolts are not loose and seals are free of aging or damage.
Periodically test insulation resistance to verify performance compliance and promptly identify potential faults.
Clean the sleeve surface by removing dust and contamination; maintain the insulation surface dry and clean; prevent contamination by oil or chemical substances.
If cracks, damage, discharge, overheating, or other abnormalities occur on the sleeve or associated accessories, immediately de-energize and replace; continued operation in a degraded condition is strictly prohibited.
Insertion and withdrawal of associated accessories must be performed using dedicated insulated operating tools; bare-hand operation of energized connectors is strictly prohibited; all operations must strictly comply with power distribution safety regulations.
Precautions
The product must be installed, commissioned, and maintained by qualified electrical personnel holding medium-voltage distribution construction credentials; operation by unqualified personnel is strictly prohibited.
The product must be used with inner tapered cable accessories of the corresponding specification; pairing with accessories of different voltage or current ratings is strictly prohibited, as this will cause insulation failure and safety incidents.
The sleeve must not be disassembled or modified without authorization, as doing so will void the warranty and safety assurance; use of non-dedicated tools to forcibly install or remove accessories is strictly prohibited.
Flange mounting bolts must be tightened to the specified torque to prevent loosening that could cause seal failure or poor contact and affect safe equipment operation.
Store in a dry, ventilated, cool environment away from direct sunlight, high temperatures, humidity, and compression; contact with sharp objects that could damage the insulation layer is strictly prohibited.
When performing live-line operations on associated accessories, strictly comply with power distribution safety regulations, implement proper safety protective measures, and avoid any unauthorized operations.
Model Designation
| Model Designation | Description |
|---|---|
| 1#/2#/3# | Specification series codes, adaptable to distribution equipment and cable accessories of different voltage and current ratings respectively |
| Inner Tapered Insulation Sleeves | Inner tapered insulation sleeves cast from epoxy resin, serving as connection bases for inner tapered cable accessories |
Applicable Standards and Certifications
International Standard: IEC 60840 “Power cables with extruded insulation and their accessories for rated voltages above 30kV (Um=36kV) up to 150kV (Um=170kV) — Test methods and requirements”;
National Standards: GB/T 12706 “Power cables with extruded insulation and their accessories for rated voltages from 1kV (Um=1.2kV) up to 35kV (Um=40.5kV)”, GB/T 11022 “Common specifications for high-voltage switchgear and controlgear standards”, DL/T 404 “3.6kV~40.5kV AC metal-enclosed switchgear and controlgear”;
The product has passed type testing by the National High-Voltage Electrical Apparatus Quality Supervision and Inspection Center and complies with national electrical safety standards.
After-Sales Service
Product warranty period: 18 months from the date of delivery from the factory, or 12 months from the date of commissioning, whichever comes first;
Free repair or replacement for quality-related issues within the warranty period;
Technical support, installation guidance, and customization services (special specifications, special operating condition adaptation) are provided.
Documentation Notice
The technical parameters in this manual are based on standard operating conditions. Special operating conditions require customization based on actual requirements; the product technical agreement and type test report shall prevail as the final reference.
Appendix: Product Outline Diagram
