Inner Taper Insulation Plugs
Section I. Product Overview
Inner Cone Insulating Plugs are inner-taper-type insulating sealing components designed specifically for 10kV/35kV medium- and high-voltage power distribution systems. Featuring an inner taper plug-in/pull-out structure, they are compatible for direct use with 1#/2#/3# inner taper insulating sockets to seal unused inner taper interfaces, achieving insulation isolation, sealing protection, and safety grounding. They prevent electrical shock and flashover risks caused by exposed interfaces, and serve as critical safety protection accessories for power distribution equipment interfaces.
Section II. Product Features
Electrical and Insulation Performance
Manufactured via integral injection molding using high-purity silicone rubber with no seams or air gaps, providing excellent insulation performance capable of withstanding rated voltages and short-term overvoltages in 10kV/35kV systems, with sufficient insulation margin and partial discharge level ≤10pC (at 1.5U₀).
An integrated electric field optimization structure uniformly distributes the electric field at the interface, effectively suppressing partial discharge. Long-term operation presents no risk of electrical erosion or breakdown, ensuring stable and reliable insulation performance.
An integrated grounding insert provides reliable grounding, effectively dissipating interface-induced voltages and fault currents to enhance system safety.
The insulating surface is treated using a specialized process to achieve high surface resistivity and strong hydrophobicity, effectively preventing surface flashover caused by condensation or contamination, and improving insulation reliability in harsh environments.
Structural and Safety Features
Standardized inner taper plug-in/pull-out interface design strictly conforms to GB/T 12706 and IEC 60840 standards, offering universal interchangeability with 1#/2#/3# inner taper insulating sockets with strong compatibility, adapting to distribution equipment interfaces of various specifications.
The one-piece structural design allows direct insertion into the mating socket to achieve interface insulation sealing — no additional tools are required, installation is straightforward, and live-line operation is possible.
Anti-misinsertion and anti-misconnection design ensures interface dimensions are uniquely matched, permitting connection only to the corresponding specification socket to prevent cross-use of accessories of different specifications. An integrated positioning lock structure prevents loosening and disengagement after installation.
The fully insulated, touchable structure features high outer insulation strength, allowing the housing to be touched directly during operation without risk of electric shock, ensuring the safety of operations and maintenance personnel.
Environmental and Weather Resistance Performance
Excellent weather resistance adaptable to wide-temperature environments from -40°C to +90°C, with no degradation in rubber elasticity or insulation performance at high or low temperatures, and no risk of cracking or embrittlement, suitable for both outdoor and indoor applications.
Moisture-proof, waterproof, pollution-resistant, and salt-fog resistant with IP67 protection rating, enabling long-term stable operation in harsh environments including humid, dusty, and salt-fog conditions, resistant to rain and condensation ingress.
Anti-aging, UV-resistant, and ozone-corrosion resistant, with a service life exceeding 30 years, maintenance-free operation, and reduced long-term operations 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, with no risk of deformation or damage, and a seismic resistance rating of Grade 8.
Available in three sizes — 1#/2#/3# — compatible with inner taper insulating sockets of different voltage and current ratings, offering broad versatility.
Modular design allows individual plug-in/pull-out replacement; interface sealing or opening can be performed without de-energization, significantly improving operations and maintenance efficiency and reducing outage losses.
Section III. Technical Parameters
| Parameter Category | Item | Technical Specification |
| Applicable System Parameters | Rated System Voltage (Un) | 10kV/35kV |
| | Rated Voltage (Ue) | 12kV/35kV | |
| | Maximum Operating Voltage (Um) | 17.5kV/40.5kV | |
| | Rated Frequency (fn) | 50Hz/60Hz | |
| | Power Frequency Withstand Voltage | 42kV/5min (12kV), 95kV/5min (35kV), no breakdown, no flashover | |
| | Lightning Impulse Withstand Voltage | 95kV (12kV peak), 200kV (35kV peak), no breakdown, no flashover | |
| | Partial Discharge Level | ≤10pC (at 1.5U₀) | |
| Structural and Material Parameters | Body Material | EPDM ethylene propylene diene monomer rubber (insulating layer); tin-plated copper/aluminum (grounding insert) |
| | Protection Rating | IP67 | |
| | Interface Standard | Inner taper interface conforming to GB/T 12706 and IEC 60840 standards | |
| | Size Series | 1#, 2#, 3# (compatible with sockets of different voltage/current ratings) | |
| | Mating Sockets | 1#/2#/3# inner taper insulating sockets | |
| 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 |
Section IV. Scope of Application
Applicable voltage levels: 10kV/35kV AC medium- and high-voltage power distribution systems, compatible with distribution equipment having a maximum operating voltage of 17.5kV/40.5kV.
Applicable equipment and scenarios:
Sealing of unused inner taper insulating socket interfaces in distribution equipment such as 10kV/35kV switchgear, ring main units, and compact substations;
Interface safety protection for urban distribution network cable lines, industrial and mining enterprise distribution systems, and distribution equipment at renewable energy (photovoltaic/wind power) step-up substations;
Interface insulation isolation for distribution equipment in indoor/outdoor distribution rooms, underground utility tunnels, cable tunnels, and other multi-scenario applications.
Functional purpose: To seal unused inner taper interfaces in distribution equipment, achieving insulation isolation, sealing protection, and safety grounding, preventing risks of electric shock, flashover, and moisture ingress caused by exposed interfaces, and ensuring the safe and stable operation of distribution equipment.
Section V. Operating Conditions
Normal Operating Conditions
Altitude: ≤2000m;
Ambient temperature: -40°C to +90°C, with equipment operating temperature conforming to relevant standards;
Relative humidity: ≤100% (non-condensing);
Environmental conditions: free from corrosive gases, flammable or explosive media, and severe vibration or shock;
Installation method: direct insertion into the mating inner taper insulating socket; both horizontal and vertical installation are acceptable, and the installation space must meet plug-in/pull-out operational clearance requirements.
Special Operating Conditions (Customization Required)
Altitude exceeding 2000m;
Ambient temperature outside the range of -40°C to +90°C;
Severe contamination, salt-fog, or chemical corrosion environments;
High-vibration or high-shock operating conditions;
Non-standard inner taper interface specifications;
Special grounding requirements or high pollution class applications.
Section VI. Installation and Maintenance
Installation Requirements
Before installation, inspect the product appearance for cracks, damage, and voids, and verify the insulating surface is undamaged; confirm that grounding inserts are intact with no corrosion or deformation.
Clean the inner wall of the mating inner taper insulating socket and the plug surface, removing grease, dust, and foreign matter to ensure the interface is dry and clean.
Apply a uniform coat of dedicated silicone grease lubricant to the outer wall of the plug interface to prevent damage to the insulating layer during installation.
Slowly push the plug into the mating socket until fully seated; engage the positioning anti-withdrawal device; after installation, verify there is no looseness or tilting.
After installation, verify that the interface seal is reliable with no risk of air leakage or moisture ingress; perform an insulation resistance test if necessary, and commission only upon satisfactory results.
Maintenance Requirements
Periodically inspect the plug appearance for cracks, discharge marks, and contamination accumulation; verify that the connection to the socket is secure with no looseness, and that sealing components show no aging or damage.
Periodically test insulation resistance to confirm performance meets requirements and to identify potential faults in a timely manner.
Clean the plug surface to remove dust and contamination, keeping the insulating surface dry and clean, and avoiding exposure to grease and chemical corrosion.
If abnormalities such as cracks, damage, discharge, or overheating occur on the plug or mating socket, immediately take the unit out of service and replace it; continued operation with known defects is strictly prohibited.
Plug-in/pull-out operations must be performed using dedicated insulating operating tools; bare-hand contact with energized interfaces is strictly prohibited, and all operations must strictly comply with power distribution safety regulations.
Section VII. Precautions
The product must be installed, commissioned, and maintained by qualified electrical personnel holding medium- and high-voltage distribution construction credentials; operation by unqualified personnel is strictly prohibited.
The product must be used only with the corresponding specification of inner taper insulating socket; cross-matching with sockets of different voltage levels or different specifications is strictly prohibited, as this will result in insulation failure and safety incidents.
The plug must not be disassembled or modified without authorization, as this will void the warranty and safety assurance; forced installation or removal using non-dedicated tools is strictly prohibited.
During installation, damage to the insulating surface is strictly prohibited; silicone grease lubricant must be applied uniformly to avoid compromising insulation performance and sealing effectiveness.
During storage, the product must be kept in a dry, ventilated, and cool environment, away from direct sunlight, high temperatures, humidity, and compression; contact with sharp objects that could damage the insulating layer is strictly prohibited.
When performing plug-in/pull-out operations on energized interfaces, all power distribution safety regulations must be strictly observed and adequate safety protective measures must be in place; unauthorized operations are strictly prohibited.
Section VIII. Model Designation
| Model Designation | Description |
| 1#/2#/3# | Size series designator, compatible with inner taper insulating sockets of different voltage and current ratings respectively |
| Inner Taper Insulation Plugs | Inner taper insulation plug, integrally injection-molded from EPDM rubber, used for insulation sealing and safety protection of inner taper interfaces |
Section IX. 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) 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 conforms to national electrical safety standards.
Section X. After-Sales Service
Product warranty period: 18 months from the date of manufacture, or 12 months from the date of commissioning, whichever comes first;
Free repair or replacement for product quality issues during the warranty period;
Technical support, installation guidance, and customization services (special specifications, special operating condition adaptations) are available.
Documentation Notes
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.
Appendix: Product Outline Drawing
