This product is the TG3-24Q/175×235×278 Wall-Throught Bushing , which is an indoor high-voltage insulation component designed specifically for medium-voltage power distribution systems. It is made of high-quality epoxy resin and integrally molded using the APG (Automatic Pressure Gel) process, possessing excellent electrical insulation performance, mechanical strength, and environmental adaptability.
through-wall insulation and mechanical support for conductive busbars/cables in high-voltage switchgear , while also achieving electrical separation between different compartments. It is widely used in 24kV medium-voltage switchgear, ring main units and other switchgear.
Total height of the sleeve (total length above and below the flange, unit: mm)
2. Structural Features
Overall structure : It has a square mounting flange in the middle, and umbrella-shaped insulating bodies at the top and bottom. The inner hole is an elliptical/rectangular through hole to accommodate copper/aluminum busbars.
Umbrella skirt design : The upper and lower ends have multiple umbrella skirt structures, which increase the creepage distance, improve the surface insulation performance, and effectively suppress pollution flashover and wet flashover.
Flange design : Square mounting flange with pre-drilled standard mounting holes for easy fixing on switch cabinet partitions, ensuring installation sealing and mechanical strength.
Material characteristics : The epoxy resin is integrally cast, without bubbles or cracks, with uniform insulation performance, high mechanical strength, and resistance to aging and electric arc.
III. Core Technical Parameters
1. Electrical parameters
Parameter Items
Indicator Requirements
Rated voltage (Un)
24kV
Rated frequency (fn)
50/60Hz (Applicable to 15~60Hz AC systems)
Rated lightning impulse withstand voltage (peak value)
125kV
Rated power frequency withstand voltage (1 min, RMS value)
65kV
Partial discharge quantity
≤5pC (tested at 1.05Un)
creepage distance
≥630mm (meets the 24kV indoor pollution level requirements)
Applicable rated current
2000A~4000A (matching busbar specifications)
Insulation resistance
≥1×10¹²Ω
2. Mechanical and physical parameters
Parameter Items
Indicator Requirements
Material
Epoxy resin (EPOXY), with added flame retardants
color
Standard reddish-brown (customizable)
Total height
278mm
Inner hole size
175mm×235mm (suitable for corresponding busbar specifications)
Flange dimensions
Standard size 255×255mm (customizable)
Bending failure load
≥8kN
Tensile failure load
≥6kN
Flame retardant rating
V-0 rating (UL94 standard)
Temperature resistance rating
Class F (long-term operation at -40℃ to +120℃)
density
≥1.95g/cm³
Shore hardness
≥85 Shore D
3. Dimensional parameters (for reference)
Part
Dimensions (mm)
Total height
278
Inner hole length × width
175×235
Flange side length
255 (Standard)
Flange thickness
20 (Standard)
Umbrella skirt outer diameter
Adapted to 24kV insulation requirements, standard design.
IV. Product Characteristics
1. Excellent electrical performance
It uses a high-purity epoxy resin formula, which has high insulation strength, extremely low partial discharge, and no risk of insulation aging during long-term operation.
The umbrella skirt structure is optimized with sufficient creepage distance, effectively resisting surface discharge in humid and dirty environments.
It has excellent resistance to electric arc and corona, and can withstand system overvoltage impacts, ensuring safe operation of equipment.
2. Reliable mechanical properties
It is integrally cast, with high structural strength, excellent resistance to bending, tension and impact, and can withstand the installation stress and operation vibration of the busbar.
The flange is integrated with the main body, with no splicing gaps, and has good sealing performance after installation, preventing moisture and dust from entering the cabinet.
It features high dimensional accuracy, strong interchangeability, and compatibility with the installation requirements of mainstream 24kV medium-voltage switchgear and armored withdrawable switchgear.
3. Strong environmental adaptability
It is resistant to high and low temperatures, damp heat, and aging, and can operate stably for a long time in environments ranging from -40℃ to +120℃, adapting to different climate regions in China.
With flame retardant performance reaching V-0 level, it is self-extinguishing upon contact with fire and does not support combustion, thus improving the fire safety of the switch cabinet.
It is resistant to chemical corrosion, oil, and ozone, making it suitable for complex environments such as industrial power distribution.
4. Easy installation and maintenance
The standardized design allows for direct installation onto the switchgear partition without the need for additional insulation, resulting in high installation efficiency.
With its maintenance-free design, it requires no regular maintenance during operation; only periodic cleaning of surface dirt is needed.
Size, color, and mounting hole positions can be customized according to user needs to adapt to special cabinet requirements.
V. Scope of Application
1. Applicable Scenarios
A three-phase AC indoor power distribution system with a rated voltage of 24kV (10~35kV compatible) and a frequency of 50/60Hz.
Complete sets of equipment including 24kV armored withdrawable switchgear (KYN28A-24, etc.), ring main units, prefabricated substations, and high-voltage switchgear.
Power distribution equipment for power plants, substations, industrial power distribution rooms, and new energy power plants (photovoltaic, wind power), etc.
Insulation and fixed connection of conductive busbars/cables when passing through switch cabinet partitions, walls, and grounding objects.
2. Compatible busbar specifications
With an inner diameter of 175×235mm, it is compatible with copper/aluminum busbars of corresponding sizes and can meet the high current distribution requirements of 2000A~4000A.
VI. Usage Conditions
1. Normal operating conditions
Ambient temperature: -40℃ to +40℃, with the daily average temperature not exceeding +35℃.
Altitude: Not exceeding 1000m (when the altitude exceeds 1000m, altitude correction shall be made in accordance with GB/T 11022).
Ambient humidity: Daily average relative humidity not exceeding 95%, and monthly average relative humidity not exceeding 90%.
Environmental conditions: For indoor use, free from severe pollution, corrosive gases, flammable and explosive media, and severe vibration and impact.
Installation location: Vertical or horizontal installation, with an inclination angle not exceeding 15°.
2. Special usage conditions (customization required)
High-altitude areas (>1000m): Increased creepage distance is required, and customized high-altitude products are needed.
In areas with high pollution and high humidity: the number of umbrella skirts needs to be increased to improve anti-pollution flashover performance.
Special temperatures and special installation scenarios: Product parameters can be customized according to user needs.
VII. Installation and Maintenance Requirements
1. Installation Requirements
Pre-installation inspection: Confirm that the bushing is free of cracks, bubbles, and damage, that its dimensions meet the drawing requirements, and that the insulation resistance test is qualified.
Installation method: Pass the bushing through the switch cabinet partition and fix the flange with bolts, ensuring that the flange fits tightly with the partition without any looseness.
Busbar insertion: The busbar is inserted into the inner hole of the bushing. A uniform gap should be reserved between the busbar and the inner wall of the bushing to avoid squeezing the bushing and causing insulation damage.
Sealing treatment: A sealing gasket can be installed between the flange and the partition to improve the sealing performance of the cabinet and prevent moisture and dust from entering.
Post-installation testing: After installation, conduct power frequency withstand voltage and partial discharge tests to confirm that the insulation performance is qualified before putting it into operation.
2. Maintenance Requirements
Routine maintenance: Regularly inspect the appearance of the sleeve, clean the surface dust and dirt, and keep the skirt clean and dry.
Regular testing: Insulation resistance and power frequency withstand voltage tests should be conducted every 1 to 3 years to confirm that the insulation performance meets the requirements.
Abnormal handling: If any abnormalities are found on the bushing surface, such as cracks, discharge marks, or decreased insulation resistance, power should be cut off immediately and the bushing replaced. Operation with defects is prohibited.
VIII. Implementation Standards and Certification
The applicable standards are: GB/T 12944.1 “High-voltage wall bushings – Part 1: Porcelain bushings and glass fiber bushings”, GB/T 11022 “Common technical requirements for high-voltage switchgear and controlgear standards”, DL/T 486 “AC high-voltage disconnecting switches and grounding switches”, etc.
Product Certification: Tested by the National High Voltage Electrical Appliances Quality Supervision and Inspection Center and meets 3C certification requirements (if required).
IX. Packaging, Transportation and Storage
1. Packaging
The packaging uses cardboard boxes and foam cushioning to prevent damage caused by collisions and squeezing during transportation.
The package includes a product certificate, test report, and installation instructions.
2. Transportation
Avoid violent vibrations, rain, and sun exposure during transportation; do not throw, drop, or subject to heavy pressure.
It can be transported via conventional means such as road, rail, and sea.
3. Storage
Store in a dry, ventilated, and clean indoor environment, avoiding moisture, high temperatures, and corrosive gases.
Avoid heavy pressure when stacking to prevent deformation and damage to the casing. The storage period should not exceed 2 years.
X. Precautions
This product is for indoor use only and should not be used directly in outdoor environments.
Installation and maintenance must be performed by professional electrical personnel, and high-voltage electrical safety regulations must be strictly followed.
Drilling, cutting, or striking the surface of the sleeve is prohibited to avoid damaging the insulation structure.
If the product model or size does not meet your requirements, please contact the manufacturer for customization. Unauthorized modifications are prohibited.
If abnormal heating or discharge sounds occur during product operation, immediately stop the power and check. Operation can only be resumed after the fault has been eliminated.
