Product Overview
The TG3-24Q/175×255×310 Wall-Throught Bushing is an indoor epoxy resin insulating bushing designed for medium-voltage distribution systems rated at 24 kV and below.
Manufactured as an integrated structure using the APG pressure gelation process, it is used where high-voltage conductive busbars pass through switchgear partitions, walls, or other grounded structures. The product provides electrical insulation, mechanical support, and transitional busbar connection.
It is widely used in 24 kV withdrawable switchgear, ring main units, and other complete power distribution equipment.
Model Description
| Model Code | Description |
|---|---|
| TG3 | Epoxy resin wall bushing series for withdrawable switchgear |
| 24Q | Rated voltage of 24 kV; Q indicates a fully insulated or reinforced insulation structure |
| 175×255 | Inner opening dimensions for the busbar: 255 mm long and 175 mm wide, with an oval or rectangular opening |
| 310 | Overall bushing height, including the upper and lower sheds, 310 mm |
Product Features
Excellent Electrical Performance
- Manufactured from high-purity epoxy resin with high dielectric strength and low dielectric loss.
- Capable of withstanding the long-term operating voltage of a 24 kV system, as well as lightning impulse and power-frequency withstand voltage tests.
- The optimized shed structure increases the creepage distance and improves resistance to pollution flashover and moisture.
- Suitable for humid, dusty, and other demanding indoor environments.
- The fully insulated structure helps minimize partial discharge risks and supports safe and stable system operation.
Reliable Mechanical Performance
- The one-piece moulded structure provides high mechanical strength, impact resistance, and ageing resistance.
- Capable of withstanding busbar installation stress and vibration generated by the switchgear.
- The central square flange provides accurate installation positioning and reliable sealing.
- Effectively separates the internal and external spaces of the switchgear compartment.
- Lightweight construction with no risk of porcelain bushing explosion, helping improve equipment safety.
Reliable Manufacturing and Environmental Adaptability
- Manufactured using the APG pressure gelation process, providing a dense, uniform structure with no bubbles or cracks.
- High product consistency supports reliable batch installation and replacement.
- Flame-retardant performance complies with UL94 V-0.
- Resistant to high and low temperatures, chemical corrosion, and long-term ageing.
- Maintenance-free design requires only periodic cleaning of surface contamination.
Technical Specifications
| Parameter | Specification |
|---|---|
| Rated Voltage | 24 kV, suitable for 10–35 kV three-phase AC systems |
| Rated Frequency | 50/60 Hz; suitable for systems from 15 to 60 Hz |
| Rated Current | Suitable for 630–2,500 A busbar systems, depending on busbar specifications |
| Power-Frequency Withstand Voltage | Dry test: 65 kV for 1 minute; wet test: 50 kV for 1 minute |
| Lightning Impulse Withstand Voltage | 125 kV peak |
| Creepage Distance | ≥630 mm, meeting the insulation requirements of 24 kV systems |
| Inner Opening Dimensions | 175 × 255 mm, oval or rectangular |
| Overall Height | 310 mm |
| Flange Dimensions | Suitable for standard mounting holes in 24 kV withdrawable switchgear; customizable |
| Material | Epoxy resin with a red insulating housing |
| Operating Temperature Range | -40°C to +120°C for long-term operation |
| Flame-Retardant Rating | UL94 V-0 |
| Applicable Standards | GB/T 12944.1–12944.2 and IEC 60137 |
Applications
Typical Applications
- 24 kV indoor metal-clad withdrawable switchgear, including KYN28A-24 models.
- Ring main units, box-type substations, and busbar wall-passage insulation in distribution stations.
- Power stations and substations where live conductors pass through partitions or walls.
- Insulating support for conductive components in medium-voltage distribution equipment.
- Medium-voltage distribution systems in photovoltaic and wind power booster stations.
Compatible Busbars
The 175 × 255 mm inner opening is suitable for corresponding rectangular copper or aluminium busbars and can meet high-current transmission requirements.
Operating Conditions
Normal Operating Conditions
- Ambient temperature: -40°C to +40°C.
- Daily average temperature: no more than +35°C.
- Installation altitude: no more than 1,000 m.
- Customized high-altitude versions are available for installations from 1,000 to 4,000 m.
- Daily average relative humidity: no more than 95%.
- Monthly average relative humidity: no more than 90%.
- Indoor installation only.
- The operating environment should be free from severe pollution, corrosive gases, and flammable or explosive substances.
- Seismic intensity should not exceed Level 8.
- Severe vibration and mechanical impact should be avoided.
Special Operating Conditions
Customized products are required for:
- High-altitude environments.
- Heavily polluted or high-salt-spray environments.
- Extremely high or low temperatures.
- Special mounting dimensions.
- Configurations requiring an integrated shielding layer.
Installation and Maintenance
Installation Requirements
- Inspect the bushing before installation. Confirm that the surface is free from cracks, bubbles, mechanical damage, moisture, and contamination.
- Pass the busbar through the inner opening. Ensure that the busbar does not contact or press against the inner wall and that sufficient insulation clearance is maintained.
- Fit the flange closely against the switchgear partition and tighten the bolts evenly. Avoid localized stress that may cause cracking.
- After installation, inspect the insulation between the bushing and the switchgear enclosure and confirm that the grounding connection is reliable.
Maintenance Requirements
- Routine inspection: Check the surface for contamination, discharge marks, cracks, and damage. Confirm that the flange seal remains intact.
- Periodic cleaning: Clean the surface using a dry, soft cloth or anhydrous alcohol. Do not use corrosive cleaning agents.
- Preventive testing: Conduct insulation resistance and withstand voltage tests regularly in accordance with applicable electrical maintenance procedures.
Precautions
- Do not operate the bushing if it is damaged, damp, or severely contaminated.
- Avoid striking or colliding with the bushing during installation to prevent damage to the insulating structure.
- The bushing is intended for indoor use only and must not be installed directly in exposed outdoor environments.
- Confirm the busbar dimensions and switchgear mounting-hole positions before selecting the product to avoid mismatching.
- Protect the product from compression, moisture, high temperatures, and direct sunlight during transportation and storage.
Customization and Services
- Special dimensions, integrated shielding layers, high-altitude configurations, and other non-standard products can be customized according to project requirements.
- Technical support, installation guidance, and after-sales warranty services are available.
