To clarify the difference between compact busbar trunking systems and air-insulated busbar trunking systems, we recommend first reviewing the professional specification definitions for common busbar trunking systems: The specification definition for compact busbar trunking systems is: “After covering exposed busbars with insulating materials, they are placed close to the enclosure of the duct.” The specification definition for air-insulated busbar trunking systems is: “The busbars are supported within the enclosure by insulating spacers and insulated by an air dielectric layer.”

The performance characteristics of the two types differ: In terms of manufacturing, the compact insulated busbar trunking is more complex to produce; from a safety perspective, it has higher insulation requirements. Compact insulated busbars offer advantages such as high current-carrying capacity, enhanced safety and energy efficiency, excellent dynamic thermal stability, compact size, good heat dissipation, and low temperature rise—making them well-suited for high-power current transmission. On the other hand, air-insulated busbar trunking has a relatively simpler manufacturing process. In terms of safety performance, its insulation requirements are lower than those of compact insulated busbar trunking, and its insulation method is more flexible (either encapsulated or non-encapsulated), facilitating tap-offs. However, its drawbacks include poor current-carrying capacity, significant temperature rise, high impedance, poor heat dissipation, and incompatibility with high-current applications.

The difference in current-carrying capacity between the two types: Current-carrying capacity is an important indicator for evaluating waterproof busbar trunking products. Current-carrying capacity refers to the current that flows through the busbar trunking during power transmission. Under thermal stability conditions, when the busbar conductor reaches its long-term permissible operating temperature, the current-carrying capacity of the waterproof busbar trunking is referred to as its long-term permissible current-carrying capacity. A large body of experimental data shows that the current-carrying capacity of compact waterproof busbar trunking is superior to that of air-insulated busbar trunking—meaning that, for conductors of the same specifications, the current ratings can differ by one or more levels. The primary reason for the inferior current-carrying capacity of air-insulated busbars is their higher impedance, which leads to greater power losses and poorer heat dissipation, a problem that becomes particularly pronounced in high-current air-insulated busbars. For example, in a 4000A compact waterproof busbar trunking, the current density is approximately 1.8 A/mm²; whereas in an air-insulated busbar trunking, the current density can reach only about 1.2 A/mm². By selecting waterproof busbar trunking appropriately, we can significantly enhance the safety and reliability of power transmission and distribution systems. Given the distinct characteristics of compact and air-type busbar trunkings, it is recommended to choose compact waterproof busbar trunking for main lines, feeder sections of distribution systems, and buildings with high current ratings. This practical invention boasts a large current-carrying capacity, low power loss, balanced reactance, and ease of use, effectively reducing electricity consumption costs.

According to their insulation method, busbar trunking systems can be classified into air-insulated busbar trunking systems, compact-insulated busbar trunking systems, and high-strength busbar trunking systems.

1. Different insulation methods:

The busbars in the air-insulated busbar trunking system are spaced apart to maintain inter-phase insulation; therefore, the insulating medium of the air-insulated busbar trunking system is air.

The copper busbars in a compact busbar trunking system are wrapped with an insulating medium and then arranged closely together without any gaps. The insulating medium used in compact busbar trunking systems is an organic insulating material.

2. Different structures:

Due to the spacing between air busbars, the volume of waterproof busbars is relatively large. In contrast, compact busbar systems have a dense structure and a small volume.

3. Different heating methods:

Air-type busbars allow the air inside the waterproof busbar to convect with the outside environment through ventilation holes on the enclosure, thereby dissipating the heat generated by the busbar. However, this design has low heat dissipation efficiency.

The compact busbar system dissipates heat directly through its enclosure, resulting in a high heat dissipation rate.

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