Conduit Busbar_Machinery_Products_Zhongshang 114 Industry Resources Network

I. Overview

With the rapid and steady growth of the national economy and the explosive development of urban construction, the electricity consumption of enterprises and residents has soared, leading to a continuous increase in the main transformer capacity of sub-stations. Consequently, the rated current on the low-voltage output side of transformers has also risen, making it increasingly necessary for the power department to find a conductive product with a high current-carrying capacity and safety factor to replace the existing rectangular busbars. On this premise, our technical staff and some cable manufacturing experts innovated a new conductive product, the tubular busbar, in 2003, referencing the insulation structure of cross-linked cables. This product has been applied in actual projects and has achieved excellent results, playing a positive role in ensuring the safe operation of sub-stations, improving the reliability of power supply, and reducing energy losses.

Section 2: The advantages of tubular busbars compared to conventional rectangular busbars include:

a) Low skin effect, high current density per unit cross-section, tubular busbars mainly use copper tubes as the main conductor. The outer surface of the copper tube is circular, with even charge distribution. Unlike rectangular busbars with sharp edges, surface charges do not accumulate at the corners, thus preventing localized overheating and energy waste. Additionally, the copper tube is a hollow conductor with a low skin effect and higher current density per unit cross-section than conventional rectangular busbars. For instance, a copper tube conductor of 100x5 has a cross-sectional area of 1491.5 m², capable of carrying a current of 3150A, with a current density of 2.11A/mm² and a temperature rise of <45K. In contrast, a rectangular busbar carrying 3150A would require two 120x0 copper busbars, resulting in a current density of 1.3A/mm² with a temperature rise of approximately 70K.

b) For most conductive products, overheating is to be avoided. Tubular busbars, made primarily of steel pipes, have a hollow center, allowing for air convection within the conductor, thus offering good heat dissipation. This is an effect that conventional rectangular busbars and cables cannot achieve.

c) Allowing for high stress, large spans, and high mechanical strength, we learned from the electrical engineer's handbook on conductive materials that copper tubes have a stress of 294MPa and a tensile strength of 320MPa, which is four times that of rectangular copper busbars. This enables the tubular busbars to withstand far greater short-circuit electrical forces than rectangular busbars. The span of the busbar can reach 9 meters, and with a double steel frame structure for support, it can extend to 14 meters, allowing direct entry into the high-voltage room to connect with switchgear or reactors, reducing the need for conventional busbar支柱insulators, busbar fittings, and civil engineering. Moreover, the use of a steel frame structure for the busbar support enhances its seismic resistance.

d) The insulation of the main busbar, featuring strong electrical insulation properties and stability of the main insulation materials, is a multi-layered insulation structure formed by alternating multiple insulation materials and shielding materials. The potential decreases layer by layer from the inside to the outside, reaching zero at the surface. Multiple shielding layers ensure a uniform charge distribution on the surface of each insulation layer, preventing local discharges on the insulation surface and interference from the electric field and magnetic field of other phase busbars. Additionally, the main insulation material, polytetrafluoroethylene, offers excellent electrical and chemical stability, low dielectric loss, flame retardancy, aging resistance, and a long service life.

e) Busbar structure is simple, clear, well-arranged, easy to install, and requires minimal maintenance.

Section 3: Tubular Busbar Models Introduction

0.4KV Low-Voltage Tubular Busbar Specifications and Models

Standard Full-Insulated

2. Metal-clad full-insulated

6KV, 10KV Tubular Busbar Specifications and Models

Pillar-shaped busbar (suitable for outdoor overhead use)

2. Segmented shielded busbar (suitable for outdoor overhead and reactor rooms)

3. Full-shielded tubular busbars are suitable for high-voltage rooms with cable trenches and cable layers.

Typical Application Scheme for Tubular Insulated Busbars

Option 1: Main transformer to control room connection

This is a common method for applying busbar conduit, with the busbar directly connected from the low-voltage terminal of the main transformer to the switchgear terminal in the control room. Key advantages: suitable for high currents, clear and aesthetically pleasing wiring, and available in both full insulation and semi-insulation options.

Option 2: Busbar routed through cable trench or cable tray area

The image below shows another common application of busbars in conduit form. The busbar can be connected through underground cable trenches or cable chambers to switch cabinets, and it can also be used for connections between switch cabinets. This busbar is of full-insulated type, particularly suitable for difficult wiring scenarios.

Method 3: Conductor busbars run through cable trenches or cable mezzanines.

This method involves connecting the overhead line at the top of the switchgear, or it can also be done through the cable tray using the bottom entry line. Users can choose according to their specific circumstances. The busbar type is fully insulated.