Common knowledge about the maximum temperature rise of tubular busbars

The ultimate temperature rise is an important technical parameter for the evaluation of tubular busbars, which has attracted the attention of the design, supervision, construction, and acceptance units of Party A. As engineers, we must fully understand the concept of extreme temperature rise to avoid accidents.

According to the manufacturer of tubular busbars, the maximum temperature rise of tubular busbars refers to the temperature rise obtained by subtracting the ambient temperature from the stable temperature during full load operation of the rated current, usually expressed in K. The temperature rise limit test will be conducted during the busbar design period. The increase in temperature limits the current carrying capacity of the bus. An increase in temperature will shorten the lifespan of the bus, increase power loss, and reduce voltage. At the same time, it will also affect the ambient temperature, accelerate the aging of insulation materials in surrounding equipment, and even cause safety accidents.

In China, fire accidents caused by electricity account for over 60% of the total number of fire accidents. Fire accidents caused by electricity include cables, wires, high and low voltage equipment, transformers, tubular busbars, electrical components, etc. Most fire accidents are caused by insulation materials aging and short circuits due to long-term heating and overheating.

The ultimate temperature rise can be said to be a key safety technical parameter of tubular busbars and an important indicator reflecting overall performance. Users can also understand the following issues: purity of copper rod: The copper content is directly related to the resistivity of the conductor. The higher the resistivity of the same conductor specification, the higher the temperature rise. Conductor cross-sectional area: Under the same structure and process, as well as the same copper content, the cross-sectional area of the conductor is smaller, and the temperature rise is naturally higher.

Product Features:

The copper busbar with high current carrying capacity is a hollow conductor with a large surface area and uniform electric field distribution

Low skin effect, low power loss. Insulated copper tube busbar has a low skin effect coefficient (KF ≤ 1) and low AC resistance, which can reduce the power loss of the busbar

Good heat dissipation conditions, low temperature rise. The copper tube busbar is a hollow conductor with good heat dissipation conditions. The inner diameter air duct of the busbar can naturally form air convection (there is a pressure difference between the inside and outside of the tube)

The allowable stress' σ 'is large and the mechanical strength is high. The allowable stress of copper tube busbars is 4 times that of rectangular busbars. The short-circuit current that can be borne by the operating load is large, and the mechanical strength is high, which increases the support span of the busbar and reduces the corresponding pillar insulators, busbar fittings, and civil structure foundation area

The electrical insulation performance is strong. The insulated copper tube busbar adopts a multi-layer sealed shielding insulation method, and the shell is grounded with a potential of zero. Make the electric field distribution uniform, control the potential and limit the electric field; Characteristics such as avoiding partial discharge on insulation surfaces, conducting leakage and charging currents, and protecting against dangerous contact voltages

The insulation material used for insulated copper tube busbars has a high temperature coefficient, and the main insulation material is suitable for working in temperatures ranging from -250 ℃ to+250 ℃. It has excellent electrical performance and chemical stability, low dielectric loss, flame retardancy, aging resistance, and long service life

Strong resistance to electrical vibrations, directly fixing copper tube busbars on steel frames or concrete supports, eliminating wall bushings and post insulators, and possessing strong seismic resistance

Not affected by environmental interference, highly reliable insulated copper tube busbar is shielded and sealed, with no condensation generated inside and free from grounding and phase to phase short circuit faults caused by external moisture, dust, and foreign objects. The operation has a high degree of reliability. Compared with the same period last year, rectangular busbars exposed to the environment are prone to grounding and short circuit caused by accidental contact with people, animals, and other objects, which is not conducive to safe operation

The temperature rise at the connection point of the insulated copper tube busbar is lower than that of the conductor

Copper tube busbar structure is concise, arranged clearly, easy to install, and maintenance free

A tubular conductor is an air core conductor with a small skin effect coefficient and is beneficial for increasing the initial voltage of corona discharge. Outdoor power distribution equipment uses tubular conductors, which have the advantages of small footprint, concise structure, and clear layout.

Has the following characteristics:

Large current carrying capacity

The main body of the tubular busbar is a hollow copper tube or aluminum alloy tube with a large surface area. Compared to conventional rectangular busbars, the current density distribution on the conductor surface is uniform, and the rated current can reach 12000A.

Good insulation performance

The tubular busbar adopts a sealed shielding insulation method, and the grounding potential of the shell is zero. The electric field distribution on the surface of the busbar is uniform, and the electrical insulation performance is strong. It can be directly accessed through cable trenches and cable interlayers.

Good heat dissipation and low temperature rise

The tubular busbar is a hollow conductor with ventilation holes at both ends. The inner diameter air duct can naturally form hot air convection, providing better heat dissipation conditions compared to conventional busbars.

low loss

The shape of the tubular busbar determines its low surface skin effect coefficient, Kf≦1， The communication resistance is small, so the power loss of the busbar is small. The dielectric loss of the cross-linked shielding insulation tubular busbar insulation layer is less than 0.01%.

The insulation material has a high heat resistance coefficient

The main insulation material of the cross-linked shielded insulated tubular busbar is polytetrafluoroethylene, which has excellent electrical performance and chemical stability. It can work normally in temperatures ranging from -200 ℃ to+200 ℃, with low dielectric loss, flame retardancy, aging resistance, and can be used in conjunction with other insulation materials. The product has a service life of ≥ 20 years.

Strong resistance to electrical vibrations

The results of the dynamic stability test show that a copper tube bus with a voltage of 10kV and a rated current of 4000A can withstand a short-circuit current surge of 63kA (4s). The busbars can be directly fixed on steel frames or concrete supports, eliminating the need for wall sleeves and post insulators, and have strong anti vibration capabilities.

Not affected by environmental interference, high reliability

Each phase of the tubular busbar is enclosed shielded and insulated, with no condensation generated inside. It also has high reliability in operation due to grounding and phase to phase short circuit faults caused by external moisture, dust, and foreign objects.

Performance:
1. The busbar trunking that supports bare busbars (in low current situations, I ≤ 400A) or busbars coated with insulation layers on the surface (in high current situations, I>400A) inside the shell with insulation pads and insulated by air medium is called an air type busbar trunking.
2. The enclosed shell is made of steel and has undergone acid washing, phosphating, electroplating, and spraying on the surface. It has the characteristics of good performance and long service life, with a protection level of IP43 or above. The shell is grounded, convenient, reliable, and safe, and the continuity test of the protection test is qualified.
3. The conductor busbar conforms to the reasonable structure of GB5585.1-GB5585.3-85 insulation bolts to ensure low joint temperature rise, reliable and safe long-term use.
4. The surface of the busbar is coated with different insulation materials, which are suitable for various occasions.
5. Reasonable structure, good electrical and mechanical performance, and a complete range of functional units.

It is necessary to ensure that the connection is more suitable and reasonable, which helps to achieve useful assurance about the overall power distribution function. Bus ducts have indeed demonstrated a relatively ambitious connection flexibility in detailed application, without severe bundling, and can be effectively equipped according to the requirements of detailed industrial plant power distribution engineering, while also avoiding connection problems. The detailed application of bus ducts at that time was able to utilize 18 functional units for flexible arrangement, and the connection method showed stronger adaptability. Of course, the use of busbar trunking in industrial plant power distribution engineering also requires detailed attention to the detailed length of the busbar trunking, combined with detailed requirements for detailed analysis, to ensure that the corresponding use of busbar trunking can meet the application needs of the entire power distribution project in all aspects.