In modern high-rise buildings, subways, hospitals, data centers, and other places that require power supply safety, the stability and fire performance of power transmission systems are crucial. As an upgraded alternative to traditional cables, bus ducts are widely used in backbone distribution systems due to their advantages of high current carrying capacity, convenient installation, and simple maintenance. Among these key facilities, fire-resistant bus ducts play a vital role as the "lifeline" - they not only undertake the task of power transmission, but also provide continuous and stable power supply in the event of a fire, ensuring the normal operation of key facilities such as fire-fighting equipment, emergency lighting, and smoke exhaust systems, and buying valuable time for personnel evacuation and fire fighting.

1、 What is fire-resistant bus duct?

Fire resistant busbar trunking is a specially designed enclosed busbar system, whose core function is to maintain circuit integrity and power supply capacity for a certain period of time (such as 90 minutes, 180 minutes or even longer) under fire conditions, without interruption of operation due to high temperature, flames or smoke. The biggest difference between it and ordinary bus ducts or flame-retardant bus ducts is its fire resistance performance, which means that under standard fire test conditions (such as GB/T 19216, IEC 60331, etc.), it can withstand flame burning without losing insulation performance and mechanical strength.

2、 Structural characteristics and fire resistance principle:

1. Conductor: High purity electrolytic copper or aluminum is used to ensure good conductivity and current carrying capacity.

2. Insulation material: This is the key to fire resistance performance. Ordinary bus ducts often use organic materials such as polyester film or PVC, while fire-resistant bus ducts use inorganic insulation materials such as mica tape, ceramicized silicone rubber, mineral insulation (MI), etc. These materials will not burn, carbonize or release toxic gases at high temperatures, and can maintain good electrical insulation performance.

3. Shell: Usually made of high-strength cold-rolled steel plate or stainless steel, the surface is treated with fireproof coating or added with fireproof insulation layer (such as rock wool, aluminum silicate fiber, etc.) to delay the conduction of heat to the interior and protect the internal conductor and insulation layer.

4. Sealing structure: High temperature resistant sealing strips or fireproof mud are used to fill the joints and ends to prevent flames and smoke from entering.

The principle of fire resistance is that when a fire occurs, the external flame temperature can reach over 1000 ℃, and the outer shell and insulation layer of the fire-resistant bus duct first act as a physical barrier to slow down heat transfer; At the same time, the internal inorganic insulation material can maintain structural integrity at high temperatures, ensuring that the insulation between conductors and between conductors and the shell is not broken down, thereby ensuring continuous power transmission.

3、 Main performance indicators and standards:

-Fire resistance time: commonly 90 minutes (N3 level), 180 minutes (N2 level) or longer, meeting the requirements of different building fire protection levels.

-Voltage resistance level: usually 690V, 1000V or higher, suitable for different distribution systems.

-Current carrying capacity: ranging from several hundred amperes to several thousand amperes, to meet high-power electricity demand.

-Protection level: generally reaching IP54 or above, dustproof and waterproof, suitable for complex environments.

-Environmental performance: does not release toxic gases during combustion and complies with environmental standards such as RoHS.

The relevant standards include: GB 7251.6 "Low voltage switchgear and control equipment - Part 6: Busbar trunking systems (bus ducts)", GB/T 19216 "Integrity tests for cables or optical cable lines under flame conditions", etc.

4、 Application scenarios:

-High rise buildings: serving as the main power supply lines for fire elevators, emergency lighting, and smoke control systems.

-Hospital: Ensure uninterrupted power supply to key areas such as operating rooms and ICUs.

-Rail transit: emergency power supply system in subway stations and tunnels.

-Data center: Ensure the continuous operation of servers and network equipment in the event of a fire.

-Industrial plant: used for power distribution of key equipment such as fire pumps and alarm systems.