Copper Flexible Busbars: Key Applications in Braking Resistor Cabinets and High-Voltage Grounding Circuits
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Xi’an, Shaanxi Province, China-October 22, 2026
During the operation of high‑speed EMUs, the release of electric braking energy, discharge of fault current and equipotential protection of the vehicle body are critical to the stable operation of the whole high‑voltage system. Braking resistor cabinets and high‑voltage grounding circuits are constantly subjected to pulsed heavy current, severe vibration, alternating temperature differences, as well as erosion from rain, snow, wind and sand. Direct connection via rigid copper bars easily generates mechanical stress due to thermal expansion, displacement and asynchronous vibration, which may result in base cracking, bolt loosening and rising contact resistance, bringing safety risks such as overheating, arcing and grounding failure. Focusing on high‑power flexible conductive solutions for rail transit, Xi’an Zipeng Technology’s self‑developed laminated copper foil flexible busbars have been stably supplied for braking resistor cabinets and high‑voltage grounding collection circuits of multiple EMU models.
The roof‑mounted braking resistor cabinet serves as the energy consumption unit for dynamic electric braking of EMUs. When the train decelerates, massive kinetic energy is converted into electric energy and dissipated as heat through braking resistors to prevent overvoltage of the catenary network. Braking resistors witness a sharp temperature rise during operation, and obvious thermal elongation occurs in resistor modules and ceramic supporting bases. Meanwhile, the roof area is exposed to high‑speed airflow, sunlight and condensation, accompanied by continuous vibration caused by turning and bumping of the train. If rigid copper bars are adopted, thrust generated by thermal expansion will pull the ceramic resistor bases directly. Under repeated long‑term stress, the bases are prone to cracking, leading to falling‑off of resistor elements and circuit disconnection. The large‑cross‑section copper flexible busbars supplied by Xi’an Zipeng Technology are integrally formed by diffusion welding of multiple layers of T2 copper foil with compact and non‑delaminated end faces. They maintain stable temperature rise under short‑time pulsed heavy current conditions and release assembly stress through flexible deformation to compensate the thermal elongation of resistors and protect resistor bases from tensile damage. The products are tinned for corrosion resistance and covered with high‑temperature resistant, low‑smoke and halogen‑free insulating sleeves to adapt to the harsh open‑air roof environment, and meet the requirements of short‑time withstand impulse current. They are widely applied in CRH380 and CR400 series for connections between roof braking resistor modules and between resistor banks and high‑voltage busbars.
High‑voltage grounding circuits undertake three core functions: equipotential bonding of the whole vehicle, rapid discharge of short‑circuit fault current and suppression of shaft current. The application scope covers vehicle grounding collector bars, bogie frames, gearboxes, axle box grounding jumpers and protective grounding points inside high‑voltage cabinets. Relative dynamic displacements such as floating, lateral swinging and deflection exist between the EMU carbody and bogies during operation, and different equipment bases vibrate at inconsistent frequencies, which cannot be accommodated by rigid conductors. Once the grounding link is disconnected, potential difference will form on the carbody and induce shaft current, resulting in galvanic corrosion and premature failure of bearings. In case of high‑voltage grounding faults, poor grounding paths will hinder rapid fault current discharge and expand the scope of failure impact. The customized copper flexible busbars developed by Xi’an Zipeng Technology for high‑voltage grounding circuits balance current‑carrying capacity and flexible deformation capability. They enable multi‑directional displacement compensation to keep grounding circuits continuously conductive and stabilize contact resistance, so that fault current can be quickly guided to the ground, eliminating carbody potential difference and protecting bearings and high‑voltage electrical components. Compared with ordinary copper braids, laminated copper flexible busbars feature stronger current‑carrying capacity and lower parasitic inductance, showing prominent advantages at high‑power protective grounding points.
Rail transit components require extremely high reliability. All rail‑transit‑grade copper flexible busbars from Xi’an Zipeng Technology are designed and manufactured in strict accordance with EN50155 for on‑board electronic equipment, EN45545 HL3 fire protection standard for rail vehicles and relevant TB/T standards for rolling stock. They have passed a complete set of type tests including high‑low temperature cycling, vibration fatigue, salt spray, short‑time short‑circuit current withstand and dielectric withstand voltage. We flexibly adjust the cross‑section, length, bending structure and plating scheme according to different customer requirements. Tinned products with large cross sections are preferred for main circuits of braking resistors to balance current carrying and corrosion resistance; silver‑plated options are available for critical high‑voltage grounding points to further stabilize contact resistance.
Xi’an Zipeng Technology provides one‑stop customized services for main engine manufacturers and converter supporting enterprises, ranging from drawing communication and sample trial production to bulk delivery. With in‑depth research on working conditions of EMU high‑voltage systems, we keep optimizing the structure and technology of copper flexible busbars. By delivering stable and reliable flexible conductive products, we consolidate the safety barrier for braking energy dissipation and high‑voltage grounding of EMUs, and support the high‑quality localization development of rail transit equipment.
Need a sample for testing? welcome to mail: info@zpbusbar.com
About US
At Zipeng, we specialize in the engineering and manufacturing of custom Copper Foil Flexible Busbars, and Copper Laminated Flexible Busbars for high-current electrical applications. Our products are designed to deliver reliable conductivity, long service life, and stable performance in demanding industries including battery energy storage, power distribution, switchgear, transformers, renewable energy, and industrial automation.
Media Contact
Company Name: Xi’an Zipeng Machinery Technology Co., Ltd
Contact Person: Media Relations
Email: Send Email
Country: China
Website: https://www.zpbusbar.com/
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