Subtitle: ABB’s Customized SafePlus Series Solution Tackles Corrosion and Humidity Challenges for Undersea Infrastructure
When vehicles pass smoothly through the Mawan Undersea Tunnel in Shenzhen, few people realize that this 8.05-kilometer-long “undersea passage” is facing the dual environmental challenges of high corrosion under the sea and high humidity inside. As Shenzhen’s first cross-sea tunnel, the Mawan Undersea Tunnel was officially opened to traffic on January 21, 2025. The maximum excavation diameter of its two undersea shield tunnels reaches 15.5 meters, setting a new record for the diameter of undersea shield tunnels in China. The 1.1-kilometer underwater section has further increased the difficulty of power support for this important transportation artery.
In the undersea environment, high-concentration chloride ions will cause continuous corrosion to metal equipment. Due to poor air circulation inside the tunnel, a humid and hot state is maintained for a long time, and water vapor is easy to condense on the surface of the equipment, which may lead to short circuits, faults, and other problems. For the tunnel, electricity is not only the “energy source” for lighting and ventilation but also the “lifeline” for emergency rescue and fire-fighting systems. Once the power supply is interrupted, the tunnel may be plunged into darkness, the shutdown of the ventilation system will cause the accumulation of harmful gases, and the inability to start the fire-fighting equipment will greatly increase the safety risk. Therefore, equipping the Mawan Undersea Tunnel with a power distribution system that can resist harsh environments and ensure continuous power supply has become a key issue in the project construction process.
Against this background, relying on its profound technical accumulation in the electrical field, ABB has carried out in-depth cooperation with Shenzhen Auster Electric Technology Co., Ltd. to customize a power distribution solution centered on the SafePlus series ring main units for the tunnel. This solution is not a simple application of general-purpose products but has undergone multi-dimensional special optimization for the special environment and power supply needs of the Mawan Undersea Tunnel, overcoming undersea power distribution challenges in all aspects from design to performance.
From the perspective of power supply reliability design, the ABB team fully considered the tunnel’s demand for “zero power outage” and deeply integrated the solution with the dual-ring network design of the design institute. Each power distribution room is equipped with two independent power sources. This dual-power backup mode completely eliminates the risk of power supply interruption caused by a single power source failure. At the same time, in view of the limited space of the power distribution room in the tunnel, the solution has carried out refined planning on the equipment installation layout to achieve the optimal power supply layout in the limited space, which not only ensures the normal operation of the equipment but also reserves space for the installation of other facilities in the tunnel.
The “hardcore” product performance is the core support for the solution to resist harsh environments. The ABB SafePlus series ring main units adopt a fully insulated and fully sealed structure. Their gas tanks are welded by fully automatic robots, and the sealing performance meets high industry standards, which can completely isolate all live parts from the external humid and corrosive environment. To further improve safety, the equipment is also equipped with a mechanical interlocking device, which can force the standardization of the operation sequence and avoid safety accidents caused by misoperation; the design of pressure relief holes and pressure relief channels can quickly release pressure when the internal pressure of the gas tank is abnormal, ensuring the personal safety of operation and maintenance personnel.
The modular design is a major innovative highlight of the SafePlus series ring main units. The equipment adopts a structure of 6 units sharing a gas chamber, which means that even if the gas chamber of a certain unit fails, only that unit needs to be taken out of operation, and the other 5 units can still supply power normally. This greatly shortens the fault handling time and reduces the impact range of power supply interruption. The German imported vacuum interrupter used in the circuit breaker is a “key component” for the high performance of the equipment – its vacuum degree is lower than 10⁻⁸ mbar, and combined with high-purity copper-chromium alloy material and rotating contact design, it can achieve strong breaking capacity. Even in the face of sudden current impact, it can stably cut off the circuit and ensure system safety.
In addition, the IP67 protection level of the SafePlus series ring main units allows them to be immersed in water 1 meter deep for 30 minutes without affecting normal operation. This performance is perfectly suitable for the humid environment in the tunnel where water accumulation may occur; the compact size design effectively reduces the space occupied by the equipment in the power distribution room, providing the possibility for the efficient use of space in the tunnel.
“Cooperation with ABB has allowed us to see the strong advantages of customized power distribution solutions,” said Li Haiqun, General Manager of Shenzhen Auster Electric Technology Co., Ltd. He stated that the modular design and intelligent configuration system of the ABB SafePlus series ring main units can achieve full-scenario adaptation from voltage level to capacity range. The team can quickly adjust the solution according to the actual needs of the tunnel, and the entire process from design to delivery has achieved efficient response, providing important support for the project to be completed on schedule.
Luo Hui, Head of ABB Electrification China’s Power Distribution Systems Business Unit, pointed out that the Mawan Undersea Tunnel project is a typical case of the combination of ABB’s technical strength and the channel capabilities of partners. “We have always believed that technological innovation needs to be closely integrated with market demand. Through cooperation with Auster Electric, we have applied advanced power distribution technology to the construction of key infrastructure, which not only improves the power reliability of the tunnel but also provides a reference for the upgrade of the power distribution system of urban transportation infrastructure,” Luo Hui said. He added that in the future, ABB will continue to deepen its presence in the smart grid field, make continuous efforts in urban power grid upgrading and new energy infrastructure, and work with partners to build a safe, intelligent, and efficient power distribution ecosystem, contributing more “ABB solutions” to China’s infrastructure construction.
Looking back, the major transportation infrastructure projects that ABB has participated in in China have already formed a “matrix” – the presence of ABB’s power distribution equipment can be seen in landmark projects such as the Hong Kong-Zhuhai-Macao Bridge, the tunnel of Shanghai Hongqiao Hub, and the Qinling Zhongnanshan Tunnel. As a global electrical giant with a history of more than 140 years, ABB has always taken technology as the core and win-win cooperation as the concept, continuously injecting power into the high-quality development of China’s transportation industry and guarding every “transportation lifeline” with reliable power distribution solutions.
Post time: Sep-01-2025