2025年9月3日 BY
IN Corporate News
Mawan Undersea Tunnel: A New Milestone in the Guangdong-Hong Kong-Macao Greater Bay Area
On January 21, 2025, Shenzhen, a core city in the Guangdong-Hong Kong-Macao Greater Bay Area, reached a major milestone in transportation construction – the Mawan Undersea Tunnel, China’s largest-diameter undersea shield tunnel, was officially opened to traffic.


Stretching approximately 8.05 kilometers, this transportation artery starts at Yueliangwan Avenue, crosses Qianhai Bay northward, and ends at Xixiang Avenue. It consists of two undersea shield tunnels with a maximum excavation diameter of 15.5 meters, including a 1.1-kilometer underwater section, making it Shenzhen’s first truly cross-sea tunnel.


Its opening not only breaks down transportation barriers between Qianhai and Xixiang in western Shenzhen but also holds strategic significance for the interconnection of road networks in the Greater Bay Area.
Critical Demand: Uninterrupted Power for Tunnel Operation
However, the stable operation of this “undersea giant” relies heavily on reliable power support. The seabed stratum crossed by the tunnel has extremely high chloride ion content, resulting in much stronger corrosion than ordinary onshore environments.


Furthermore, the tunnel interior remains humid and hot for long periods. The combination of moisture and corrosive substances in the air places extremely strict requirements on the protection performance of power distribution equipment.


More importantly, as a key urban transportation infrastructure, critical loads in the tunnel – such as emergency lighting, ventilation systems, and fire-fighting equipment – must be supplied with “uninterrupted power”. If a power failure occurs, it will not only cause traffic paralysis but also potentially lead to safety accidents.
ABB’s Tailored Solution: Addressing Complex Challenges
To tackle these complex challenges, ABB, a global leader in electrical and automation technologies, partnered with Shenzhen Auster Electric Technology Co., Ltd. to develop a customized power distribution system solution for the Mawan Undersea Tunnel, with the SafePlus series ring main units (RMUs) at its core.


This solution is not a simple assembly of equipment. Instead, it is the result of in-depth R&D and project-specific design based on the tunnel’s actual scenarios, aiming to align power distribution needs with the goal of continuous power supply.
Design Advantages: Dual Insurance for Uninterrupted Supply
From a design perspective, the solution accurately aligns with the dual-ring network design concept of the engineering institute, equipping each power distribution room with two independent power sources.


This “dual insurance” design ensures that if one power source fails, the other can be switched on immediately. This fundamentally prevents power outages caused by single-source failures.


Meanwhile, considering the limited space in the tunnel and the complex equipment installation environment, the solution also includes specialized optimizations for equipment layout and installation processes. The entire power distribution system acts like a “power armor” tailored for the tunnel – it does not occupy excessive space while maximizing protection efficiency.
Product Performance: Hardcore Strength Against Harsh Environments
In terms of product performance, ABB’s SafePlus series RMUs demonstrate exceptional “hardcore strength”. These units feature a fully insulated and fully sealed structure, with all live parts enclosed in a gas tank welded by automatic robots.


This design fundamentally isolates humid air and corrosive substances from eroding internal components. Additionally, the equipment is equipped with reliable mechanical interlocks, which strictly regulate on-site operation sequences and prevent failures caused by human error.


Special pressure relief holes and channels are also installed, adding an extra “protective shield” for the safety of operating personnel.
Modular Design: Minimizing Fault Impact
Modular design is another key highlight of the SafePlus series RMUs. They adopt a structure with six units sharing one gas compartment. Even if a single compartment fails, only that compartment needs to be taken out of service, while others can resume power supply in a short time.


This significantly reduces the scope of fault impact and shortens recovery time. The circuit breakers in the units use imported German vacuum interrupters, with a vacuum degree of below 10⁻⁸ mbar.


Combined with high-purity copper-chromium alloy and rotating contact design, this ensures strong breaking capacity, perfectly meeting the tunnel’s demand for high reliability of power distribution equipment.


Moreover, the gas tank’s IP67 protection rating and compact size design not only enable stable operation in the tunnel’s harsh environment but also effectively reduce space occupation costs, leaving more room for the layout of other tunnel facilities.
Partner Perspective: Agile Response from Customization to Delivery
“The ABB SafePlus series RMU solution and the tunnel project-specific plan, with their modular design and intelligent configuration system, can achieve full-scenario adaptation from voltage levels to capacity ranges,” said Li Haiqun, General Manager of Shenzhen Auster Electric Technology Co., Ltd., when talking about the cooperation.


He added that this customization capability allows the team to quickly and accurately meet the needs of power grid users, realizing agile response from design to delivery and providing strong support for the smooth progress of the project.
“Sales Manager : Jinny
Email : sales1@xrjdcs.com
Whatsapp/Mobile:+86 15359273791″