Reliability and Redundancy
The Importance of Uninterrupted Power Supply
April 2026
A central aspect of redundancy on cable repair vessels is ensuring a stable power supply for propulsion systems and mission-critical onboard systems. Only in this way can the vessel maintain its position even under extreme sea conditions—a shipwide blackout is unacceptable.
C-Systems has implemented a closed busbar system on this cable repair vessel, rather than the conventional open system. But how does the company address the challenges of short-circuit protection, generator protection, and certification by classification societies?
Circuit Breakers Detect the Direction of Fault Currents
The first line of defense consists of circuit breakers that detect the direction of fault currents and selectively disconnect them. This principle, known as zone selectivity, allows short circuits to be isolated with precision.
“Short circuits require a response within 100 milliseconds,” emphasizes Jeroen. “Otherwise, cascading effects could lead to a total system failure.” C-Systems uses ABB circuit breakers to minimize risks and reduce development effort.
To validate the system, C-Systems conducted hardware-in-the-loop tests at ABB’s simulation laboratory in Bergamo. “The basic configuration of the electrical system has already been tested and approved. However, final verification will only take place during the vessel’s commissioning.”
Generator Protection: Preventing Overload and Malfunctions
In addition to short circuits, a closed busbar system must also safely manage generator failures. “Due to the redundancy groups, a maximum of one generator is allowed to fail,” explains Jeroen. “If a fault occurs, the affected generator must be isolated without compromising overall system stability.”
A critical component is the automatic voltage regulator (AVR) of the generators. While under-excitation (lack of excitation current) is relatively easy to detect, over-excitation (excessive voltage) poses a greater challenge. “How do you detect over-excitation—and how do you locate the faulty generator?”, asks Jeroen.
C-Systems’ solution: the Bachmann GSP274 system. Seventeen modules continuously monitor active and reactive power, excitation current, and generator speed. “This allows us to detect deviations in excitation current early and prevent malfunctions,” explains Jeroen. “The system gives us precious seconds—which, in control technology, is a decisive timeframe.”
Redundancy: Ensuring Continuity Even in Case of System Failures
On cable repair vessels, redundancy is indispensable. Essential components such as generators, propulsion systems, and switchgear are duplicated to ensure seamless takeover in the event of failures. The dynamic positioning system DP2 maintains the vessel’s position even if a generator or thruster fails.
“Redundancy ensures operational continuity, no matter what challenges the sea presents,” Jeroen concludes. “Our goal is for the vessel to perform its tasks safely and reliably.”
