Existing mechanical HVDC breakers are capable of interrupting high-voltage direct currents within several tens of milliseconds, but this is too slow to fulfill the requirements of a reliable HVDC grid. HVDC breakers based on semiconductors can easily overcome the limitations of operating speed, but generate large transfer losses, typically in the range of 30 percent of the losses of a voltage source converter station. To overcome these obstacles, Hitachi Energy has developed a hybrid HVDC breaker. The hybrid design has negligible conduction losses, while preserving ultra-fast current interruption capability. Within this lecture, we will present an operation principle of the hybrid HVDC breaker, its design principles and test program. The Hybrid HVDC breaker is an innovative product that combines the low losses of a mechanical switch with the superior current interrupting capabilities of a power electronic switch and fulfills the requirements of fast interruption of short-​circuit currents in HVDC grids. Until recently, no DC breaker has proven suitable for HVDC due to HVDC’s high voltage, high and fast-​rising short-​circuit current, and requirement for fast current interruption. This was our motivation to develop a new type of breaker – The Hybrid HVDC breaker. --- PDH credits will be provided to registered participants who make a special request during registration. Virtual: https://events.vtools.ieee.org/m/380838