In recent years, a number of projects under construction in nuclear power plants have successively experienced excitator failures at key nodes of grid connection and commercial transportation, resulting in downtime, which has had a great impact on the progress and operation performance of the unit. The rotary rectifier bridge is an important part of the generator excitation system and is the most important link in the final realization of the rotor excitation. As a rotary rectifier equipment, it is difficult to achieve online real-time monitoring, the current large-scale nuclear power unit rotary rectifier bridge online real-time monitoring results are not ideal, there is on-site feedback false alarm, the need for high maintenance costs. With the gradual increase of nuclear power units, it is particularly important to develop a real-time online monitoring device for brushless rotary rectifier bridges and to achieve early warning. The equipment can win valuable time for the operation and maintenance of the unit, even if it needs to be protected indirectly by other protections in the event of failure, it can also provide direct data for post-accident problem analysis, locate the fault point, reduce the problem analysis time, improve the maintenance efficiency, and have great economic benefits.