Once an electromagnet loses its magnetism, it will undoubtedly affect the operation. To prevent the demagnetization of electromagnets, it is essential to understand the causes of demagnetization. The reasons for the loss of magnetism in electromagnets include: issues with the rotor winding, problems with the exciter, false tripping of the active demagnetization switch, damage to certain components or circuit faults in the semiconductor excitation system, and human error, among others.

The damage caused by the demagnetization of an electromagnet primarily manifests in the harm to the generator itself and the power system!

Damage to the generator itself:

The generator's magnetic field failure intensified the leakage flux at the stator end, causing overheating of the components and the end core.

(2) After asynchronous operation, the generator's equivalent reactance decreased from to . Consequently, the added reactive power absorbed from the system caused the stator winding to overheat.

(3) The differential frequency current in the generator rotor winding causes rated losses within the winding, resulting in the winding heating up.

(4) For large direct-cooled steam turbine generators, the average asynchronous torque has a lower maximum value, and the inertia constant is relatively reduced. The rotor is significantly asymmetric in both longitudinal and transverse axes. Due to these factors, under heavy load, the torque and active power of the demagnetized generator will experience severe fluctuations. This impact is more severe for hydro generators.

Damage to the power system:

(1) After the generator lost magnetism, due to the fluctuation of active power and the decrease in system voltage, it may have caused the adjacent generators operating normally to lose synchronization with the system, resulting in system vibration.

(2) A generator's loss of magnetism results in a significant shortage of reactive power within the system. When the system's reactive power reserve is insufficient, it will lead to a decrease in voltage. In severe cases, it can cause the voltage to collapse and the system to split apart.

(3) A generator lost magnetic flux, resulting in a voltage drop. Under the active adjustment of excitation equipment by other generators in the system, their reactive power output will increase. This caused certain generators, transformers, and transmission lines to experience overcurrent. Backup maintenance may have been triggered by the overcurrent, expanding the scope of the issue.

Once an electromagnet loses its magnetism, it not only affects the operation but can also harm generators and the power system. Therefore, it's crucial to prevent demagnetization of electromagnets during daily use of machinery. I hope you now know how to prevent demagnetization after reading this article! I wish it brings you assistance!