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Reasons for Generating Shaft Current in Diesel Generator Sets

Oct. 24, 2023

When the reason for the shaft current generated by diesel generator sets is attributed to electromagnetic effects, it causes serious damage to diesel generator sets with longer operating cycles. The main manifestation is that the shaft current generates electric spark discharge in the radial bearings, thrust bearings, floating ring seals, couplings, and transmission gears of the diesel generator set, damaging the metal surface and damaging the oil film. If not discovered for a long time, it will cause serious damage to the mechanical components of the diesel generator set. Why does a diesel generator set generate shaft current? The reasons are as follows:


diesel engine


In the case of a diesel generator set with an electric motor rotor, the main reason is the asymmetric distribution of magnetic field lines and the magnetization effect of the rotor shaft, which generates shaft current. The asymmetric distribution of magnetic field lines is usually caused by the asymmetric gap of the laminated layer. Another phenomenon is the generation of shaft current due to the application of external potential. The reason is that the rotating magnetic field of a mobile generator cuts the conductor or the rotor is unbalanced, resulting in shaft magnetization. Friction, welding, collision, and eddy current devices may all cause the equipment to become magnetic and establish a magnetic field. When a rotating magnetic field cuts a conductor, it induces a certain potential within these parts. When the potential rises enough to break through the oil film, a current circuit is formed.


This current circuit may pass through the entire rotor, or it may only form local short circuit currents in the bearings or floating ring seals, which in turn generate new magnetic fields to magnetize the shaft or other parts. Therefore, this type of magneto electric conversion creates a strong magnetic field and high current in the diesel generator set. The voltage that causes the diesel generator set to generate shaft current is above 20V, and the damaged voltage is between 30-100V. Therefore, ensuring the normal operation of the diesel generator set can effectively limit the voltage of the diesel generator set. Once the voltage is below 1V, shaft current will definitely not be generated.


Guangxi Dingbo Power Equipment Manufacturing Co.,Ltd was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. The company has a registered capital of 218.88 million yuan. The company covers an area of 86,000 square meters and a building area of 55,000 square meters. There are more than 660 employees, including 456 professional technicians and 106 senior technicians. It has 46 sales and service outlets nationwide. The main products are diesel engines, generator sets, and diesel generators, providing users with a one-stop service of design, supply, debugging and maintenance at any time. Dingbo has always insisted on using first-class talents, building first-class enterprises, manufacturing first-class products, creating first-class services, and making every effort to build a first-class domestic enterprise. If any question please feel free to visit our website https://www.dieselgeneratortech.com/ or send email to sales@dieselgeneratortech.com.

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