There are three reasons for the imbalance of the magnetic field of the Hydraulic Turbine Generator, which in turn produces the shaft voltage:
(1). Unbalanced magnetic circuits and asymmetrical air gaps due to manufacturing and installation processes are unavoidable factors.
(2). Axis voltage is generated when an asymmetrical short circuit occurs inside or outside the generator. This is because the short-circuited portion of the stator winding has an induced current that prevents the resultant magnetic flux from passing through the stator region where the winding is located; at this time, the un-short portion of the stator winding does not have this phenomenon, and this effect is asymmetric with the stator magnetic circuit. Equivalently, an alternating magnetic flux whose axial direction is dominant is generated. If the stator winding lead wires are located on both sides of the generator length direction, an asymmetric external short circuit may also generate the shaft voltage.
(3). The excitation circuit grounding or the rotor winding turn-to-turn short circuit also produces a strong axial unbalanced flux. When the shaft voltage reaches a certain value, a current is generated by forming a closed loop through the bearing and its base, etc. This current is called the shaft current.
When the shaft voltage reaches a certain value, a current is generated by forming a closed loop through the bearing and its base, etc. This current is called the shaft current.
We also have the Horizontal Shaft Francis Turbine Generator for you, contact us and you can find out more.