Analysis of transient electric field distribution inside the large generator under strong surge voltage

• A novel analysis method of transient electric field in large generators is presented.
• The calculation with high accuracy for the transient electric field can be obtained.
• The insulation fault points can be predicted successfully under strong surge voltage.
• It is very necessary to protect the winding insulation against the surge voltage.

In the large hydropower station, the large generators will be suffered from the electrical damage under the powerful surge voltage, and they may be easily also stricken by some surge voltage from the power transmission lines at any time, in which the hazard of transient over-voltage is more serious to the internal electrical insulation of the large generator. Therefore, it is very necessary to analyze the transient electric field distribution for protecting the electrical insulation inside the large generators. In the paper, the analysis of transient electric field distribution inside the large generator under strong surge voltage is presented, in which a field-circuit calculation method is approached, and the transient electric field distribution inside the large generator is fully analyzed by the hybrid analysis method.