Power-Factor Fluctuation of Directly Water-Cooled Generator-Bar after Water-Penetration inside the Groundwall Insulation

A directly water-cooled generator-bar with laboratory tests is presented in this paper. A leak point is made inside the groundwall insulation of the bar. The cooling water migrates along the generator bar through insulation delamination and interstices between copper strands. The speed of water flow inside the insulation is measured during the test period. Capacitance and power-factor mapping tests are carried out along the generator-bar length. The results show that the capacitance and dissipation factor are fluctuated reversely over a period of time. Dissipation factor variation of the generator-bar is higher than the capacitance variation.