Factory measurement system for sub Pico Coulomb partial discharge signal

For the evaluation of insulation condition, it has been found that the higher sensitivity of partial discharge measurement must be achieved during the factory test. Generally, partial discharge measurement of less than few Pico Coulombs can be performed in a shield room. However, it is not an economical solution for manufacturers to provide the shield room at their own factories due to the high installation cost and the space allocation. In the paper, the economical system for partial discharge measurement of sub Pico Coulomb level will be explained in detail.