Vacuum interrupter is an alternative device that contributes to reducing usage of SF6 gas insulated apparatus in the future. Since the application of vacuum technology is promising, the performance of VI should be retained for power system stability. For the past research we have investigated the partial discharge phenomena and determined the gas pressure in VI based on PD from the Paschen minimum up to the right side of few kPa order. It is also important to identify the PD phenomena and determine the gas pressure of VI based on PD at the left side of Paschen minimum for early detection purposes. Thus,this paper presents the construction of PD diagnostic study in VI. The constructed system is confirmed free from corona discharge and no PD occurs at pressure less than 0.4 Pa.