Which test will indicate the serviceability of a medium-voltage vacuum interrupter?

The correct choice is the Vacuum Bottle Integrity Test, which is specifically designed to assess the condition and performance of vacuum interrupters in medium-voltage switchgear. Over time, vacuum interrupters can develop issues such as deterioration of the vacuum envelope or internal wear, which can lead to failure in service.

The integrity of the vacuum within the device is crucial for its operation because the vacuum is what allows the interrupter to effectively extinguish the arc when switching. During the Vacuum Bottle Integrity Test, the device is evaluated to ensure that the vacuum level is sufficient and that the interrupting mechanism is functioning properly. A failure in this test would indicate that the vacuum interrupter may not perform reliably under load conditions.

Other tests, such as the Insulation Resistance Test, Insulation Power Factor, and Partial Discharge Testing, while important for assessing the overall health of electrical systems and components, do not specifically focus on the performance of vacuum interrupters. For instance, insulation resistance tests measure the effectiveness of insulation but do not provide direct information about the condition of the vacuum or mechanical aspects of the interrupter. Therefore, the Vacuum Bottle Integrity Test is the most appropriate choice for determining the serviceability of a medium-voltage vacuum interrupter.