Field tests are conducted on electrical equipment after installation and during routine maintenance to assess its condition and safety. There are several types of field tests, including acceptance tests for new equipment, routine maintenance tests performed regularly, and special maintenance tests for known issues. The tests evaluate insulation integrity, device functionality, circuit performance over time, and other factors. Common testing methods involve applying voltage to insulation, analyzing insulating liquids, ensuring proper relay and breaker operation, measuring time-current curves, evaluating ground resistance, detecting fault gases, and using infrared scans. The results are used to determine corrective actions, benchmark equipment health, and verify design standards are met.