What type of test checks motor insulation over the life of the motor?

The type of test that checks motor insulation over the life of the motor is the insulation spot test. This method involves measuring the insulation resistance at specific points in time or under certain conditions, enabling technicians to monitor the health of the motor's insulation throughout its operational life. By conducting this test periodically, any degradation in the insulation can be detected early, potentially preventing failures and extending the lifespan of the motor.

This approach is crucial as the insulation system is vital for safe motor operation, protecting against electrical faults and ensuring efficiency. The insulation spot test provides a snapshot of the insulation condition, helping to identify any anomalies or areas that require maintenance before they lead to more significant issues.

Other testing methods mentioned have different purposes. For instance, a continuous test monitors insulation resistance in real-time, and a voltage test generally assesses operational voltage levels, which are not specific to insulation longevity. Meanwhile, a short-circuit test evaluates the system's response to short circuits and does not focus on insulation integrity. Hence, the insulation spot test is the most relevant for assessing insulation over the motor's lifetime.