What tool is used to check a motor or generator armature for shorts and opens under load conditions?

The tool used to check a motor or generator armature for shorts and opens under load conditions is the growler. This device is specifically designed to test the armature windings by inducing a magnetic field. When the armature is placed on the growler, any shorted turns in the winding cause a loss of magnetic flux, which can be detected by a small metal tool or blade that is passed over the armature. If there are shorts, the blade will vibrate or move, indicating a problem.

Other tools, while useful for electrical testing, do not perform this specific function. A multimeter can measure resistance, voltage, and current but is not effective for diagnosing issues under load conditions in the same manner as a growler. An ohmmeter measures resistance directly, which can help in identifying open circuits but lacks the capability to test under load. A voltmeter is used to measure electrical potential difference but does not provide information regarding the continuity of windings or the operational integrity of the armature specifically. Thus, the growler is the most appropriate tool for this specific testing requirement.