What is the correct method to test generator or motor armature windings for opens?

The method of placing the armature in a growler and connecting a 110V test light on adjacent segments is an effective way to test generator or motor armature windings for opens. A growler operates by creating a magnetic field that induces a current in the windings. When the test light is connected to two adjacent segments of the commutator, if there are no opens in the windings, the induced current will complete the circuit, and the test light will illuminate, indicating continuity.

This method is advantageous because it provides a clear visual indication of the condition of the armature windings and can help identify specific areas where breaks or opens may occur. It allows for the testing of the entire winding at once rather than isolating one segment at a time.

In contrast, using a voltmeter to measure voltage across the terminals may not reveal winding opens, as the voltage can still be present even if an open circuit exists, leading to potential misdiagnoses. Checking adjacent segments with an ohmmeter might not provide sufficient detail, particularly if the winding opens are intermittent or happen under load. Utilizing a test light between the armature core segments and the shaft is not a reliable method either; this could potentially damage the armature or give misleading