Motor armature testing – or – what is a growler?
A common fault that cannot always be reliably identified with a simple ohmmeter test is a couple of shorted turns in the winding that do not affect the total resistance significantly. A growler is basically an AC electromagnet exciting the windings in the armature. A shorted armature winding will act as a the secondary of a transformer resulting in a high current flow and high induced magnetic field. Hold a piece of spring steel like a hacksaw blade as a probe over the armature as you rotate it slowly on the electromagnet. A shorted winding will show up as a strong audible vibration of the ‘probe’ – thus the name growler. Small motor repair and replacement (From: mjsrnec (mjsrnec@prairie.lakes.com).) Most motor shops won’t bother with the universal motors because they are much cheaper to replace than repair. However, if yours is a special be prepared to pay standard rates for the service. Email the Electrical Apparatus Service Association to find the EASA shop nearest you. If you think
