An easy and most general method to test armature winding for short and open coils is through a growler.
There are two types of growlers. They are as follow:
1) Internal growlers
2) External growlers.
An external growler is employed for testing small armatures while the internal growler for large DC armatures and AC motor stator windings.
Internal Growler:
An internal growler, like the one employed for stators, may be employed for armatures as well. Internal growlers are made with or without built-in feelers.
The growler that is with a built-in feeler has a flexible blade attached to the growler that is why a hacksaw blade or identical instrument is not essential.
This type is particularly wanted in smaller stators that contain no room for a separate feeler. The below diagram depicts an internal growler with a separate feeler, employed for large armatures.
