JQR 251.36,37,41 Growlers and Tester, Bar to Bar, Armature Page 2

JQR 251.36, .37, .41

Previous Page	Identification and Testing of DC Armatures (Continued) Armature winding terminology, definitions, and amplifying information (continued) Plex Definition: The number of separate circuits required to complete the total armature circuit Amplifying information: The winding may consist of a single circuit. The winding may also consist of two or more circuits connected in parallel. A plex denotes the method of connecting the leads of an armature coil to the commutator (such as simplex-adjacent bars or duplex-alternate bars). Reentrancy Definition: The number of times a complete armature winding reenters or closes on itself Amplifying information: The winding may close only once (single reentrant) (see figure illustrating typical duplex single-reentrant lap-wound dc armature). The winding may close two or more times (double or triple reentrant) (see figure illustrating typical duplex double-reentrant lap-wound dc armature).
	Pole pitch Definition: The distance from the center of a main pole of one polarity to the center of the next main pole of opposite polarity Pole pitch is used in reference to wave windings almost exclusively because individual coil ends in wave windings are always connected to commutator bars that are about two pole pitches apart.	Click on image to enlarge. Pole Pitch
	Identifying windings as lap or wave Refer to equipment drawings in the manufacturer's technical manual. These drawings will normally depict the armature with a representative connected winding along with the total number of commutator bars and the bars to which the individual coils are connected. Also included will be information and drawings pertaining to the number of poles for which the motor or generator is designed. The following information can be either obtained from the manufacturer's technical manual or by looking at the actual motor or generator. If you cannot identify the type of winding from the representative drawing, use the following procedure. • Determine the total number of commutator bars. • Determine the number of poles for which the machine is designed. • Apply the following rules to the information you have obtained. •• If the machine is designed for four or eight poles and the armature has an even number of bars, then the armature will be lap wound. •• If the machine is designed for four or eight poles and the armature has an odd number of bars, then the armature will be wave wound. •• If the machine is designed for six poles and the armature has a number of bars that can be evenly divided by three (75, 90, etc.), then the armature will be lap wound. •• If the machine is designed for six poles and the armature has a number of bars that CANNOT be evenly divided by three (85, 95, etc.), then the armature will be wave wound.
	Meter methods of identifying winding type