The Elements of Steam Engineering Prepared for Students of the International Correspondence Schools, Scranton, Pa Volume 2 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1897 edition. Excerpt: ...coil in the same direction as represented in Fig. 866. The current, circulating around the armature coil in two directions, acts as a magnetizing force upon the core and produces two electro-magnets. According to the rule for magnetic polarity, the two magnets thus formed oppose each other at the two neutral spaces of the armature; that is, their like poles./V, N' and S, S' tend to act in opposite directions at the neutral spaces. As previously explained, lines of force can never intersect each other, and will always produce consequent poles when acting in opposite directions at one place. Therefore, in this case, two consequent poles are formed in the. core, one at each neutral space, as shown in the diagram. The polarity of the consequent poles, of course, depends upon the direction in which the coil is wound upon the core and the direction in which the current is generated. The same action occurs when the armature is rotated between the poles of a magnet and a current flows through the coil, although the conditions are somewhat altered. The lines of force from the magnet tend to pass through the core nearly at right angles to those produced by the current. The lines can never intersect, however, and they ' crowd and distort one another in order to coincide in direction. The lines that pass out from the north pole of the magnet tend to enter the core at the south consequent pole and to pass out from the core at the north consequent pole. At the same time, the southconsequent pole is shifted towards the north pole of the magnet, and the north consequent pole towards the south pole of the magnet. The diagram in Fig. 873 represents the manner in which the magnetic 'field is distorted by the reaction of the armature current. In...