A Textbook On Electric Lighting And Railways Electric Railways Interior Wiring PDF Download

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. 1901 edition. Excerpt: ...fr, c, d, e, etc., are connected in series. The ends marked i are inside ends of coils; those marked o are outside ends. Outside of the change in the style of armature and some improvements in the bearings, the T. H. machine has been changed but little since it was first brought out. 19. General Remarks on T. II. Machines.--In operating the T. H. machine, care must be taken to see that the brushes are correctly set, with regard to the commutator, and also that the commutator is properly set on the shaft, with regard to the armature. Instructions for doing this are furnished by the manufacturers and a gauge is provided for setting the brushes. Failure to attend to these points will result in "flashing," or the machine may refuse to pick up its load at all. 30. Flashing is a fault to which arc-light dynamos are especially subject. It consists in a momentary short-circuiting of the machine by an arc jumping around the commutator from brush to brush. This produces a flash, so well known in connection with these machines. It may arise from a number of different causes. In the T. II. machine, an improper setting of the brushes or commutator referred to above may cause it, also defects in the air blast. If the jets become stopped up or if the blower itself is out of order, the puffs of air will not be delivered so as to blow out the spark. This will allow it to carry over to the adjacent segment and a flash will result. A flash is immediately followed by a lowering of the regulator and must not be confounded with the ordinary sparking of the machine. When a T. II. machine is running under normal conditions, there is a spark about-j to inch long at the ends of the brushes. This spark has a violet tinge and does no special harm; in fact, ...