An elementary book on electricity and magnetism and their applications . l voltage at all loads. But as more current is drawn fromthe machine the terminal voltage falls, until at point A thegenerator commences to break down. Any further at-tempts to increase the load result in an abrupt decrease of bothvoltage and current. Therefore OA is the operating portionof the curve. In large machines the break-down point ismany times their normal load. With a field rheostat to controlthe field current, a constant terminal voltage may be main-tained throughout the normal operating range of the machine. C
An elementary book on electricity and magnetism and their applications . l voltage at all loads. But as more current is drawn fromthe machine the terminal voltage falls, until at point A thegenerator commences to break down. Any further at-tempts to increase the load result in an abrupt decrease of bothvoltage and current. Therefore OA is the operating portionof the curve. In large machines the break-down point ismany times their normal load. With a field rheostat to controlthe field current, a constant terminal voltage may be main-tained throughout the normal operating range of the machine. Compound-wound generators have quite an advantage forfurnishing current to be used by electric motors, that is, forpower distribution, because they automatically keep the voltageconstant through the combined action of the shunt and seriesfield windings. The voltage supplied by shunt-wound gen-erators decreases to a certain degree as the current furnishedby the armature increases on account of the resistance of thearmature and because the magnetism set up by the current. Fig. 149 a. — Direct-current generator connected directly to a steam engine. DIRECT-CURRENT GENERATORS 215
Size: 1855px × 1347px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectmagnetism, bookyear19
