[Electric engineering.] . llel,and hence the series system was developed for this work. S 16 ELECTRIC LIGHTING. 61 When a number of lamps are connected in series in acircuit, the current in that circuit must be kept at thesame value, no matter how many lamps are in term constant current, as applied to this system,implies, therefore, that the current is maintained at aconstant value and not that the current is a direct orcontinuous one. As mentioned above, such circuits arerun from constant-potential alternators, a regulator beingused in each circuit to keep the current at a const
[Electric engineering.] . llel,and hence the series system was developed for this work. S 16 ELECTRIC LIGHTING. 61 When a number of lamps are connected in series in acircuit, the current in that circuit must be kept at thesame value, no matter how many lamps are in term constant current, as applied to this system,implies, therefore, that the current is maintained at aconstant value and not that the current is a direct orcontinuous one. As mentioned above, such circuits arerun from constant-potential alternators, a regulator beingused in each circuit to keep the current at a constantvalue. The . series-incandescent system of street lightingis especially useful for small plants, where it would notpay to install separate arc-light dynamos. The system isalso used in larger places on streets that are very heavilyshaded or in alleys or other places where an arc light ishardly necessary. 12. Fig. 36 shows a series of incandescent lamps /, / con-nected across an ordinary constant-potential circuit fed by. 3 Transformer FIG. 36. the alternator A. Suppose, for example, that the pressuregenerated by the dynamo is 1,000 volts; then if each lamprequired, say, 20 volts, 50 lamps would have to be run in 62 ELECTRIC LIGHTING. § 16 series in order to take up the full voltage of the for use on circuits of this kind are often made for acurrent of 34- amperes and a pressure of 20 volts. Suchlamps have short, thick filaments, and are generally of theshape shown in Fig. 4. Unfortunately, lamps with short,thick filaments are not nearly as efficient as the ordinary50-volt or 110-volt lamp with a long, thin filament. Forthis reason, some of the more recent systems of series-incan-descent lighting employ circuits using 50-volt or 100-voltlamps, and use a correspondingly smaller number on eachcircuit. This is, the case with the Westinghouse seriessystem to be described later. So long as none of the lampsburn out, the current in the circuit will remain constant,beca
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