&0Ma' / 



Figure 90. — Two views of Siemens' self-excited 

 alternator of 1882. From J. Dredge, Electric 

 illumination, London, n.d. (about 1882), vol. 

 I, figs. 274, 275. 



At first the Alliance machine was used to supply the 

 power, and this allowed the now rather moribund 

 Societe I'Alliance to continue its existence. However, 

 it was soon found that the Gramme generators were 

 more efficient."' In addition, with his usual in- 

 genuity, in 1878 Gramme devised alternating current 

 generators for 4, 16, and later 32 "candles" (fig. 86).""' 

 One type d'atelier dynamo was used to provide the 

 current for the electromagnet field coils of one or 

 more alternators. These last had a rotating field, 

 with 8 radial poles, and a stationary armature. 

 The coils were grouped on the stator so that a number 

 of circuits (normally with four "candles" per circuit) 

 could be taken off a single alternator. Each "candle" 

 provided about 100 Carcel units, and, as the following 

 tabulation shows, each consumed about 1 hp.: 



Cost 



Candles 



Length/width/ 

 height {cm.) 



Weight 

 (kg.) 



R.p.m. 



Hp. 



(£) 



(francs) 



16 



89 X 86 X 78 



650 



600 



16 



400 



10. 000 



6 



70 X 40 X 52 



280 



700 



6 



200 



5,000 



4 



55 X 40 X 48 



190 



800 



4 



100 



2,500 



i« Les Mondes, 1877, vol. 42, pp. 346-347; vol. 43, p. 779. 



11* French patent 120649 (October 23, 1877; additions, 

 December 3, 1877, and September 1, 1879); British patent 

 953 (March 9, 1878); Revue industrielle, 1878, vol. 7, pp. 222- 

 224; Engineering, 1878, vol. 26, pp. 63-66; 1881, vol. 32, pp. 

 251-253, 275-277, 299-302, 326-329, 353-355; Fontaine, 

 op. cit. (footnote 19), pp. 161-166. 



Two years later, in 1880, Gramme devised his 

 machine auto-excitatrice, which combined both the 

 alternator of 1878 and a 4-pole dynamo within a 

 single frame (figs. 87, 88)."-' Two sizes were manu- 

 factured — a small model weighing 280 kg. and re- 

 quiring 4 hp. to supply 12 "candles," and a large 

 one weighing 470 kg. and requiring 8 hp. to supply 

 24 "candles." The light from each "candle" was 

 from 20 to 30 Carcel units. Apparently this machine 

 auto-excitatrice was not patented. 



The Siemens dynamos also were used in the Jabloch- 

 koff system to e.xcite the Gramme alternator. How- 

 ever, it was not long before the Siemens firm had 

 designed its own alternator (fig. 89) and had a Paris 

 agent who supplied it in quantity. The construction 

 of the Siemens alternator was essentially that of the 

 VVoolrich machine, with electromagnets substituted 

 for the permanent magnets and with a disk armature 

 rotating between two stationary rings of electromag- 

 nets."" Depending on the size of the machine, there 



^^' Revue industrielle, 1880, vol. 9, pp. 53, 56-57: La Lumtere 

 Uectrique, 1880, vol. 2, pp. 88-89; Engineering, 1880, vol. 29, 

 p. 136. 



"6 German patents 2245 (March 9, 1878) and 3383 (April 3, 

 1878); French patents 123307 (March 20, 1878) and 12479 

 (May 27, 1878); British patent 3134 (August 8, 1878); La 

 Lumihre electriquc, 1879, vol. 1, pp. 25-26; Engineering, 1879, 

 vol. 27, pp. 181-182. 



PAPER 30: DEVELOPMENT OF ELECTRICAL TECHNOLOGY IN THE 19TH CENTURY: III 



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