CHAPTER X 



80. Regulation of alternators and transformers 81. Behn-Eschenburg and Kapp's 

 method 82. Kapp's diagram 83. Algebraical method of determining drop 

 84. Rothert's ampere-turn method 85. Analysis of armature self-induct- 

 ance into two components 88. Experimental determination of two components 

 of armature reactance 87. Potier's method of predetermining the regulation 

 of an alternator. 



80. Regulation of Alternators and 

 Transformers 



ONE of the most important problems connected -with the behaviour 

 of an alternator or transformer is that of regulation. By this is meant 

 the ability of the apparatus to maintain a more or less constant 

 terminal p.d. with varying load. In the case of an alternator, the 

 exciting current is supposed to be constant ; in that of a transformer, 

 the primary p.d. is supposed constant. The regulation is frequently 

 expressed in terms of the percentage drop of voltage from no load to 

 full load. This drop depends very largely, as we shall see, on the 

 nature of the load, i.e. on its power factor. 



The regulation of either an alternator or transformer may be 

 determined by direct experiment if a suitable load and a sufficient 

 amount of power be available for carrying out the test. In many 

 cases, however, the power available is insufficient. Some indirect 

 mode of arriving at the regulation thus becomes desirable. Again, 

 the indirect method of determining the regulation leads to much more 

 accurate results in the case of transformers than could be obtained, 

 under ordinary testing conditions, by a direct test. Numerous attempts 

 have been made to devise such indirect methods in connection with 

 alternators, which present much more difficulty than transformers. 



81. Behn-Eschenburg and Kapp's Method 



The earliest of these methods is one which is equally applicable 

 to alternators and transformers. Its application to alternators we 

 owe to Behn-Eschenburg,* while Kapp f devised a similar method for 



* The Electrician, vol. xxxv. p. 424 (1895). 



t Elektrotechniache Zeittchrift, vol. xvi. p. 260 (1895). 



