THE REGULATION OF TKANsFoliMKIlS 107 



tam-e drop 90,0 volts. In Fig. 60 (which is based on a 

 diagram devised 1>\ Kapp *) A D and D C are drawn to scale, 

 and art respectively proportional to 87, (> and '.(),(). With .-1 

 as a centre, and a radius proportional to 5000 (the constant 

 primary pressure), the arc BQ Bgo is drawn. Radiating from C 

 are drawn lines representing the phase of the secondary terminal 

 pressure lor various power factors. These lines intersect the 

 an B Bgo at various points, B 0t B Wt B&, etc., the subscripts 

 denoting the angle by which the vector C B , representing the 

 secondary current, lags behind the secondary terminal pressure. 

 The lengths of the lines C B , C B Wt C B&, etc., are propor- 

 tional io the secondary terminal pressure for the case of an 

 equivalent transformer witli a 1:1 ratio of transformation. The 

 actual secondary terminal pressures for these conditions of load, 

 and for the constant primary pressure of 5000 volts, may be 

 found ly dividing these results by 25, the ratio of transforma- 

 tion of the aetual transformer. It is seen from the diagram 

 that the regulation lies between 1,70 per cent, and 2,56 per 



. according to the power factor of the external circuit 



lied l>y the secondary. 



Kapp't Modified Diagram of />/<>;>. The graphical method 

 of estimating tin- regulation at various power factors, as shown 

 in I uffers from tin- disadvantage that in practice the 



distance representing the droj rally \ TV small in coin- 



-n with the radii of the circle, so that an accurate deter- 



i of the drop hy a purely graphical method becomes 



impracticable. If. however, .1 /> and /> < (] are v TV 



.1 compared with C BIQ, C J5 etc.. then Kapj.-' has sho\\n 

 it beeomei pra.-ti.-al.le to simplify the diagram, \\ithoiit 



II- Ura tb difficulty aboT6-mentioned< Tin- metliod 



will le exclaim d I-; nee to 1 and I'M. I f in 



6fi a line is dra\\n i..niiiiL f .1 and //,,,, then this will be 



, , - , 



