PERFORMANCE INDEX OF QUARTZ PLATES 



247 



4 6 8 10 



20 



40 60 80 100 



Fig. 15.12 — Inherent error of the P.I. meter due to tuning for an indication of minimum 

 impedance rather than unity power factor. 



Rewriting (15.84) we have 



r [i - 4/1 - jsi 



Per cent Error of P.I. = 100 1 - ^ ' — tlj^ (15.86) 



[Z' + li-l 



If Co » C. then 



A = 



M 



,+g+M{ 



;) 



(15.87) 



The error given by (15.86) is plotted in Fig. 15.12 as a function of P^ 



