164 



TRANSFORMERS. 



[Exp. 



These are equivalent or apparent values, in terms of the primary, 

 and include the effect of both primary and secondary. The 

 effect of load losses is included in the values of W c and R. 



10 



0.25 



0.5 0.75 



AMPERES, PRIMARY 



1.05 



FIG. 7. Short-circuit test, 2 K.W. transformer, 2,ooo-volt coil. Voltage drop 

 due to impedance resistance and leakage reactance. 



26. Compare this value of R with the value found from 

 resistance measurements of R^ and R 2 in 16. 



27. Where tests are made at different frequencies, compute 

 the mean value of X-~-n for each frequency; the value should 

 be about the same for all frequencies. 



28. The values of X affect regulation but not efficiency; 

 while the values of R affect not only regulation (on account of 

 RI drop) but also efficiency (on account of RI 2 loss). 



29. Curves for Voltage Drop. Using the values of Z, R 

 and X thus determined (25), plot curves for ZI lt 7?/ t and XI \ 

 drops for different values of primary current, as in Fig. 7, these 

 curves being straight lines. Compare these curves with the cor- 

 responding curves for an alternator, Fig. 2, Exp. 3~B. 



For normal full-load current, mark the value of each drop 

 in volts and as per cent, of normal full-load voltage. The per 



