TRANSFORMERS 5 



netic circuit the current becomes 100 amperes. By what amount 

 are the apparent resistance and reactance of the reactor changed 

 by the introduction of the air-gap? 



20. A reactor with a laminated magnetic circuit has a resistance 

 to direct current of 0.5 ohm. When 110 volts at 60 cycles is 

 impressed on this reactor the apparent resistance and reactance 

 are 2 . ohms and 4.0 ohms respectively. What is the actual in- 

 ductance of the reactor at this voltage? 



21. At no load with 220 volts at 60 cycles impressed on a 

 transformer the ratio of eddy current loss to hysteresis loss is 

 1:3. What is this ratio if 220 volts at 50 cycles is impressed on 

 the transformer? 



22. At no load with 220 volts at 60 cycles impressed on a 

 transformer the ratio of eddy current loss to hysteresis loss is 1 :3. 

 What is this ratio if 110 volts at 60 cycles is impressed on the 

 transformer? 



23. At no load with 110 volts at 60 cycles impressed on a trans- 

 former the current is 1.3 amperes and the power is 52 watts. 

 What will be the no-load current and power taken by a trans- 

 former similar to this in every particular, except that the cross- 

 section of the magnetic circuit is double, when 220 volts at 60 

 cycles is impressed on it? 



24. At no load with 110 volts at 30 cycles impressed on a trans- 

 former the current is 1.2 amperes and the power is 53 watts, of 

 which 14 watts is dissipated in eddy currents. What will be the 

 in rent and power at no load if 220 volts at 60 cycles is impressed 

 on thi< trail-former'.' 



25. The hitfh-tensioii winding of a transformer consists of two 

 coils which may be connected in series or in parallel. When 



oils are connected in series across 2200 volts at 60 cycles 

 the current is 0.30 amperes and the power is 140 watts on oprn 

 circuit. What is the no-load current and power if the coils are 

 connected in parallel across 1100 volts at 60 cycles? 



26.' In problem 2.") what is the no-load current and pown- when 

 oils are connected in parallel across 1 />.">() volts at 60 cycles? 



1 Assume that tin- orium.-il flux <\, > kil..lm.- p,-r -,, in., and that 



tin- n lit ion between the flux density ami tin- prnnralulily for tin's quality 

 ssed by: 



B-102-0.017 



<-quals 45 kiiolincs and B equals 9"> killm< s prr sq. in. In prob- 

 h<r< this applies the effect of the joints in the magm-tir rmuit \\ill 

 IH neglected. 



