SYMBOLIC EXPRESSIONS AND METHODS 89 



the symbolic expression for the currents in each circuit and the 

 total current; also the absolute values and tangents of angle of 

 lag. Check graphically. (10 min.) 



11. Two parallel circuits have resistances of 1 and 5 ohms and 

 reactances of 7 and 5 ohms; by the symbolic method find the 

 impressed e.m.f. with a total current of 100 amperes; check 

 graphically. (6 min.) 



12. Solve problem 29, Chapter V, by the symbolic method. 

 (5 min.) 



13. Solve problem 41, Chapter V, by the symbolic method. 

 (15 min.) 



14. Solve problem 44, Chapter V, by the symbolic method. 

 (12 min.) 



15. Solve problem 4, Chapter VI, by the symbolic method. 

 (5 min.) 



16. Solve problem 10, Chapter VI, by the symbolic method. 

 (8 min.) 



17. A 500-kv-a., 2000-volt single-phase transmission line has a 

 resistance of 0.22 and an inductive reactance of 0.36 ohm. What 

 e.m.f. must be generated to give 2000 volts with a unity power- 

 factor load? (4 min.) 



18. Repeat problem 17, with the power factor 70.7%. (5 min.) 



19. The no-load or exciting current of a 6000 to 2200, 100-kv-a. 

 transformer is 0.47 ampere, the iron loss is 1020 watts. By 

 the symbolic method determine the total primary current for 

 full-load secondary current at unity power factor (referred to 

 secondary induced e.m.f.); also find the magnetizing component. 

 (5 min.) 



20. Same as problem 16, except that the load current has a 

 power factor of 70.7% referred to the induced e.m.f. (4 min.) 



21. A 20-kv-a., 3000 to 220-volt transformer has a secondary 

 resistance of 0.0126 ohm and a secondary reactance of 0.0110 

 ohm. With a secondary induced e.m.f. of 220 volts find the 

 terminal e.m.f. (symbolic expression) for a load of incandescent 

 lamps, having a resistance of 2.4 ohms. (25 min.) 



22. Repeat with a full-load current lagging 30 degrees behind 

 the induced e.m.f. (15 min.) 



23. The primary resistance being 2.25 ohms and the primary 

 reactance 1.96 ohms, find the primary e.m.f. and hence the regula- 

 tion in problem 21. Neglect the exciting current. (20 min.) 



