r/AYT/7'N 125 



three-phase transmission line, which has a resistance of 2.38 ohms 

 and an inductance of 7.<> millihenrys per conductor. The full- 

 load capacity of the generating station is 320 amperes per lino. 

 A synchronous motor is to be added at the load both to compensate 

 for power factor and to supply additional power. Assume that 

 the efficiency of this synchronous motor and its exciter is 92 per 

 cent, at full load and with unit power factor. The voltage at 

 the load is maintained constant. The frequency is 60 cycles. 



( alculate the kilovolt-ampere capacity of the synchronous motor 

 so that the generating station can deliver its full-load current at 

 unit power factor. What additional power can the synchronous 

 motor supply? At what power factor does the synchronous 

 motor operate? What is the necessary line voltage at the 

 generating station before and after the synchronous motor 

 is added 1 / 



75. An induction motor load taking 26,000 kw. at 0.906 

 power factor and with a line voltage of 6600 volts is operated at 

 the end of a high-tension transmission line. At the end- of the lint- 

 there are step-up and step-down transformers, which have the 

 same ratio of transformation. The total equivalent resistance and 

 reactance of the line and transformers referred to the low-ten -i on 

 sides are 0.431 ohm and 0.986 ohm at 25 cycles respectively, 

 chronous motors, running light, but taking their full-load current . 

 are added at the load to improve the power factor and thus 

 increase the capacity of the generating station. Assume that the 

 full-load efficiency of the synchronous motors and their exciters 

 is 0.92 at unit power fa. -tor. The voltage at the load is main- 

 tained constant. Induction motors operating at the same power 

 factor a< do the others are added at the load and the .synchronous 

 motors are adjusted -o that the re-ultant power factor of t lie load 

 is increased to unity. 



For the same line current as required lieiWr the addition of 

 the synchronous motors calculate the permissible increase in the 

 induction motor load What i- the necessary Idlovolt-ampere 

 capacity of the synchronous motors? At what power factor was 

 the generating station and after the synchronous 



motors were added'.' What was the line voltage at the generating 

 station before and after the synchronous motors were added? 



