QUESTIONS AND mmu.KMS 503 



3. Why are 6,600-volt generators commonly used when the transmission 



mh? What rough basis can be used for determining tin- 

 mission voltage? What economic consideration.- arc involved in determining 

 this voltage? 



4. Give the principal links in a power system which distributes jx.-. 



and small consumers located at a considerable di> MI the 



|H)int of generation of power. State the considerations which govern tin- 

 selection of each of these links. 



5. Why are the voltages ordinarily selected for power and for lighting 

 purposes usually different? Why should the secondaries of lighting 

 formers be grounded ? 



6. Nam. the various types of apparatus which may be installed in a sub- 

 station, giving the tyjw of x rvi<-< which each supplies. 



7. Make a sketch of the magnetic field existing between the two parallel 

 conductors of a single-phase transmission line. What effect does this 

 field have on the operation of the line? 



8. ( >n what two factors does the inductance of such a line depend? Dis- 

 tinguish between the inductance of the circuit loop and thatof a single wire. 



9. Sketch the magnetic field which may exist at some particular instant 

 in the region between the three conductors of a three-phase transmission 

 line, these conductors being symmetrically spaced. What is the L 

 nature of the fiel- i n t his region and what is its effect on the op' 



of the transmission system? 



10. On what three factors does the reactance per conductor of a three- 

 phase system depend ? 



11. Sketch the electrostatic field which exists between the two cone 



of a single-phase transmission system. On what two factors does the 

 capacitance existing between two such wires depend'.' 



12. Show that a thin fictitious plane may be inserted midway be 



irallel wires and perpendicular to their plane without disturbing 

 the el field between these conductors. With this as a basis, 



replace the capacitance between conductors by two series-con' 

 condensers. What tlO of the capacitance of each of these COn- 



rs to tin- -twcen the line conductors? 



13. Kepi Mial capacitance which exists between .-:illy- 

 spaced three-phase lines by two different arrangements of condensers. 

 Which of ' irrangrin, msidered and I 



14. What do-e approximation ax ' be used uh.-n trans- 

 mission conductors are not located at the corners of an equilateral triangle? 



16. State wiine of the advantages of splitting a single-phase transmission 



u the <ji; utral when 



working out the line eharart, 



16. V .d as having no resistance and no 

 induct is actuall 



17. (live,, the lii, 'he load voltm 



nnd p.. icans of a method of ob- 



taining the voltage at th- sendinc ' "d 



