-TIONS AND /' 



47 



62. Three resistances of 70 ohms each are connected in Y across a 3-phase 

 230-volt supply. How much current does each take and what is the total 

 power taken by the three? 



53. If the three resistances of problem 52 are connected in delta, how 

 much current does each take and what is the line current? Determine the 

 total power and compare it with that obtained in problem 52. 



64. Three condensers each have a capacitance of 40 mf. Compare the 

 kv-a. that they take when connected in Y and then in delta across the 230- 

 volt. three-pha>e. recycle mains. 



65. A certain three-phase induction motor takes 30 kw. at 550 volte. 

 The line current is 40 amp. What is the power-factor of this motor? 

 What is the angle between the coil current and the coil voltage? 



56. The electromotive forces generated in two alternator coils differ 120 

 in phase. When the end of one coil is connected to an end of the other, the 

 voltage across their open ends is 190 volts. If the voltage of each coil is 

 190 volts, what will be the voltage across their open ends if one coil is 

 reversed? 



Alternator 



I !., 



57. In the test of a 230-volt, 3-phiuse induction motor the two-wattmeter 

 method of measuring power is employed. One wattmeter reads + 4,350 

 watts and the other reads + 2,200 watte. (n) What is the motor ; 

 factor at this load? (6) What i> the line oumnt? () What i> t! 

 phase angle? 



58. At light load on the mo' Mem :.:. the first wattmeter reads 

 1,820 watte and the second - l.V) \v:n- v\ hat i-. the mmor power- 

 factor and the line current at this |. 'he coil pha.c-angle ' 



69. Ivtch of the two ,-oiU ,,| :,,, ;, 1 1 rnia t < T geMffttM 2,800 Volts End 

 these Voltages differ in phase by '.M). If these two coils are connected tO- 



points and tin with the < 



indicate all the voltages that can be obtained. 



60. (<i If the tuo coil- of problem 59 arc connected togrt .c end, 



Ifl the voltntfe MfOflq the Op (M If th- per cod IS 



he three wires 1< <m the 



mach i, power does the grn 



power-factor? 



