NON-SINUSOIDAL WAVES 133 



plied with the switch closed? What are the voltages across the 

 condensers before and after the switch is closed? What is the 

 voltage across the reactor after the switch is closed? 



33. Three equal lamp loads each of which has a resistance of 

 ") ohms are connected in Y across the lines of a balanced 230-volt, 

 3-phase circuit. Due to harmonics the voltages from the lines to 

 the neutral conductor of the < -ircuit are each 140 volts. The 

 n<wer supplied is measured by the two-wattmeter mrth<><l. 



(a) What are the line currents and the wattmeter readings? 



(b) If the neutral point of the load is connected to the neutral 

 ei .mliiet or what will the wattmeters read? What is the power 

 supplied? Compare the true power factor of this load with that 

 calculated from the wattmeter, voltmeter, and ammeter reading. 



34. Three unequal lamp loads are connected between the line- 

 ami the neutral conductor of a balanced 230-volt, 3-phase circuit 

 Due to third and fifth harmonics, which are respectively 0.3 and. 

 0.25 of the fundamental, the voltages from the lines to the neutral 

 conductor are each 140 volts. The effective line currents are 

 20 amperes, 30 amperes and 40 amperes respectively. What is 

 the current in the neutral conductor? 



35. In problem 34 if fuses in the third line and in the neutral 

 conductor blow, what current will the lamp load- take, and what 

 will he t lie voltage across each of them? A nine that the i 



of each lamp circuit is constant. 



36. My mi-take three equal air-core impedance unit- are con- 

 nected in delta across two of the main- and the ncntml conductor 

 of a three-phase. liO-eycle circuit. Kach of these impedance units 

 has a iv-i-tanee of ."> ohm- and reactance ,f 'J ohms at 60 cycle-. 

 The voltage- Let ween the main- and neutral conductor are each 



140 Voit-. ;md the voltage between any tWO of the main- 



\-ume that there are no harmonic- higher than the third 



i'. What are the eiirreni- m each of the impedance units'.' 



the current- in the main- and in the neutral conductor? 



37. Two suitable transformers are arranged after the Scott 

 method of connection to transform from 2-phase to 3-phase. 

 Kach of the two-pha-e lino voltages is 2200 volts and consists of 

 a fundamental and a third harmonic which is 30 per cent, of the 



fundamental. The M-pha-' 111 ach have an effect m 



value of 230 volts. The frequency of the fundamental is 60 



cycles. Neglect the resistance and th- reactance of the 

 '.rrners. 



