Question

52. In three-phase power systems, the delivered power a. falls to zero three times per cycle b. falls to zero once per cycle c. never falls to zero d. none of the above 53. The three-phase connection in which one end of each of the windings are connected together is called the connection. a. delta b. wye c. open delta d. open wye 54. In a three phase connection, the voliage meaured direety across one of the winings is the votage a. line b. phase In a three-phase connection, the current that flows in an externally connected voltage conductor is the 55. current. a. line b. phase Line current and phase current are the same in the configuration. 56, a. delta b. wye Line voltage and phase voltage are the same in the 57. a. delta b. wye 58. A delta connected set of windings has a phase voltage of 480 V. What is the value of the line voltage? a. 277.14 V b. 480 V c. 831.36 V d. 1440 V -59. In a three-phase circuit, the true power (watts) is found by multiplying line voltage by line current multiplying apparent power by the power factor dividing power factor by the apparent power multiplying phase voltage by phase current a. b. c. d. 60. In calculating power in a three-phase circuit, the product of line voltage and line current and power factor are multiplied by a. three b. square root of three 61. The magnetically operated device that can change values of voltage, current, and impedance without changing frequency is the a. converter b. inverter c. transformer d. transistor

Answer 1

Never falls to zero wye phase line wye delta 480 squareroot of three transformer p = squareroot 3 v_L I_L cos pi