51. The square wave operation of 3 phase VSI lines contains the harmonics. The amplitudes are
52. The switching function of semiconductor devices can be characterized with
53. The triac is .....................
54. The UJT may be used as ............................
55. The V-I characteristics for a triac in the first and third quadrants are essentially identical to those of ........................ in its first quadrant
56. To turn on UJT, the forward bias on the emitter diode should be ...................... the peak point voltage
57. TRIAC is a semiconductor power electronic device which contains
58. Under harmonic free load voltages, the 3 phase VSI
59. Unipolar modulation is generally used in
60. Very large values of modulation index (greater than 3.24 lead to)
61. Voltage commutation circuit can be converted into a current commutation by interchanging the positions of
62. When a UJT is turned ON, the resistance between emitter terminal and lower base terminal.................................
63. When the emitter terminal of a UJT is open, the resistance between the base terminal is generally .......................
64. When the temperature increases, the inter-base resistance (RBB) of a UJT ......................
65. When the temperature increases, the intrinsic stand off ratio ....................
66. Which of the following is not a characteristic of UJT?
67. With increase in firing angle
68. A crowbar is a circuit which is used to protect a
69. A diac has ................... terminals
70. A diac has …………… pn junctions
71. A diac has ……………… semiconductor layers
72. A diac is …………………. switch
73. A diac is simply ………………
74. A diac is turned on by …………………
75. A full wave rectifier with resistive load produces
76. A triac can pass a portion of …………… half-cycle through the load
77. A triac has …………….. semiconductor layers
78. A Triac has three terminals viz ………………
79. A triac is a …………. switch
80. A triac is equivalent to two SCRs …………..
81. A UJT has ……………….
82. A UJT is sometimes called …………. diode
83. AC power in a load can be controlled by using
84. After peak point, the UJT operates in the ……………. region
85. An SCR can be used
86. An SCR is made up of silicon because
87. Between the incoming and outgoing devices in voltage commutation
88. Between the peak point and the valley point of UJT emitter characteristics we have ………….. region
89. Double fourier series analysis of PWM is
90. During the commutation period in 3 phase converter, overlap time is
91. For a buck converter to reduce the conduction losses in diode
92. For bidirectional operation of converters
93. For similar carrier and modulating signals, the line current used in CSI is
94. For sweptfrequency measurements, the input impedance of the mismatched transmission line would vary with frequency as the electrical length ofthe transmission line would
95. Harmonics in 3 phase inverters can be reduced by using
96. In a 3 phaseCSI, if the required line output voltages are balanced and 120 degreeout of phase, then the chopping angles are used to eliminate only theharmonics at frequencies
97. In a load commutated DC – DC chopper, the capacitor has a
98. In a three phase converter, the number of notches per cycle is
99. In a UJT, the p-type emitter is ……………. doped
100. In bipolar modulation, the carrier is symmetric about zero with amplitude equal to Cm, the PWM output
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