91. Which value of flux is invloved in the emf equation of the transformer
a. Maximum value
b. Average value
c. RMS value
d. Critical value
92. A 11 KV transformer is subjected to 1 minute. 50 Hz, lower frequency test voltage
a. 11 KV peak
b. 12 KV rms
c. 28 KV rms
d. 110 KV rms
93. Harmonic currents in a transformer cause
a. increased I square R loss
b. increased core loss
c. magnetic interference with protective relays
d. all of the above
94. Which of the following is the most likely source of harmonics in a transformer?
a. Over load
b. Core saturation
c. Poor insulation. Loose connections
95. A 100 W 220 V meandenscent bulb is connected in series with the primary of a 220 v , 20 KVA transformer . when the secondary of the transformer is open circuited. the bulb will
a. not glow
b. glow with less than normal brightness
c. glow with more than normal brightness
d. glow with more than normal brightness
96. In scott connections the main transormer has centre tap on
a. primary windings
b. secondary windings
c. both primary and secondary windings
97. A tap changer is used on a transformer for
a. adjustment in primary voltage
b. adjustment in secondary voltage
c. adjustment in both primary and secondary voltages
d. adjustment in power factor
98.Over current in a transformer affect
a. insulation life
b. temperature rise
c. mechanical stress
d. all of the above
99. The transformer has 50 watt
a. hysteresis loss
b. eddy current loss
c. core loss
d. copper loss
100. In a transformer the tapping are usually provided
a. primary side
b. secondary side
c. low voltage side
d. high voltage side
