Radiations from a black body are proportional to____________?
A. T1
B. T2
C. T3
D. T*
A. To avoid initial rush of current
B. To avoid change in kW rating with temperature
C. Both (A) and (B)
D. Either (A) or (B)
It is desirable to operate the arc furnaces at power factor of_____________?
A. zero
B. 0.707 lagging
C. unity
D. 0.707 leading
Ajax Wyatt furnace is started when____________?
A. it is filled below core level
B. it is filled above core level
C. it is fully empty
D. none of the above
Which of the following methods is used to control temperature in resistance furnaces ?
A. Variation of resistance
B. Variation of voltage
C. Periodical switching on and off of the supply
D. All of the above methods
In arc furnace the function of choke is______________?
A. to stabilize the arc
B. to imprpve, power factor
C. to reduce severity of the surge
D. none of the above