A. To achieve better heating
B. To increase the life of roof refractory
C. To have better stirring action
D. To reduce problem of oxidation
E. All of the above
Related Mcqs:
- It is desirable to operate the arc furnaces at power factor of_____________?
A. zero
B. 0.707 lagging
C. unity
D. 0.707 leading - Properly of low temperature co-eflficient of heating element is desired due to which of the following reasons ?
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) - By which of the following methods the temperature inside arc nace can be varied ?
A. By disconnecting some of the heating elements
B. By varying the operating voltage
C. By varying the current through heating elements
D. By any of the above method - In direct arc furnace, which of the following has high value ?
A. Current
B. Voltage
C. Power factor
D. All of the above - Direct arc furnaces have which of the following power factors ?
A. Unity
B. Low, lagging
C. Low, leading
D. Any of the above - The electrode of a direct arc furnace is made of____________?
A. tungsten
B. graphite
C. silver
D. copper - 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 - In heating the ferromagnetic material by induction heating, heat is produced due to_____________?
A. induced current flow through the charge
B. hysteresis loss taking place below curie temperature
C. due to hysteresis loss as well as eddy current loss takingplace in the charge
D. none of the above factors - Induction heating takes place it which of the following ?
A. Insulating materials
B. Conducting materials which are magnetic
C. Conducting materials which are non-magnetic
D. Conducting materials which may or may not be magnetic - Which of the following insulating materials was suitable for low temperature applications ?
A. Asbestos paper
B. Diatomaceous earth
C. 80 percent magnesia
D. Cork
