For radiant heating around 2250°C, the heating elements are made of____________?
A. copper alloy
B. carbon
C. tungsten alloy
D. stainless steel alloy
Month: December 2018
The electrode of a direct arc furnace is made of____________?
The electrode of a direct arc furnace is made of____________?
A. tungsten
B. graphite
C. silver
D. copper
In direct arc furnace, which of the following has high value ?
In direct arc furnace, which of the following has high value ?
A. Current
B. Voltage
C. Power factor
D. All of the above
In a domestic cake baking oven the temperature is controlled by________________?
In a domestic cake baking oven the temperature is controlled by________________?
A. voltage variation
B. thermostat
C. auto-transformer
D. series-parallel operation
Due to which of the following reasons it is desirable to have short arc length ?
Due to which of the following reasons it is desirable to have short arc length ?
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
In an electric press mica is used_____________?
In an electric press mica is used_____________?
A. as an insulator
B. as a device for power factor improvement
C. for dielectric heating
D. for induction heating
By the use of which of the following, high frequency power supply for induction furnaces can be obtained ?
By the use of which of the following, high frequency power supply for induction furnaces can be obtained ?
A. Coreless transformers
B. Current transformers
C. Motor-generator set
D. Multi-phase transformer
The temperature inside a furnace is usually measured by which of the following ?
The temperature inside a furnace is usually measured by which of the following ?
A. Optical pyrometer
B. Mercury thermometer
C. Alcohol thermometer
D. Any of the above
Which of the following insulating materials was suitable for low temperature applications ?
Which of the following insulating materials was suitable for low temperature applications ?
A. Asbestos paper
B. Diatomaceous earth
C. 80 percent magnesia
D. Cork
The material of the heating element for a furnace should have___________?
The material of the heating element for a furnace should have___________?
A. lower melting point
B. higher temperature coefficient
C. high specific resistance
D. all of the above