This set of Design of Electrical Machines Interview Questions and Answers focuses on “Temperature Rise and Insulating Materials”.
1. How many number of insulation classes are present with respect to electrical equipment?
a) 5
b) 6
c) 7
d) 8
View Answer
Explanation: There are 7 classes of insulation with respect to electrical equipment. They are Class Y, Class A, Class E, Class B, Class F, Class H, Class C.
2. How many classes have their temperatures above 100°C?
a) 5
b) 6
c) 7
d) 8
View Answer
Explanation: There are 7 insulation classes present in relation with temperature. Of the 7 classes, there are 6 classes whose temperatures are greater than 100°C. Class Y is the only class having temperature less than 100.
3. How many classes have their temperatures above 150°C?
a) 2
b) 3
c) 4
d) 5
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Explanation: Of 7 classes of insulation, there are 3 classes whose temperatures are above 150°C. They are classes F, H, C of insulation.
4. Which class has the lowest and the highest temperature?
a) Class Y, Class C
b) Class Y, Class H
c) Class H, Class C
d) Class B, Class H
View Answer
Explanation: Class Y belongs to the lowest insulation class of having temperature of about 90°C. Class C is the highest insulation class of having temperature above 180°C.
5. Class A has higher temperature than Class E.
a) True
b) False
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Explanation: Class E has a higher temperature than that of Class A. The temperature of Class A is 105°C and the temperature of Class E is 120°C.
6. What is the temperature of Class B?
a) 120°C
b) 130°C
c) 155°C
d) 180°C
View Answer
Explanation: 120°C refers to the temperature of Class E. 155°C refers to the temperature of Class F. 180°C refers to the temperature of Class H.
7. Which among the following is the example of Class Y?
a) Varnish
b) Insulation oil
c) Paper
d) Resins
View Answer
Explanation: Varnish is an example of Class A. Even insulation oil is an example of Class A. Resins is an example of Class E.
8. Which among the following is the example of Class B?
a) Inorganic material with adhesives
b) Hard fiber
c) Wood
d) Impregnated oil
View Answer
Explanation: Impregnated oil is the example of Class H. Hard Fiber is the example of Class Y and Wood is the example of Class A.
9. Which among the following is an example of Class F?
a) Paper lamination
b) Nitrile rubber
c) Asbestos
d) Silicone
View Answer
Explanation: Paper lamination is the example of Class E. Nitrile Rubber is the example of Class A. Asbestos is the example of Class B.
10. Silicone rubber is an example of Class H.
a) True
b) False
View Answer
Explanation: Class H is one of the insulation classes having temperature about 180°C. Silicone rubber is one of the examples of Class H.
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