Circuit Breakers and Relays 4

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Objectives for Electrician and Wireman: Circuit Breakers and Relays 4

Subject: Circuit Breakers and Relays 4

Part 4: Objective questions and answers of Circuit Breakers and Relays


Q1. The device which is capable of marking and braking a circuit under normal as well as abnormal condition is called as……

a) High Rupturing Capacity (HRC) Fuse

b) Switch Fuse Unit

c) Circuit Breaker

d) Electrical Reset Relays


Q2. In circuit breaker, the maximum power that a circuit breaker can safely interrupt under a fault is known as….

a) Maximum operating power

b) Minimum operating power

c) Breaking capacity

d) Rupturing capacity


Q3. MCCB stands for…….

a) Miniature Current Circuit Breaker

b) Maximum Current Circuit Breaker

c) Moulded Cabinet Circuit Breaker

d) Moulded Case Circuit Breaker


Q4. Which device is used to protect the circuits from short circuit fault?

a) Switch

b) MCB

c) Meter

d) Isolator


Q5. For air conditioners of 1.5-ton capacity, sockets with MCB rating are……

a) 16 A

b) 18 A

c) 20 A

d) 22 A


Q6. What will happen when 12 v, 50 hz A.C. Relay is connected to a 12 v D.C. Supply?

a) The switching speed will be increased because of more current drawn by relay

b) The switching capacity of the relay will be decreased very strongly

c) The relay draws more current in the absence of inductive reactance, which burns out the coil

d) D.C. Operation causes the core and armature to become partly permanent magnet and fails to function after a few operations


Q7. Which type of relay is used to protect the damage of equipment during under and over voltage fault?

a) Current sensing relay

b) Under current relay

c) Voltage sensing relay

d) Latching relay


Q8. Which type of relay is used as time-delay relays?

a) Impulse relay

b) Dry reed relay

c) Thermal relay

d) Free relay


Q9. The purpose of a shading coil placed near the tip of the magnet pole face of relay is to…….

a) Eliminate the chattering noise in relay

b) Protect the equipment from fluctuating voltage

c) Provide the gap between the layers of magnetic core

d) Increase the strength of the magnetic field


Q10. The protective relay is specified as ‘4pdt’ contact. What is the full form of it?

a) 4 point double time delay contact

b) 4 pole double throw contact

c) 4 package double throw contact

d) 4 pole double time delay contact


Q11. The integrated circuit voltage regulator is designated as ‘7912’. What does the number ’79’ indicate?

a) Positive output regulator

b) Negative output regulator

c) Positive output voltage

d) Negative output voltage


Q12. A resistor is used in an electric circuit for

a) Blocking the flow of current

b) Increasing the flow of current

c) Reducing the flow of current

d) None of the above


Q13. For measuring insulation resistance, the best choice would be

a) Digital multimeter

b) Megger

c) Multimeter

d) Wheat Stone Bridge


Q14. Potentiometers of wire-wound type are made in

a) Rotary type only

b) Sliding contact type only

c) Both rotary and sliding contact types

d) Preset type


Q15. A preset is a sort of

a) Variable resistor

b) Adjustable resistor

c) Fixed value resistor

d) Stepped value resistor


Q16. Carbon resistors are made in

a) Composition type only

b) Film type only

c) Both composition and film types

d) None of the above stated types


Q17. What is the value of the resistor which is having the colour bands in the order of red, green, orange and gold respectively?

a) 24000 ohms +/- 10%

b) 25000 ohms +/- 5%

c) 26000 ohms +/- 10%

d) 27000 ohms +/- 5%


Q18. T.W. board for fixing main switches sizes available is: (LENGTH x BREADTH)

a) 80 mm x 80 mm

b) 85 mm x 85 mm

c) 90 mm x 90 mm

d) 100 mm x 100 m


Q19. The process of limiting high frequencies is called?

a) Pre-emphasis

b) De-emphasis

c) Tuning

d) None of the above


Q20. Speaker used for the reproduction of high audio frequencies above 3 khz in Hi-Fi audio system is called?

a) Tweeter

b) Woofer

c) Squaker

d) Booster


Part 4: Objective questions and answers of Circuit Breakers and Relays


Q1. Answer c


Q2. Answer d


Q3. Answer d


Q4. Answer b


Q5. Answer c


Q6. Answer c


Q7. Answer c


Q8. Answer c


Q9. Answer a


Q10. Answer b


Q11. Answer d


Q12. Answer c


Q13. Answer b


Q14. Answer c


Q15. Answer b


Q16. Answer c


Q17. Answer b


Q18. Answer d


Q19. Answer a


Q20. Answer a

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