SSC JE Exam - measurement instruments power energy measurement two wattmeter method ammeter voltmeter multimeter megger energy meter cro ct pt earth fault detection Online Test (MCQ Quiz)

1. Which type of meter is primarily used to measure the quantity of electrical energy consumed over a period of time?

A) Ammeter B) Voltmeter C) Energy Meter D) Wattmeter

2. The two-wattmeter method is used to measure the total power in a:

A) Single-phase balanced load B) Single-phase unbalanced load C) Three-phase balanced load D) Three-phase unbalanced load

3. In the two-wattmeter method for a balanced three-phase load, if the load is purely inductive, the reading of one wattmeter will be:

A) Positive and the other negative B) Zero C) Equal to the total power D) Half of the total power

4. An ammeter is always connected in ______ with the circuit element whose current is to be measured.

A) Parallel B) Series C) Perpendicular D) Any of the above

5. A voltmeter is always connected in ______ with the circuit element across which the voltage is to be measured.

A) Series B) Parallel C) Delta D) Star

6. A multimeter is a versatile instrument that can measure:

A) Voltage, Current, and Resistance B) Voltage, Power, and Frequency C) Current, Resistance, and Inductance D) Voltage, Resistance, and Capacitance

7. What is the primary function of a Megger?

A) To measure low resistance B) To measure high resistance, especially insulation resistance C) To measure AC voltage D) To measure frequency

8. A Megger typically uses a ______ generator to produce a high DC voltage for insulation testing.

A) Moving coil B) Moving iron C) Hand-driven permanent magnet D) Dynamically coupled

9. The unit of electrical energy is typically measured in:

A) Watts B) Volts C) Joules D) Kilowatt-hours (kWh)

10. A wattmeter measures:

A) Instantaneous power B) Average power C) Apparent power D) Reactive power

11. Which instrument is used to display the waveform of an electrical signal and analyze its characteristics?

A) Multimeter B) Oscilloscope (CRO) C) Energy Meter D) Frequency Meter

12. In a Cathode Ray Oscilloscope (CRO), the electron beam is deflected by:

A) Magnetic fields only B) Electric fields only C) Both magnetic and electric fields D) Mechanical actuators

13. A Current Transformer (CT) is used to:

A) Step up voltage for measurement B) Step down voltage for measurement C) Step down high currents to a lower, measurable level D) Step up low currents to a higher, measurable level

14. The secondary winding of a CT should never be opened when the primary is energized because:

A) It can damage the CT due to excessive voltage B) It can cause a fire hazard C) It can lead to a short circuit D) It will stop current flow

15. A Potential Transformer (PT) is used to:

A) Step up low voltages to a higher, measurable level B) Step down high voltages to a lower, measurable level C) Measure current D) Measure power factor

16. The primary winding of a PT is connected in ______ with the high voltage line.

A) Series B) Parallel C) Delta D) Star

17. Earth fault detection is crucial for:

A) Improving power factor B) Ensuring electrical safety and preventing shocks C) Increasing system efficiency D) Reducing voltage fluctuations

18. Which type of energy meter uses a rotating disc driven by eddy currents induced by voltage and current coils?

A) Digital Energy Meter B) Electromechanical Induction Type Energy Meter C) Smart Energy Meter D) Mechanical Counter Meter

19. The 'creeping' effect in an energy meter refers to:

A) The slow rotation of the disc when only voltage is applied B) The fast rotation of the disc when load is disconnected C) The disc not rotating at all D) The disc rotating backwards

20. To compensate for the creeping effect in an energy meter, a small hole is often drilled in the:

A) Voltage coil B) Current coil C) Disc D) Braking magnet

21. A dynamometer type wattmeter is preferred for measuring power in AC circuits because it:

A) Is less expensive B) Has a linear scale C) Is independent of frequency and waveform D) Is easier to manufacture

22. In a three-phase unbalanced load, the sum of the readings of two wattmeters in the two-wattmeter method gives:

A) The total active power B) The total apparent power C) The total reactive power D) The average power

23. If, in the two-wattmeter method for a balanced three-phase load, the power factor is unity, the readings of the two wattmeters are:

A) Equal B) One is double the other C) One is zero D) Unequal

24. The internal resistance of an ideal voltmeter should be:

A) Zero B) Very low C) Very high D) Infinite

25. The internal resistance of an ideal ammeter should be:

A) Very high B) Infinite C) Zero D) Very low

26. A universal motor is a type of motor that can run on:

A) DC supply only B) AC supply only C) Both AC and DC supplies D) Three-phase AC supply only

27. Which instrument provides a visual representation of voltage signals over time?

A) Spectrum Analyzer B) Frequency Counter C) Oscilloscope D) Logic Analyzer

28. The 'Time Base' control on a CRO adjusts the:

A) Vertical sensitivity B) Horizontal sweep speed C) Intensity of the beam D) Focus of the spot

29. A CT is essentially a ______ transformer.

A) Step-up voltage B) Step-down voltage C) Step-up current D) Step-down current

30. The standard secondary current rating for most CTs is:

A) 1 A B) 5 A C) 10 A D) 0.1 A

31. A PT is essentially a ______ transformer.

A) Step-up voltage B) Step-down voltage C) Step-up current D) Step-down current

32. The standard secondary voltage rating for most PTs is:

A) 110 V B) 220 V C) 440 V D) 12 V

33. Earth resistance measurement is critical for:

A) Optimizing power transmission B) Ensuring the proper functioning of lightning arresters C) Preventing over-voltage conditions D) Reducing harmonic distortion

34. The most common instrument for measuring earth resistance is the:

A) Ammeter B) Voltmeter C) Earth Tester (Megger can also be used) D) Wattmeter

35. In an induction type energy meter, the speed of the disc is proportional to the:

A) Voltage B) Current C) Power D) Energy

36. The braking magnet in an energy meter is usually made of:

A) Soft iron B) Alnico C) Copper D) Aluminum

37. A series R-L circuit has a phase angle of 60 degrees. If a wattmeter measures 1000 W, what is the apparent power?

A) 500 VA B) 1000 VA C) 2000 VA D) 1500 VA

38. Which device is used to measure insulation resistance of electrical machines and cables?

A) Ammeter B) Voltmeter C) Megger D) Multimeter

39. In a three-phase system, if one wattmeter reads negative in the two-wattmeter method, it indicates that the power factor is:

A) Leading and greater than 0.5 B) Lagging and greater than 0.5 C) Less than 0.5 (leading or lagging) D) Unity

40. The CRO displays a graph of voltage versus ______.

A) Current B) Time C) Resistance D) Power

41. What is the primary purpose of using a CT and PT in power systems?

A) To increase power transmission efficiency B) To measure high voltages and currents safely using standard low-range instruments C) To protect the system from overloads D) To regulate voltage levels

42. A voltmeter can be converted into an ammeter by connecting a ______ resistance in ______ with it.

A) High, series B) Low, parallel C) High, parallel D) Low, series

43. An ammeter can be converted into a voltmeter by connecting a ______ resistance in ______ with it.

A) Low, parallel B) High, series C) Low, series D) High, parallel

44. The 'Y-gain' or 'Volts/Div' control on a CRO adjusts the:

A) Horizontal sweep speed B) Vertical sensitivity (voltage per division) C) Intensity of the beam D) Focus of the spot

45. Which method is generally preferred for measuring power in a balanced three-phase circuit?

A) One-wattmeter method B) Two-wattmeter method C) Three-wattmeter method D) Single-phase wattmeter measurement

46. The 'X-gain' or 'Time/Div' control on a CRO adjusts the:

A) Vertical sensitivity B) Horizontal sweep speed (time per division) C) Intensity of the beam D) Focus of the spot

47. An energy meter measures energy in:

A) Joules B) Watt-seconds C) Kilowatt-hours D) Kilojoules

48. A common method for detecting an earth fault involves monitoring the current flowing through the:

A) Neutral conductor B) Phase conductors C) Earth conductor D) Busbars

49. Which instrument measures the rate of alternation of current or voltage?

A) Wattmeter B) Energy Meter C) Frequency Meter D) Power Factor Meter

50. In a DC circuit, a wattmeter measures:

A) Apparent power B) Reactive power C) Active power D) Peak power

measurement instruments power energy measurement two wattmeter method ammeter voltmeter multimeter megger energy meter cro ct pt earth fault detection - Online Test

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