measurement instruments power energy measurement two wattmeter method ammeter voltmeter multimeter megger energy meter cro ct pt earth fault detection - One Line Questions

1. The standard secondary current rating for most CTs is: — 5 A
2. The standard secondary voltage rating for most PTs is: — 110 V
3. A series R-L circuit has a phase angle of 60 degrees. If a wattmeter measures 1000 W, what is the apparent power? — 2000 VA
4. Which type of meter is primarily used to measure the quantity of electrical energy consumed over a period of time? — Energy Meter
5. The most common instrument for measuring earth resistance is the: — Earth Tester (Megger can also be used)
6. Which device is used to measure insulation resistance of electrical machines and cables? — Megger
7. In a DC circuit, a wattmeter measures: — Active power
8. The CRO displays a graph of voltage versus ______. — Time
9. A universal motor is a type of motor that can run on: — Both AC and DC supplies
10. Which type of energy meter uses a rotating disc driven by eddy currents induced by voltage and current coils? — Electromechanical Induction Type Energy Meter
11. If, in the two-wattmeter method for a balanced three-phase load, the power factor is unity, the readings of the two wattmeters are: — Equal
12. A voltmeter can be converted into an ammeter by connecting a ______ resistance in ______ with it. — Low, parallel
13. The 'Y-gain' or 'Volts/Div' control on a CRO adjusts the: — Vertical sensitivity (voltage per division)
14. Earth fault detection is crucial for: — Ensuring electrical safety and preventing shocks
15. A wattmeter measures: — Average power
16. A dynamometer type wattmeter is preferred for measuring power in AC circuits because it: — Is independent of frequency and waveform
17. The secondary winding of a CT should never be opened when the primary is energized because: — It can damage the CT due to excessive voltage
18. An energy meter measures energy in: — Kilowatt-hours
19. In a three-phase system, if one wattmeter reads negative in the two-wattmeter method, it indicates that the power factor is: — Less than 0.5 (leading or lagging)
20. An ammeter can be converted into a voltmeter by connecting a ______ resistance in ______ with it. — High, series
21. In a Cathode Ray Oscilloscope (CRO), the electron beam is deflected by: — Both magnetic and electric fields
22. A Megger typically uses a ______ generator to produce a high DC voltage for insulation testing. — Hand-driven permanent magnet
23. Which instrument is used to display the waveform of an electrical signal and analyze its characteristics? — Oscilloscope (CRO)
24. A common method for detecting an earth fault involves monitoring the current flowing through the: — Earth conductor
25. Which method is generally preferred for measuring power in a balanced three-phase circuit? — Two-wattmeter method
26. Earth resistance measurement is critical for: — Ensuring the proper functioning of lightning arresters
27. An ammeter is always connected in ______ with the circuit element whose current is to be measured. — Series
28. In the two-wattmeter method for a balanced three-phase load, if the load is purely inductive, the reading of one wattmeter will be: — Positive and the other negative
29. A voltmeter is always connected in ______ with the circuit element across which the voltage is to be measured. — Parallel
30. The primary winding of a PT is connected in ______ with the high voltage line. — Parallel
31. The two-wattmeter method is used to measure the total power in a: — Three-phase balanced load
32. The braking magnet in an energy meter is usually made of: — Alnico
33. Which instrument provides a visual representation of voltage signals over time? — Oscilloscope
34. A Potential Transformer (PT) is used to: — Step down high voltages to a lower, measurable level
35. A Current Transformer (CT) is used to: — Step down high currents to a lower, measurable level
36. A CT is essentially a ______ transformer. — Step-down current
37. A PT is essentially a ______ transformer. — Step-down voltage
38. The 'creeping' effect in an energy meter refers to: — The slow rotation of the disc when only voltage is applied
39. In a three-phase unbalanced load, the sum of the readings of two wattmeters in the two-wattmeter method gives: — The total active power
40. What is the primary purpose of using a CT and PT in power systems? — To measure high voltages and currents safely using standard low-range instruments
41. What is the primary function of a Megger? — To measure high resistance, especially insulation resistance
42. The 'Time Base' control on a CRO adjusts the: — Horizontal sweep speed
43. The 'X-gain' or 'Time/Div' control on a CRO adjusts the: — Horizontal sweep speed (time per division)
44. The internal resistance of an ideal ammeter should be: — Zero
45. In an induction type energy meter, the speed of the disc is proportional to the: — Power
46. To compensate for the creeping effect in an energy meter, a small hole is often drilled in the: — Disc
47. A multimeter is a versatile instrument that can measure: — Voltage, Current, and Resistance
48. Which instrument measures the rate of alternation of current or voltage? — Frequency Meter
49. The unit of electrical energy is typically measured in: — Kilowatt-hours (kWh)
50. The internal resistance of an ideal voltmeter should be: — Very high
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