Podcast
Questions and Answers
What are the two main reasons for using instrument transformers in measurement?
What are the two main reasons for using instrument transformers in measurement?
- To extend the range of measuring instruments and to isolate them from high-voltage lines (correct)
- To increase accuracy and to reduce cost of instruments
- To decrease power consumption and to reduce size of instruments
- To reduce power loss and to increase the safety of operators
What is the main advantage of using CT over shunts in ac circuits?
What is the main advantage of using CT over shunts in ac circuits?
- CT is cheaper than shunts
- CT does not require careful designing of reactance and resistance proportions (correct)
- CT is more accurate than shunts
- CT is more reliable than shunts
What is a limitation of using shunts for circuits involving large current?
What is a limitation of using shunts for circuits involving large current?
- Shunts are not safe for the operator
- The power loss in the shunt itself will become prohibitively high (correct)
- Shunts are too expensive
- Shunts are not accurate for large currents
What is a problem with using multipliers in measurement?
What is a problem with using multipliers in measurement?
What is an advantage of using instrument transformers with ammeters?
What is an advantage of using instrument transformers with ammeters?
Why are measuring circuits involving shunts or multipliers not safe for the operator?
Why are measuring circuits involving shunts or multipliers not safe for the operator?
What is an advantage of using a suitable multi-range CT or PT with a single-range instrument?
What is an advantage of using a suitable multi-range CT or PT with a single-range instrument?
What is the main difference between a CT and a PT?
What is the main difference between a CT and a PT?
What is the main reason why instrument transformers are used in measurement of voltage, current, energy, and power in ac circuits?
What is the main reason why instrument transformers are used in measurement of voltage, current, energy, and power in ac circuits?
What is a disadvantage of using multipliers in measurement?
What is a disadvantage of using multipliers in measurement?
Study Notes
Instrument Transformers
- Used in measurement of voltage, current, energy, and power in AC circuits
- Two main reasons for use:
- Extend (multiply) the range of measuring instruments
- Isolate measuring instruments from high-voltage lines
Types of Instrument Transformers
- Current Transformer (CT): extends current ranges of instruments
- Voltage or Potential Transformer (PT): increases voltage ranges
Advantages of Instrument Transformers
Over Shunts and Multipliers
- No need for careful design of reactance and resistance proportions for shunts and meters
- Can be used for circuits involving large currents without excessive power loss
- No introduction of errors in measurement due to leakage current
- No unnecessary heating due to power loss
- Electrically isolated from power circuit, ensuring operator safety
- Can cover a wide range of measurements with single-range, moderate-sized instruments
- Can reduce overall cost by connecting multiple instruments to the same instrument transformer
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Description
Learn about the use of instrument transformers in measuring voltage, current, energy, and power in AC circuits. Understand their importance in extending measurement ranges and isolating instruments from high-voltage lines.
