Electrical Engineering (EE) Exam > Electrical Engineering (EE) Questions > Assertion (A): An electrodynamometer type wat...
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Assertion (A): An electrodynamometer type wattmeter reads low when the load power factor is leading.
Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.
Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.
- a)Both A and R are true and R is a correct explanation of A.
- b)Both A and R are true but R is not a correct explanation of A.
- c)A is true but R is false.
- d)A is false but R is true.
Correct answer is option 'A'. Can you explain this answer?
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Assertion (A): An electrodynamometer type wattmeter reads low when the...
InIn the above phasor diagram
I = load current and
IP = Pressure coil current
We know that, measured power is
At leading power factor of load, angle (φ + β) is increased, therefore cos(φ + β) is reduced. Hence, wattmeter reads low at leading p.f, load.
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Assertion (A): An electrodynamometer type wattmeter reads low when the...
Assertion (A): An electrodynamometer type wattmeter reads low when the load power factor is leading.
Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.
Explanation:
A is true because an electrodynamometer type wattmeter is designed to measure the real power in a circuit. In a circuit with a leading power factor, the wattmeter will read low due to the effect of inductive reactance in the pressure coil.
R is a correct explanation of A because when the load power factor is leading, there is a phase difference between the current flowing through the load and the current flowing through the pressure coil of the wattmeter. The inductance of the pressure coil causes a lagging current, which increases the phase angle between the load current and the pressure coil current. This leads to an error in the measurement of real power by the wattmeter.
To understand this concept more clearly, let's break down the explanation into key points:
1. Electrodynamometer Type Wattmeter:
- An electrodynamometer type wattmeter is a type of instrument used to measure the real power in a circuit.
- It works on the principle of the interaction between the magnetic field produced by the current in the pressure coil and the magnetic field produced by the current in the current coil.
2. Leading Power Factor:
- In a circuit with a leading power factor, the current leads the voltage waveform.
- This means that the current waveform reaches its peak before the voltage waveform.
3. Effect of Pressure Coil Inductance:
- The pressure coil of the electrodynamometer type wattmeter has inductance due to the presence of a coil.
- Inductance causes a phase lag between the current and voltage waveforms.
- When the load power factor is leading, the phase angle between the load current and the pressure coil current increases.
- This increased phase angle causes the wattmeter to read low.
Conclusion:
Both Assertion (A) and Reason (R) are true, and Reason (R) is a correct explanation of Assertion (A). The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading, leading to a low reading on the electrodynamometer type wattmeter.
Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.
Explanation:
A is true because an electrodynamometer type wattmeter is designed to measure the real power in a circuit. In a circuit with a leading power factor, the wattmeter will read low due to the effect of inductive reactance in the pressure coil.
R is a correct explanation of A because when the load power factor is leading, there is a phase difference between the current flowing through the load and the current flowing through the pressure coil of the wattmeter. The inductance of the pressure coil causes a lagging current, which increases the phase angle between the load current and the pressure coil current. This leads to an error in the measurement of real power by the wattmeter.
To understand this concept more clearly, let's break down the explanation into key points:
1. Electrodynamometer Type Wattmeter:
- An electrodynamometer type wattmeter is a type of instrument used to measure the real power in a circuit.
- It works on the principle of the interaction between the magnetic field produced by the current in the pressure coil and the magnetic field produced by the current in the current coil.
2. Leading Power Factor:
- In a circuit with a leading power factor, the current leads the voltage waveform.
- This means that the current waveform reaches its peak before the voltage waveform.
3. Effect of Pressure Coil Inductance:
- The pressure coil of the electrodynamometer type wattmeter has inductance due to the presence of a coil.
- Inductance causes a phase lag between the current and voltage waveforms.
- When the load power factor is leading, the phase angle between the load current and the pressure coil current increases.
- This increased phase angle causes the wattmeter to read low.
Conclusion:
Both Assertion (A) and Reason (R) are true, and Reason (R) is a correct explanation of Assertion (A). The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading, leading to a low reading on the electrodynamometer type wattmeter.
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Assertion (A): An electrodynamometer type wattmeter reads low when the load power factor is leading.Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.a)Both A and R are true and R is a correct explanation of A.b)Both A and R are true but R is not a correct explanation of A.c)A is true but R is false.d)A is false but R is true.Correct answer is option 'A'. Can you explain this answer?
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Assertion (A): An electrodynamometer type wattmeter reads low when the load power factor is leading.Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.a)Both A and R are true and R is a correct explanation of A.b)Both A and R are true but R is not a correct explanation of A.c)A is true but R is false.d)A is false but R is true.Correct answer is option 'A'. Can you explain this answer? for Electrical Engineering (EE) 2024 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about Assertion (A): An electrodynamometer type wattmeter reads low when the load power factor is leading.Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.a)Both A and R are true and R is a correct explanation of A.b)Both A and R are true but R is not a correct explanation of A.c)A is true but R is false.d)A is false but R is true.Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Assertion (A): An electrodynamometer type wattmeter reads low when the load power factor is leading.Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.a)Both A and R are true and R is a correct explanation of A.b)Both A and R are true but R is not a correct explanation of A.c)A is true but R is false.d)A is false but R is true.Correct answer is option 'A'. Can you explain this answer?.
Assertion (A): An electrodynamometer type wattmeter reads low when the load power factor is leading.Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.a)Both A and R are true and R is a correct explanation of A.b)Both A and R are true but R is not a correct explanation of A.c)A is true but R is false.d)A is false but R is true.Correct answer is option 'A'. Can you explain this answer? for Electrical Engineering (EE) 2024 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about Assertion (A): An electrodynamometer type wattmeter reads low when the load power factor is leading.Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.a)Both A and R are true and R is a correct explanation of A.b)Both A and R are true but R is not a correct explanation of A.c)A is true but R is false.d)A is false but R is true.Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Assertion (A): An electrodynamometer type wattmeter reads low when the load power factor is leading.Reason (R): The effect of pressure coil inductance is to increase the phase angle between load current and pressure coil current when the load power factor is leading.a)Both A and R are true and R is a correct explanation of A.b)Both A and R are true but R is not a correct explanation of A.c)A is true but R is false.d)A is false but R is true.Correct answer is option 'A'. Can you explain this answer?.
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