Wattmeter Theory And Measurement of Power - 2 - MCQs

Wattmeter Theory And Measurement of Power - 2 - MCQs

Q1. A dynamometer type wattmeter reads 200W when its voltage coil is connected across the load whose voltage is 150 V. if the voltage coil has internal resistance of 1800 ohm, then the power taken by the load will be

A. 163.8 W
B. 171.7 W
C. 178.9 W
D. 187.5 W

View Answer / Hide Answer

Q2. In a dynamometer type meter, the error due to connections would be minimum if

A. Capacitive reactance of pressure coil is greater than its inductive reactance

B. Capacitive reactance of pressure coil is equal to its inductive reactance

C. Capacitive reactance of pressure coil is lesser than its inductive reactance

D. Capacitive reactance of current coil is equal to its inductive reactance

View Answer / Hide Answer

Q3. To avoid wastage of power during calibration in dynamometer type wattmeter

A. Phantom loading is used
B. Brake magnet is used
C. Spring is used
D. Capacitance is used

View Answer / Hide Answer

Q4. Induction wattmeter’s can be used with

A. Only ac supply
B. Only dc supply
C. Both ac and dc supply
D. None of these

View Answer / Hide Answer

Q5. The frequency and supply voltage of induction wattmeter’s are

A. Constant, constant
B. Constant, variable
C. Variable, constant
D. Variable, variable

View Answer / Hide Answer

Q6. In induction type wattmeter both current and pressure coils are required. For obtaining the required phase difference

A. Shaded pole principle is used
B. Two separate ac magnets are used
C. Only one ac magnets are used
D. All of these

View Answer / Hide Answer

Q7. The scale of induction wattmeter extends over

A. 70 degree
B. 120 degree
C. 180 degree
D. 300 degree

View Answer / Hide Answer

Q8. A wattmeter has a pressure coil resistance of 5K ohm and current coil resistance of 0.02 ohm. What load will give equal error with the two connections if the load current is 15 A at a voltage of 240 V and 0.8 power factor

A. 20 A
B. 24 A
C. 28 A
D. 32 A

View Answer / Hide Answer