Quiz sheet for energy and power requirements in AC systems

Reactive (Quadrature power) is measured in:

A) VArs

B) VA

C) Amps

D) Watts

ANSWER: A

The letter S in the above diagram represents:

A) apparent power

B) slow power

C) reactive power 

D) true power

ANSWER: A

Maximizing power factor in an AC circuit is intended to:

A) minimise the load current.

B) maximise load current.

C) minimise damage to cables

D) reduce vibration

ANSWER: A

The total power in a 3 phase system may be measured using a single fixed wattmeter provided the:

A) the load is balanced

B) the load is not balanced

C) the neutral is not connected

D) it is in series with the load

ANSWER: A

A lagging power factor can be improved without increasing power consumption with the addition of:

A) capacitors

B) inductors 

C) resistors

D) larger size conductors.

ANSWER: A

The minimum number of fixed wattmeters required to measure total power drawn by a 3 phase four wire unbalanced load is:

A) Three

B) One

C) Two

D) Four

ANSWER: A

When measuring balanced 3 phase power with the two wattmeter method and both readings are equal, the power factor is: 

A) unity

B) zero

C) 0.5 leading

D) 0.5 lagging

ANSWER: A

When using a wattmeter to measure power in a 3 phase star connected system, the current coil is connected in:

A) series with the load

B) parallel with the load

C) parallel with the supply

D) your pants

ANSWER: A

A wattmeter can be used to measure:

A) True power

B) Apparent power

C) Reactive power 

D) Quadrature power

ANSWER: A

Measuring current and voltage in an AC circuit, will enable the calculation of:

A) apparent power

B) quadrature power

C) input power 

D) true power

ANSWER: A

When using a wattmeter to measure power in a 3 phase star connected system, the voltage coil is connected in:

A) parallel with the load

B) series with the load

C) series with the neutral

D) series with the supply

ANSWER: A


Last modified: Monday, 31 May 2021, 9:07 PM