EE 103 EXAM

In a balanced 3-phase system y-connected circuit the lline voltages are equal to

• to the phase voltage

• to 1.414 times the phase voltage

• and so are the line currents

• three times the phase voltage

In the two wattmeter method of measuring power taken by a balanced 3-phase load, if the load power factor is 0.50, one of the wattmeters will read

• one half of total power

• 0.866 of total power

• 0.707 of total power

• zero

 In a 3-phase, 3 wire system, the sum of the line currents is equal to

• 3 x phase current

•  sq. of 3 x phase current

• the current in the neutral conductor

• zero

Which of the following is not a method in measuring power taken by a balanced 3-phase load using ony one wattmeter?

• potential load shifting method

• Artificial meutral method

• T-method

• Potential transformer method

Using the artificial neutral method, if the wattmeter reads 600 watts then the total power taken is equal to __ watts

• 600

• 1200

• 1800

• 900

The T-method is used in measuring the total power taken by a balanced 3-phase load. If the total power is 1200 watts. The wattmeter deflection is __ watts

• 1200

• 400

• 800

• 600

What is the minimum number of wattmeters required for measuring power of a balanced 3-phase load?

• one

• two

• three

• four

What is the minimum number of wattmeters required in measuring power in an unbalanced 3-phase load?

• one

• two

• three

• four

In the two watt-meter with the load balanced the readings of the wattmeters will be identical if the power factor is

• 0.50

• 0.707

• unity

• 0.866

In a delta connection pf a balanced 3-phase load the line currents is

• sq. of 2 x phase current

• vector sum of the phase currents

• equal to the line current

• sq. of 3 x phase current