Delmar's Electricity unit 27
Three phase voltages are -----out of phase with each other
120 degrees
The horsepower rating of a three phase motors and the kilovolt-ampere rating of three phase transformers are about ----- greater than for single phase motors or Transformers with a similar frame size
150 percent
In calculating apparent power (VA) a in a three phase circuit, the phase values of voltage and current are multiplied by------
3
Line voltage in phase voltage are the same in the ----- connection
Delta
Delta connected set of windings has a phase current of 10 A. What is the line current?
I line=Iphase x 1.732 ....17.32A
In a wye connected system, the line voltage is higher than the phase voltage by a factor of ------
The square root of 3. (1. 732)
In a Balanced three-phase system, the conductors need be only about------ the size of conductors for a single phase, two wire system of the same kilovolt-ampere (kVA) rating.
75 percent
In a three phase circuit the true power ( watts) is found by
Multiplying apparent power by the power factor P=sq Root of 3 xE line x I line x PF. Or P=3 x E phase x I phase x PF
In three phase power systems, the delivered power-----
Never falls to Zero
Line current and phase current are the same in the -----configuration
Wye
The three phase connection in which one end of each of the windings are connected together is called a ---connection
Wye