UNIT 27
A delta-connected set of windings has a phase current of 10 A. The line current is _____.
17.32 A
A delta connected set of windings has a phase voltage of 480 V. What is the value of the line voltage?
480V
A wye-connected alternator that has phase voltages of 277 V is feeding two loads. The first load is wye-connected inductors that have 40 W of XL. The second load is delta-connected capacitors that have XC of 60 W. How much is the alternator phase current?
6.93 A
Line voltage and phase voltage are the same in the _____ connection.
delta
In a three-phase connection, the voltage measured between the lines is the _____ voltage.
line
The alternator must supply the _____ for each of the loads.
line current
If a three-phase load is a pure reactive load, then the power calculated has units of _____.
VARS
In a three-phase circuit, the true power (watts) is found by _____.
multiplying apparent power by the power factor
In a three-phase connection, the voltage measured across a single winding is the _____ voltage.
PHASE
A delta connected set of windings has a phase voltage of 100 V. The line voltage is _____.
100V
In calculating power in a three-phase circuit, the phase values of voltage and current are multiplied by _____.
3
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 the _____ connection.
WYE
The horsepower rating of 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
When calculating the power of a pure resistive load, the voltage and current are in phase with each other and the power factor is _____.
1
Often in calculations of values in three-phase systems, the square root of three occurs. The approximate value of this constant is _____.
1.732
Three-phase voltages are _____ out of phase with each other.
120
A delta-connected three-phase alternator is driving a wye-connected resistive load. The alternator output voltage is 480 V. The load resistors are 12 W each. What is the phase current in the alternator?
40 A
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%
The three-phase connection in which three separate inductive loads have been connected together is the _____ connection.
delta
In three-phase power systems, the delivered power _____.
never falls to zero