EET 151- Lab 6 (Exercise 16); 3-Phase Calculations
Name: ________________________
Build the circuits below and measure the values indicated:
1) Set the loads to 200Ω // +j300Ω (200Ω Resistor (300 Ω //600 Ω)//300Ω Inductors; Capacitors Open)
*I-Phase Total Calculated=√(IR2+IL2); IR= VPhase/R; IL=VPhase/XL
Expected
Measured
VLine
208V
VPhase
120V
IXL
.4A
IR
.6A
ILine-Total
.72A
M1
M2
M1+M2
PT (W)
216W
EET 151, Lab 6; Page 1 of 3
EET 151- Lab 6 (Exercise 16); 3-Phase Calculations
2) Open the Inductor Modules and set the following Impedance Values: 600Ω // -j200Ω (600Ω Resistors //
200Ω Capacitors; Inductors open) *I-Phase Total Calculated=√(IR2+IC2); IR= VPhase/R; I-XC=VPhase/XC
VLine
VPhase
IXC
IR
ILine-Total
PT (W)
Expected
208V
120V
.6A
.2A
.7A
72W
Measured
M1
M2
M1+M2
3) Set the following Impedance Values: 600Ω // +j 200Ω // -j400Ω (600Ω Resistors, 400 Ω (600/1200)
Capacitors and 200Ω Inductors) *I-Phase-Total Calculated=√(IR2+(IXL-IXC)2); IR= VPhase/R; IXC=VPhase/XC;
IXL=V-Phase/XL;PQ=√(PA-PT) Or PQL-PQC
Measured
Expected
VLine
208V
VPhase
120V
IXL
.6A
IXC
.3A
IR
.2A
ILine-Total
.36A
M1
M2
M1+M2
PT (W)
72W
EET 151, Lab 6; Page 2 of 3
EET 151- Lab 6 (Exercise 16); 3-Phase Calculations
Review Questions
1) A 3-phase resistive load has a phase voltage of 440V and a phase current of 25A. What is the True Power
in this circuit?
2) A 3-phase resistive load is connected in a delta-configuration. The live-voltage applied is 560V, and the
current through each load is 140A. What is the true power in the circuit?
3) A 3-phase motor is connected to a source with a line voltage of 480 V. An amp-clamp indicates a current
flow of 45A in each of the 3 lines. What is the apparent power in the circuit?
4) Two analog wattmeters are connected to the motor in question 3. Both wattmeters show an upscale
reading when connected to read in the forward direction. One wattmeter reads 15K W and the other 16.8K
W. What is the true power in the circuit?
5) What is the power factor of the circuit in question 3 (given the wattage from question 4)?
EET 151, Lab 6; Page 3 of 3