Short and Medium Transmission Lines

The purpose of this lab was to examine the characteristics of a short transmission line by looking at a simple circuit model of a short line, and to examine the characteristics of a medium transmission line by looking at a simple circuit model of a medium line. In the first step, we placed a 300 Q resistor in parallel with a 300 Ј1 inductor for the load, set the transmission line impedance to 60 Q, and set Vs = 200 V. Next we removed the load and found the no load measurements. For the next step, we reconnected the load and inserted the phase angle meter to measure the angle of the sending end voltage with respect to the receiving end voltage. For step five, we used the same load, but this time we set the impedance of the transmission line to 120 Q and added a shunt capacitance of 300 Q. Next, we removed the load to find the no load measurements. Then, we reconnected the load and inserted the phase angle meter to find the same values as before. We then removed the phase angle meter and inserted the watt/VARmeter to find the complex power.

Quantity Value Units

P3Φ 40 Watts

Q3Φ 250 VAR

The real power creates torque while the reactive power induces a magnetic field. The power factor is cos (80.91˚) =0.158.

CONCLUSIONS

The 3Φ power system is a complicated network of devices which requires understanding of concepts in the three phase voltages and currents, real and reactive power, and phase sequences. This power system can be used to run a variety of loads which can be connected in two ways, wye and delta.

Most of results found in this lab were exactly as expected. But in part six and seven of the three-phase complex power did differ slightly. If the formulas are examined that are used to find the complex power, it is given that the measured result is a combination of each. Which means you can use one formula to find the real power and the other for the reactive power. The measure value is also 1-2 units smaller than the calculated results which can be explained my miscellaneous losses

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