Theory A three Phase circuit is an electrical circuit that delivers 3 cycles within a 60 degree time span. These cycles are 120 degrees apart and can be either unbalanced or balanced with a STAR or DELTA connection. There are many ways to calculate and measure power in a 3 phase circuit but for this laboratory, the Two Waterier Method and Single Three Phase Waterier Method will be used to examine the circuits.
The two waterier method involves connecting 2 power meters to 2 separate lines of the circuit to which the third line becomes neutral.The voltage and current detected by each meter are the voltage and current applied directly to the load. This is the same with the power recorded n each meter and hence the total power dissipated by the load is the sum of both recorded powers. The Single waterier method involves only using 1 power meter and measuring its values across 1 line. With the assumption that all 3 of the lines are balanced, the recorded results will be the results for 1 line. To calculate total power dissipated in the circuit, this power recorded will need to be multiplied by 3.The Balanced Delta Connection showed more accurate results for both single and two waterier methods, however, the single waterier method’s power recording was about 3 times less than the theoretical results. The explanation for this could be that the meter was set to single phase instead of 3 phase.
By forgetting to set it to 3 phase, the recorded power is the power dissipated in 1 line and is not the total power dissipated across the 3 phases. Talk about unbalanced connection.The single waterier method records average power of a three phase circuit to which the total power of the circuit is 3 times this recorded value. The 2 waterier method is a more accurate method as it is ideal that all 3 lines are the same but in real life, the lines are not exactly the same.
Hence, by using 2 power meters, more accurate results can be recorded. The reason why the single and two waterier methods both yield different results is because the two waterier method is measured with respect to the 3rd unmeasured line, making it the preference point.The single waterier method on the other hand measures the power in 1 line then multiplies it by 3 to get the 3 phase power value. If phase ‘C’ of the balanced STAR connection load was disconnected, from my understanding of the invasion power meter, the invasion power reading would be 0 as it is now recording the power of the neutral line and the invasion power reading would be Conclusions Within the limits of experimental error, the theory of the operational amplifier in the two non References Line Jungian EFFIE lecture notes. Clayton G. B. Operational Amplifiers