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Single Phase Transformer (Experiment) Report.

Extracts from this document...

Introduction

Electrotechnology Coursework Single Phase Transformer (Experiment) Report. Aims. The aims of this experiment are to calculate the turn's ratio of the transformer (in the open and short circuit test), calculate the inductive reactance and rm from the values in the open circuit test. In the short circuit test calculate R1 and X1. Then finally in the load test calculate voltage regulation and the efficiency compare these results to the voltage regulation and efficiency from the equivalent circuit. I will then predict the voltage regulation and efficiency if the load used above had a power factor of 0.8 lagging. Objectives. To determine the approximate equivalent circuit of a single-phase transformer. This will enable me to calculate all the different parameters in the open-and short- circuit tests. Enabling me to predict results for an actual circuit and also compare values between actual and equivalent circuits to see how accurate the estimation or prediction is. Equipment. TecQuipment electrical machines teaching unit NE8010 or NE8013, with the B-phase transformer (EMTU-TT01) on the bench. One feedback electronic wattmeter, one Multi-range moving-iron ammeter and one instrument voltage transformer. Electrical wires where used for the connections between the components of the circuits. Theory and Introduction. A Transformer is a device that transfers electric energy from one alternating-current circuit to one or more other circuits, either increasing (stepping up) or reducing (stepping down) the voltage. Transformers are employed for widely varying purposes; e.g. to reduce the voltage of conventional power circuits to operate low-voltage devices, such as doorbells and toy electric trains, and to raise the voltage from electric generators so that electric power can be transmitted over long distances. Transformers are widely used in power systems for the stepping up the generated voltage from about 20kV to 400kV for efficient transmission and then down again in stages (typically 132kV, 33kV and 11kV) for distribution to industrial consumers and finally to 230V for domestic purposes. ...read more.

Middle

My results show that when I calculate the voltage regulation with the experiment values (actual circuit), the change in the secondary voltage between no-load and full-load is 4.35%. This value is 0.35% greater than the value calculated using the equivalent circuit parameters. So therefore the voltage regulation calculated with the equivalent circuit formula is 4.00%. The Efficiency values are the other way around. For the experiment values used in the efficiency equation, the efficiency value is 94.9%. This value is less than the efficiency value produced when the equivalent circuit parameters are used in the equation. This value is 96.0%. My values are very close to the correct trend from my knowledge. With the circuit not being exactly perfect due to losses, such as power losses due to heating in the wires around the circuit. There are also eddy currents and hysteresis within the core of the transformer. All these losses add up to alter the efficiency of the circuit. With the calculations from the actual circuit the efficiency was calculated and it was lower then the efficiency calculated using the equivalent circuit formula. I can see that the actual circuit formula takes all the losses into account, due to the value of the voltage recorded is used in the formula. With the equivalent circuit parameters being only estimation, this leaves with the opinion of it being less accurate, with also the knowledge of the formula not taking into account the heat losses and power losses in the wire, which is bound to affect the efficiency of the circuit performance. The voltage regulation difference shows that in the equivalent circuit the change from voltage with no load to voltage with a load has a smaller change (smaller percentage) therefore the circuit is more efficient. So with the actual having a larger change (larger percentage) then the efficiency will be less. Areas of Application of Transformers. ...read more.

Conclusion

This method could possibly used for the transfer of electricity across the country via the power lines. Conclusion The experiment went very well for me, the results worked out fine especially when they were compared with the results given from the equivalent circuits, and the voltage regulation values were between 3 and 5 per cent. The circuit was not supplying the most efficient or maximum efficiency, due to the core losses not equalling the copper losses. The load used, which produced a power factor of 0.8 lagging allowed the equivalent circuit method to be tested, it gave normal results, or results that would have predicted before the calculations giving a smaller efficiency and the voltage regulation went up high due to the effect on the transformer. Now I have done this experiment I now realise how important it is to use the equivalent circuit method for prediction and estimation. Using this method will enable large businesses, and especially the electric board to estimate costs of use and to enable them to estimate the amount of voltage required for input and the amount of power output. This will save the businesses a lot of money and a lot of trouble, it they were not able to predict or estimate then they could be a risk of having a too high voltage output and therefore causing injury, and damaging appliances. They could be a problem of having too little voltage and houses been abundant of electrical use. To improve the experiment I would have taken twice as many values for the Open-circuit test, I would have improved the transformer itself, as said in the discussion; we could overlap the layers, or lengthen the coils e.t.c. The connections in the circuit could be improved by using gold connections and better quality copper wire. The accuracy of my results were not the most accurate to get the best results. So therefore the ammeter and the voltmeter readings could have had a more accurate reading, e.g. digital, with the dials being a manual reading would have led to the inaccuracy of our own eyes. ...read more.

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