* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Lab 2
Immunity-aware programming wikipedia , lookup
Ground loop (electricity) wikipedia , lookup
Stepper motor wikipedia , lookup
Power factor wikipedia , lookup
War of the currents wikipedia , lookup
Spark-gap transmitter wikipedia , lookup
Electric power system wikipedia , lookup
Electrification wikipedia , lookup
Pulse-width modulation wikipedia , lookup
Mercury-arc valve wikipedia , lookup
Electrical ballast wikipedia , lookup
Ground (electricity) wikipedia , lookup
Variable-frequency drive wikipedia , lookup
Power inverter wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Power engineering wikipedia , lookup
Earthing system wikipedia , lookup
Electrical substation wikipedia , lookup
Power MOSFET wikipedia , lookup
Power electronics wikipedia , lookup
Surge protector wikipedia , lookup
Single-wire earth return wikipedia , lookup
Resonant inductive coupling wikipedia , lookup
Current source wikipedia , lookup
Voltage regulator wikipedia , lookup
Opto-isolator wikipedia , lookup
Stray voltage wikipedia , lookup
Buck converter wikipedia , lookup
History of electric power transmission wikipedia , lookup
Voltage optimisation wikipedia , lookup
Three-phase electric power wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Mains electricity wikipedia , lookup
ECE 385 Lab 2 Measurements on Single-Phase Transformers Due: Oct 4, 2007 Group 27Bravo Authors: David Gitz Scot Shelton Salman B. Measurement of the Transformer Ratio Objective: To measure the transformer ratios in a multi-terminal transformer. Theory: V N o 2 a V N i 1 Procedure: 2. Connect the transformer primary and secondary windings in series, as shown in fig. 5. Make sure the terminal switches are in the up position. The transformer connected in this manner is used as a step-up transformer: the X side (low voltage) will be connected to the source, and become the primary side; the H side (high voltage) will be connected to the load, and become the secondary side. 3. Apply 60 V across the X1-7, and measure, using a hand-held voltmeter, the voltages between H1-5, H2-5, and H4-5. Results: Series Connection: (Actual) Supply: 60.0 Vac H1-5: 120.0 Vac a=2 H2-5: 104.0 Vac a = 104.0/60.0=1.733 H4-5 60.0 Vac a = 1.0 Parallel Connection: (Theoretical) Supply: 60.0 Vac H1-3: 60.0 Vac H4-5: 60.0 Vac Conclusion: Transformers can be used to provide operator-selectable input and output voltages as are required by their application. Questions/Problems: Since the Series connection has an HV output of 120.0, in parallel the 2 outputs should be half as much, i.e. 60.0 Vac each. C. Open-Circuit Test Object: To perform measurements on the transformer under open-circuit (no-load) conditions; to measure the core losses and the excitation current; to use the measurements to characterize the magnetizing branch of the transformer circuit. Theory: It is possible to measure certain parameters of a transformer circuit using the Open-Circuit test. Procedure: 1. Connect the transformer as in fig. 6, with the X side connected to the variable source and the instruments shown in the figure, and the H side terminals connected to a voltmeter. 2. Turn on the power source while the voltage knob is turned to zero. Increase the source voltage to 60 V. Record the voltage Vh across the secondary. 3. Record the power into the primary Px, and the current into the primary Ix. Results: I x 3.0 mA Voc 60.0 V Poc .15W Conclusion: Using the open-circuit test, it is possible to measure the Resistance of the Core and the Reactance of the Core. Questions/Problems: Rc Voc 2 Poc 24.0k I V 2 X m 1 oc oc Voc Poc 2 2 36k D. Short-Circuit Test Object: To perform measurements on the transformer under secondary side short-circuit, to measure the series losses, to use the measurement sot characterize the series impedance of the transformer equivalent circuit. Theory: Using the Short-Circuit test, it is possible to measure other certain parameters of a transformer. Procedure: 1. Connect the transformer in fig. 7, with the H side terminals shorted, and the X side connected to the variable source through the same instruments in the previous procedure. 2. Turn the power source on, while the voltage knob is turned to zero. Slowly turn the voltage knob up to raise the voltage. The current will rise rapidly. Slowly increase the voltage until the primary current Ix is .85 A. This is the rated primary current. Record the current, the power Px, and the primary voltage Vx across X1-7. Results: Vsc 9.00 V I sc .85 A Psc 3W Req Psc 4.15 I sc 2 2 V 2 X eq sc Req 3.12j I sc Rated Current: .428 A Ploss I sc Req 2.86W 2 PFLloss Vsc I sc 7.65W Pout PFLloss 7.65W 100% .7038 Pin PFLloss Poc Ploss 7.65W .36 W 2.86 W Conclusion: By using the Short-Circuit test, it is possible to measure the resistance of the transmission wires and their inductance. Graphs: Req 4.15 Ohms 1 Xeq 3.12 Ohms 2 1 2 2 Z-Load Xm 40.0 kOhms Rc 333.0 Ohms 2 Vsource 1 1 E. Operation Under Load Object: To measure the transformer performance under load; to observe the effects of the load power factor on the transformer voltage regulation. Theory: Operationally parameterizing a transformer system is done while the system is under load. Procedure: 1. Make the connections in fig. 8. Connect the current and watt-meter to the secondary (H side). Connect the resistive and reactive part of one phase of the RLC-100 load across the secondary as showin in the figure. Leave the terminals of the other phases open. 2. Add resistive load. Set switches 1 through 4 of the resistive load to the up position and the remaining switches in the down position. 3. Turn the reactance knob to the full lagging position. 4. Adjust the primary voltage until the secondary voltage is 120 V. Record the primary voltage Vx, the load current Ih, and the load power Ph. 5. Turn the reactance knob to the zero position. Fine-tune the position by observing where the secondary current indication is its minimum. Repeat step 4. Results: Lagging: V X 72.1V I H .38 A PH 32 W VH aVX 142.2V S L VH I H 142.2V .38 A 54.8VAR QL S L P 54.82 32 2 44.49 VA 2 L tan 1 2 QL 54.27 PH pf L cos .584 VR VNL VFL V VH 120.0 142.2 100% oc 100% 100% 15.6% VFL VH 142.2 PL 32W .9709 2 2 PL Req I H Poc 32W 4.15 .38 A .36W Unity: V X 72.3V I H .25 A PH 34 W VH aVX 144.6V S L VH I H 36.15VAR QL S L PH L tan 1 2 2 12.28VA QL 19.86 PH pf L cos .94 VR VNL VFL V VH 120.0 144.6 100% oc 100% 100% 17.% VFL VH 144.6 PL 34W .9821 2 2 PL Req I H Poc 34W 4.15 .25 A .36W Conclusion: This lab has fulfilled its purpose of defining different characteristics of a transformer system and realizing the realistic factors of a non-ideal transformer.