319 lab 6

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319

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Apr 3, 2024

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ECE 319 LAB REPORT 06 SYNCHRONOUS GENERATORS OUMOU TOURE TA: MAHMOUD AL ASHI LAB PARTNERS: RANDY ORELLANA, CHARLES FERRELL PERFORMED : 2-21-24 DUE: 1-28-24 *Every member of the group has materially contributed to the intellectual content of this report

A. Objective In this lab, our goal is to learn more about Open circuit and Short Circuit tests on the Synchronous Generators. Our aim is to precisely measure generator parameters while observing how changes in field current affect terminal voltage across different loads. B. Theory/Introduction Synchronous generators operate at a fixed speed to produce voltage. They rely on prime movers like diesel engines or turbines. The rotor's field coil induced voltage in the stator's armature coils. Key parameters include the relationship between field current and flux, synchronous reactance, and armature resistance. The Open Circuit Characteristic (OCC) shows how armature voltage varies with field excitation when the generator runs at its set speed. It illustrates the relationship between air-gap flux and field excitation. Similarly, the Short Circuit Characteristic (SCC) describes armature and field currents under short circuit conditions. It's a useful measure of the generator's performance. Using the OCC and SCC data, the synchronous reactance at rated voltage is 𝑋 ? = 𝑉 𝑇 / 3 ? 𝑎 where is the armature current, is the short circuit characteristic at the field current and ? 𝑎 ? 𝑎,?? ? ? is the is on the open circuit characteristic on the figure below. 𝑉 ?,?𝑎??? Figure 1: Requirements C. Experiment Setup Fore this experiments, the different materials/equipments used were: - SE2662-3M2: Synchronous Machine operating as a generator. - 1 DC Voltmeter (0-150)

- 1 DC Amp meter (0-1) - 1 AC Voltmeter (0-300) - 1 AC Amp meter (0-2) - SE2662-2N: 0-126 DC Variable Power Supply - SE26626A Servo drive DM - SE2662-8C: Three Phase Resistive Load - SE2662-8P: Three Phase Inductive Load D. Results Generator ratings Table 6.1 Model Number type: SE2662-3M2 Stator winding voltage 220 Stator’s current (A) 1.2/0.70 P(KW) 0.3 Cos ( ) φ 1/0.80 Field Voltage (V) 140 Speed (rpm) 1800m -1 Frequency 600 ? 𝑧 Resistance Measurment Table 6.2 Field Resistance (Ohm) 203.6 Armature Resistance (Ohm) 33.0 Open Cicuit Test Table 6.3

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FIELD CURRENT (A) TERMINAL VOLTAGE (INCREASING FIELD CURRENT) (V) TERMINAL VOLTAGE (DECREASING FIELD CURRENT) (V) 0 9.18 11.4 0.05 14.52 124.3 0.10 222.5 221.2 0.15 297.4 304.5 0.20 365.2 363.3 0.25 402.2 402.7 0.30 432.0 432.3 0.35 453.7 453.5 0.40 464.5 464.5 Short Circuit Test Table 6.4 FIELD CURRENT SHORT CIRCUIT STATOR CURRENT (A) 0 0.23 0.1 0.202 0.2 0.390 0.3 0.599 0.4 0.757 0.5 1.000 Load Test Table 6.5 Resistance (Ohm) THREE-PHASE RESISTIVE LOAD FIELD CURRENT (A) ARMATURE CURRENT (A) 220 0.321 0.573

680 0.146 0.186 220+680 0.129 0.139 1500 0.117 0.87 Inf. 0.103 0.021 Lagging Load Table 6.6 Lagging load with R = 220( and Inductance (H) Ω) THREE-PHASE RESISTIVE LOAD FIELD CURRENT (A) ARMATURE CURRENT (A) 0 (from table 6-5) 0.103 0.021 0.4 0.265 0.362 0.8 0.226 0.243 0.8+.04 0.157 0.103 1.6 0.165 0.121 E. Questions 1. Plot the open circuit characteristics using the data you recorded in Table 6-3. Based on this curve:

Figure 2: FIELD CURRENT vs TERMINAL VOLTAGE (DECREASING FIELD CURRENT) Figure 3: FIELD CURRENT vs TERMINAL VOLTAGE (INCREASING FIELD CURRENT) a. Is this curve linear (straight line) or nonlinear? Why?

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The curve is nonlinear in nature because it describes a hysteresis curve as it saturates b. When the field current is zero the terminal voltage is not zero. Why? The field current is 0 when the terminal voltage is not I believe due to the induced voltage 2. Plot the short circuit characteristics using the data you recorded in Table 6-4. Is this curve linear or nonlinear? Why? Figure 4: Field current vs short circuit Stator current It is linear because the armature current has a linear relationship with the field current therefore it will give us a linear curve. 3. Using equation 6-1, calculate the synchronous reactance of the AC generator for each value of I f in Table 6-4. This will require data from Tables 6-3 and 6-4.

Field Current (A) Terminal Voltage Short Stator Synchronous reactance 0 9.18 0.23 23.04 0.1 222.5 0.202 635.94 0.2 365.2 0.390 540.64 0.3 432.0 0.599 416.39 0.4 464.5 0.757 354.27 0.5 Not found 1.000 Can’t be calculated 4. Using the data from the previous item, plot the armature current, terminal voltage, and the synchronous reactance of the generator vs. the field current. Do this on a single plot, with three different vertical scales - one for current, one for voltage, and one for reactance. Figure5: Field current vs terminal voltage

Figure 6: field voltage vs short stator Figure7: field current vs synchronous reactance

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5. Using Rs, Xs and the different loads in Tables 6-5 and 6-6, and using the OCC, calculate the armature currents and compare them to the experimental results. E A = V Φ + (R+jX S )I A ; I A = 203.6 ; I f = 33.0 6. Plot I a versus I f for the resistive load using the data you recorded in Table 6-5. How should the field current be changed to keep the terminal voltage constant when the load is increasing? Why? Figure8: Resistance vs field current

Figure 9: Resistance vs Armature current 7. Calculate the power factor for each lagging load. Record your values in a table similar to Table 6-7. Table 6-7 Lagging load with R = 220 (Ω) and inductance (H) Power Factor 0.0 0.4 0.8 0.8+0.4 1.6 8. Plot I a versus I f for the lagging load using the data you recorded in Table 6-6. In this case the load resistance is constant (R=220 Ohm). Therefore, the active power is fixed, yet for each inductance value there is a different reactive power demand. How should the field current be changed to keep the voltage constant when the reactive power is increasing? Why?

Figure 9: Field current vs Armature current F. Conclusion In this lab, our objective was to delve into Open Circuit and Short Circuit tests on Synchronous Generators. It was a successful experiment as we did not encounter problems and the values from our results are pretty accurate.

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