1. Ensure that the power supply (unit 8821-25) switched off. 2. Make the appropriate connections either for virtual or conventional instrumentation shown in figure 3-6. I PRI R E1 E2 E3 Figure 3-6: Effect of Core Saturation on Exiting Current 3. In the virtual instrumentation set the range of ammeters in low mode. 4. Ensure the dial on the power supply is set to zero position. 5. Switch on the power supply unit and using the output voltage dial, take the results after reaching 10% from the indicator. 6. Repeat 5 after increasing another 10% (Use data table on the virtual program to record the results) and continue repeating until reaching 100% (Table 3-1). 7. Switch off supplies. 8. Observe the curve of primary voltage versus exciting current represented by El. 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% E E Table 3-1 E3 1 Exercise 3.2: - Does the exciting current increase more rapidly after the rated voltage is exceeded? Why? - Does the curve illustrate that the transformer core becomes saturated? - Review the measured data to determine how the primary-to-secondary voltage ratio was affected when the transformer core became saturated.