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Questions and Answers
What is the purpose of increasing the field current in steps until the armature current exceeds the rated value by 25%?
What is the purpose of increasing the field current in steps until the armature current exceeds the rated value by 25%?
What is the significance of plotting the open-circuit, short-circuit, and zero-power factor characteristics on the same graph?
What is the significance of plotting the open-circuit, short-circuit, and zero-power factor characteristics on the same graph?
What is the purpose of drawing the Potier-triangle?
What is the purpose of drawing the Potier-triangle?
What is the significance of determining the saturated and unsaturated values of the synchronous reactance at rated voltage?
What is the significance of determining the saturated and unsaturated values of the synchronous reactance at rated voltage?
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What is the purpose of increasing the inductance in steps and recording the corresponding values of field current and armature voltage?
What is the purpose of increasing the inductance in steps and recording the corresponding values of field current and armature voltage?
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What is the significance of converting all measured quantities to per unit values?
What is the significance of converting all measured quantities to per unit values?
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What is the assumption while calculating the unsaturated synchronous reactance?
What is the assumption while calculating the unsaturated synchronous reactance?
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What is the purpose of increasing the field current in steps during the open-circuit test?
What is the purpose of increasing the field current in steps during the open-circuit test?
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What is the unit of unsaturated synchronous reactance Xs(ag) when calculated as Vt/Ia?
What is the unit of unsaturated synchronous reactance Xs(ag) when calculated as Vt/Ia?
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What is the characteristic of the synchronous reactance Xs(sat)?
What is the characteristic of the synchronous reactance Xs(sat)?
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What is the condition for the short-circuit current Ia on the S.C.C curve?
What is the condition for the short-circuit current Ia on the S.C.C curve?
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What is the purpose of the short-circuit test as shown in Fig.2 (b)?
What is the purpose of the short-circuit test as shown in Fig.2 (b)?
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What is the main objective of performing open-circuit, short-circuit, and zero power factor tests on an alternator?
What is the main objective of performing open-circuit, short-circuit, and zero power factor tests on an alternator?
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What is plotted in the open-circuit characteristic curve of an alternator?
What is plotted in the open-circuit characteristic curve of an alternator?
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What is the base value used to plot the short-circuit characteristic curve of an alternator?
What is the base value used to plot the short-circuit characteristic curve of an alternator?
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What is the condition under which the zero power factor characteristic curve of an alternator is obtained?
What is the condition under which the zero power factor characteristic curve of an alternator is obtained?
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Which of the following can be determined from the open-circuit and short-circuit characteristics of an alternator?
Which of the following can be determined from the open-circuit and short-circuit characteristics of an alternator?
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What is the significance of the synchronous speed in the open-circuit, short-circuit, and zero power factor tests on an alternator?
What is the significance of the synchronous speed in the open-circuit, short-circuit, and zero power factor tests on an alternator?
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Study Notes
Experiment Objectives
- To perform open-circuit, short-circuit, and zero power factor tests on an alternator (synchronous generator)
- To determine the various parameters of the alternator from the test results
Experiment Procedure
- Increase field current in steps until armature current exceeds rated value by 25%, recording armature current and field current values at each step
- Connect circuit as shown in Fig.2(c) with armature winding connected to a variable inductance
- Adjust inductance to minimum value and increase field current until armature current reaches recommended value (5A), recording field current and armature voltage values
- Increase inductance value in steps, repeating field current increase and measurement
- Measure resistance of one phase of armature winding using a digital ohmmeter
Result and Conclusion
- Convert measured quantities to per unit values and plot open-circuit, short-circuit, and zero-power factor characteristics on the same graph
- Determine saturated and unsaturated values of synchronous reactance at rated voltage from O.C.C and S.C.C
- Draw the Potier-triangle and estimate armature leakage reactance for two types of synchronous machines
- Comment on curve shapes and values obtained for all parameters
Synchronous Reactance
- Unsaturated synchronous reactance (Xs(ag)) found from air-gap line of O.C.C and S.C.C, neglecting saturation
- Saturated synchronous reactance (Xs(sat)) found from O.C.C and S.C.C, taking into account saturation effects
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Description
This quiz is based on an experiment to study the characteristics of a DC machine. It involves measuring armature current and field current, and adjusting inductance to achieve recommended values. Understand the principles and relationships between these electrical parameters.
