How can the power scale for the circle diagram of an induction motor be determined__________?
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Answer: C. short-circuit test only
Explanation
The short-circuit test provides locked-rotor current and power factor angle measurements. These test values establish the current and power coordinates required for circle diagram plotting. Without short-circuit test data, the correct power scale for the circle diagram cannot be set. Circle diagram construction relies on data gathered from both no-load and short-circuit tests. The short-circuit test determines the diameter and orientation of the active current locus. Power scales are calculated by multiplying voltage, current, and cosine phi scale factors.
Electrical testing engineers use circle diagrams to predict motor performance under varying loads. Standard laboratory reports require short-circuit test measurements to complete performance charts. Modern simulation software calculates these parameters automatically without manual diagram plotting. Option a is incorrect because stator resistance alone is insufficient to set the power scale. Option b is incorrect because no-load tests alone only provide rotational loss and magnetizing data. Option d is incorrect because option c correctly identifies the short-circuit test requirement.
- Subject
- Engineering
- Category
- Electrical Engineering
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- —
- Difficulty
- medium
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