Electrician Red Seal · Question
An electrician is tasked with identifying the polarity of an unlabelled single-phase transformer. Using a voltmeter and connecting one end of the primary (H1) to an adjacent end of the secondary (X1), they apply a voltage to the primary. If the voltmeter reads the difference between the primary voltage and the secondary voltage when connected in this manner, what type of polarity does the transformer have?
When H1 is connected to X1 and the voltmeter measures the difference between the primary and secondary voltages (i.e., V_H1-H2 - V_X1-X2), the transformer has s
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Question: An electrician is tasked with identifying the polarity of an unlabelled single-phase transformer. Using a voltmeter and connecting one end of the primary (H1) to an adjacent end of the secondary (X1), they apply a voltage to the primary. If the voltmeter reads the difference between the primary voltage and the secondary voltage when connected in this manner, what type of polarity does the transformer have?
Answer options:
- Additive polarity ✅ Subtractive polarity
- Reverse polarity
- Neutral polarity
Correct answer: Subtractive polarity
Explanation: When H1 is connected to X1 and the voltmeter measures the difference between the primary and secondary voltages (i.e., V_H1-H2 - V_X1-X2), the transformer has subtractive polarity. If the voltmeter measured the sum, it would indicate additive polarity.
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