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Step-up, Step-down, and Isolation Transformers
34 questions By Tony R. Kuphaldt
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Question 4 of 34
Predict how all component voltages and currents in this circuit will be affected as a result of the following faults. Consider each fault independently (i.e. one at a time, no multiple faults):
- Transformer T1 primary winding fails open:
- Transformer T1 primary winding fails shorted:
- Transformer T1 secondary winding fails open:
- Load fails shorted:
For each of these conditions, explain why the resulting effects will occur.
Reveal answer- Transformer T1 primary winding fails open: No current through any component, no voltage across any secondary-side component.
- Transformer T1 primary winding fails shorted: Large current through fuse (which will cause it to blow), little current through secondary winding or load, little voltage across secondary winding or load.
- Transformer T1 secondary winding fails open: No current through any secondary-side component, no voltage across any secondary-winding component, little current through primary winding.
- Load fails shorted: Large current through fuse (which will cause it to blow), large current through secondary winding and load, little voltage across secondary winding or load.
Notes:The purpose of this question is to approach the domain of circuit troubleshooting from a perspective of knowing what the fault is, rather than only knowing what the symptoms are. Although this is not necessarily a realistic perspective, it helps students build the foundational knowledge necessary to diagnose a faulted circuit from empirical data. Questions such as this should be followed (eventually) by other questions asking students to identify likely faults based on measurements.
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Question 5 of 34
Suppose 1200 turns of copper wire are wrapped around one portion of an iron hoop, and 3000 turns of wire are wrapped around another portion of that same hoop. If the 1200-turn coil is energized with 15 volts AC (RMS), how much voltage will appear between the ends of the 3000-turn coil?
Reveal answer37.5 volts AC, RMS.
Notes:Transformer winding calculations are simply an exercise in mathematical ratios. If your students are not strong in their ratio skills, this question provides an application to sharpen them!
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Question 6 of 34
Calculate the voltage output by the secondary winding of a transformer if the primary voltage is 230 volts, the secondary winding has 290 turns, and the primary winding has 1120 turns.
Vsecondary =
Reveal answerVsecondary = 59.6 volts
Notes:Transformer winding calculations are simply an exercise in mathematical ratios. If your students are not strong in their ratio skills, this question provides an application to sharpen them!
Creative and interesting excercises.