Trace transformer roles in high-voltage electricity transmission
Follow generation, step-up transmission and later step-down supply through a labelled conceptual network.
Section P4.5.6 · The transformer
Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.
Before you begin
- Use step-up/down terms.
- Distinguish voltage from energy.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Why should input/output roles be assigned separately at each stage?
What you will learn
- Follow generation, step-up transmission and later step-down supply through a labelled conceptual network.
- Explain step-up and step-down transmission roles with local winding labels and a conserved transfer account.
Follow the voltage stages
A high-voltage transmission system can use a step-up transformer near generation to raise the a.c. voltage for long-distance transfer. Step-down transformers later reduce voltage for distribution and suitable consumer supply. Identify input/output roles separately at each transformer; the network is not one winding pair stretching from generator to every home.
The long-distance high-voltage stage helps reduce current for the same transferred power. The later lower-voltage stages suit the connected distribution and user equipment. Voltage values vary by real system; the values in this lesson are supplied examples, not national wiring standards.
Keep the transfer boundary explicit
Electrical energy is transferred through connected sources, transformers, cables and loads. A step-up stage does not create extra energy merely because voltage is larger. Real transformers and cables have losses and operating limits.
A network diagram is a conceptual account of transformer use, not a safe procedure for accessing transmission equipment or household wiring. Keep the generation-to-load sequence and each transformer’s voltage change clear before making power or loss calculations.
Sources for this lesson
Pause and explain
A stage changes 200 kV to 10 kV. What is its role?
Worked example
A supplied conceptual system goes from 20 kV generation to 200 kV transmission, then to 10 kV distribution. Classify the two transformer stages.
Show the worked solution
- 20 kV to 200 kV increases voltage.
- 200 kV to 10 kV decreases voltage.
- The stages are step-up then step-down.
Answer Step-up, then step-down.
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Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Classify 20 kV → 200 kV → 10 kV transformer changes.
Give me a hint
Compare output with input at each arrow.
Compare my reasoning
- The first increases voltage tenfold.
- The second reduces voltage.
- The roles are step-up then step-down.
Step-up then step-down.
Look for these in your work
- Identify both stages.
- Keep the network order.
Explain why the last conceptual transformer reduces voltage before specified user equipment.
Give me a hint
Connect voltage stage to the intended equipment supply.
Compare my reasoning
- Long-distance transmission uses a high-voltage stage.
- The connected later equipment needs its specified supply conditions.
- A step-down stage provides the lower-voltage model output.
To provide the specified lower-voltage supply stage.
Look for these in your work
- Distinguish transmission and use.
- Retain equipment-specific requirements.
A report calls the entire network one transformer and says its step-up stage multiplies energy. Correct it.
Give me a hint
Separate connected stages from winding roles and energy.
Compare my reasoning
- The network contains multiple source, cable, transformer and load stages.
- Each transformer has its own primary and secondary.
- Voltage increase does not create an energy input.
Multiple connected stages transfer energy; a step-up transformer does not create it.
Look for these in your work
- Correct the topology.
- Correct the energy claim.
Common mistakes
- Classify each stage separately.
- Example voltages are not wiring standards.
- Higher voltage does not create energy.
What can you explain now?
Where is a step-up transformer used in this conceptual transmission sequence?
Compare with the explanation
Before the long-distance high-voltage stage
The generation-side step-up raises voltage for the long-distance transmission stage.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Explain step-up and step-down transmission roles with local winding labels and a conserved transfer account.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.