Electrical Circuits Applied Scenarios for Engineering Students

Fundamentals of Electrical Circuits

Introduction and Purpose

Electrical engineers must translate theoretical knowledge into practical solutions in real-world workplace environments. This worksheet provides learners with short, applied scenarios or case studies in which they are required to analyze circuits, design solutions, and make safe, competent decisions.

The purpose of this worksheet is to:

  • Develop critical thinking, problem-solving, and analytical skills.
  • Demonstrate the application of Ohm’s Law, Kirchhoff’s Laws, AC/DC principles, and circuit design in workplace contexts.
  • Integrate UK regulations and safety standards (BS 7671, EAWR, PPE regulations) into practical tasks.
  • Strengthen vocational competence by simulating decision-making and troubleshooting scenarios engineers face on the job.

Learners are expected to respond to each scenario with calculations, sketches, circuit diagrams, simulation recommendations, and reflective reasoning.

Scenario 1: Faulty Lighting Circuit in a Commercial Office

Situation:

A commercial office reports that several overhead fluorescent lights are not working. The building operates on 230V AC mains supply, 50Hz. The distribution board shows no tripped breakers.

Tasks:

  1. Using Ohm’s Law, calculate the expected current for a single 36W fluorescent tube.
  2. Apply Kirchhoff’s Laws to determine if the fault could be caused by a broken series connection or an open circuit at the junction.
  3. Draw a simple circuit diagram representing the lighting loop.
  4. Propose a safe testing procedure following EAWR and PPE regulations to locate the fault.
  5. Reflect on how circuit simulation could help verify your proposed solution before working on-site.

Vocational Focus:

  • Practical troubleshooting of live office circuits.
  • Safe isolation and testing procedures.
  • Correct application of theoretical calculations to predict expected measurements.

Scenario 2: Designing a Small Workshop Power Circuit

Situation:

You are asked to design a power supply circuit for a small workshop with 230V AC mains. The circuit must supply:

  • One 1.5 kW motor
  • Two 500W work lights

Tasks:

  1. Calculate the total current draw using Ohm’s Law (I = P/V).
  2. Determine the appropriate MCB rating for circuit protection according to BS 7671.
  3. Draw a schematic diagram of the combined circuit, including the protective devices and switchgear.
  4. Explain how load balancing is considered in AC circuits to prevent overheating.
  5. Reflect on how the design ensures compliance with UK regulations and occupational safety standards.

Vocational Focus:

  • Realistic power calculations for industrial equipment.
  • Correct protective device selection and circuit design.
  • Ensuring compliance with UK wiring regulations in a practical setting.

Scenario 3: DC Battery-Powered Control System

Situation:

A DC-powered conveyor system operates from a 24V battery bank. The control panel requires 3A to operate a solenoid valve.

Tasks:

  1. Use Ohm’s Law to determine the resistor value needed if a 24V supply is applied to a 3A load.
  2. Suggest protective devices suitable for the DC circuit.
  3. Sketch a simple DC control circuit including battery, load, and protection.
  4. Propose a method for testing voltage drops along the circuit before commissioning.
  5. Reflect on potential hazards and safe work practices when handling DC batteries.

Vocational Focus:

  • Practical design and analysis of DC circuits.
  • Battery handling safety and equipment protection.
  • Competency in calculating, designing, and testing workplace control circuits.

Scenario 4: AC Motor Overload in a Workshop

Situation:

A workshop motor rated at 2 kW shows intermittent tripping of the MCB. The supply is 230V AC, 50Hz.

Tasks:

  1. Calculate the expected running current of the motor using P = VI × power factor (assume power factor = 0.8).
  2. Apply Kirchhoff’s Laws to analyze possible wiring or connection issues causing MCB trips.
  3. Recommend protective measures to prevent overloads in line with BS 7671.
  4. Draw a schematic diagram for motor protection including overload relay and MCB.
  5. Reflect on troubleshooting techniques and how simulations could reduce trialand-error testing in the workshop.

Vocational Focus:

  • Analysis of AC motor circuits and overload protection.
  • Selection of protective devices for real-world applications.
  • Critical thinking in troubleshooting operational machinery.

Scenario 5: Fault Detection in a Residential Lighting Circuit

Situation:

During a routine inspection, a residential home lighting circuit shows uneven voltage across lamps. Voltage measured at one lamp is 210V while the other measures 230V.

Tasks:

  1. Use Ohm’s Law and Kirchhoff’s Laws to identify possible causes of voltage drop.
  2. Suggest practical measures to correct the imbalance, such as checking neutral connections or cable sizing.
  3. Propose safe testing methods, isolating circuits before measurement.
  4. Reflect on the role of simulation software in predicting voltage drops in wiring layouts.
  5. Document a step-by-step procedure to safely resolve the issue in line with UK regulations.

Vocational Focus:

  • Practical troubleshooting of residential electrical circuits.
  • Ensuring compliance with safety standards.
  • Connecting theoretical analysis to applied problem-solving in the field.

Scenario 6: Simulation of a Combined AC/DC System

Situation:

You are asked to design and simulate a small workshop system combining AC lighting and DC-powered sensors.

Tasks:

  1. Draw a combined schematic diagram showing AC and DC circuits.
  2. Calculate expected currents for each component using Ohm’s Law.
  3. Use a simulation tool to verify voltage, current, and power ratings before physical installation.
  4. Identify potential fault points and hazards in the system.
  5. Reflect on how simulations reduce risk and improve accuracy in workplace installations.

Vocational Focus:

  • Integration of AC and DC principles in practical applications.
  • Use of simulation to enhance safety and efficiency.
  • Professional practice in design, testing, and fault analysis.

Learner Tasks

Task Overview

You are required to submit a comprehensive engineering analysis worksheet that addresses the six workplace scenarios provided in this document. For each scenario, you must perform the necessary calculations, produce accurate circuit diagrams, and justify your technical decisions against UK safety standards.

Instructions

Calculation & Analysis (Ohm’s & Kirchhoff’s Laws)

  • For Scenarios 1, 3, 4, and 5: Show full mathematical workings to determine current, voltage drops, and power dissipation.
  • Clearly state the formula used and show unit conversions where necessary.
  • Constraint: All calculations must be validated against standard MCB ratings (e.g., 6A, 10A, 16A, 32A) to demonstrate practical awareness.

Schematic Diagrams

  • For Scenarios 2, 3, and 6: Produce a clean, industry-standard schematic diagram.
  • Ensure you use correct symbols for components (e.g., resistors, DC sources, AC sources, fuses, switches) in accordance with BS EN 60617.
    Label all nodes and component values clearly.

Regulatory Compliance & Safety Reflection

  • For every scenario, write a brief “Safety Compliance” note (approx. 50-100 words).
  • Reference specific UK regulations:
    • BS 7671: For cable sizing and protective device selection.
    • EAWR 1989: For safe isolation and working on live systems.
    • COSHH: If relevant (e.g., battery acids in Scenario 3).

Scenario 6 Specific: Simulation Verification

  • For the combined AC/DC system, use a simulation tool (e.g., Multisim or a free online simulator) to model the circuit.
  • Take a screenshot of the simulation showing the “Virtual Multi meter” readings and include this in your worksheet to verify your manual calculations.

Required Evidence: DC and AC circuit analysis worksheets