Basic Transformer

Course Description

This combined lecture and laboratory course introduces students to the theory, construction, operation, and application of electrical transformers within the Energy Power Technology field. Students examine the principles of electromagnetic induction as they apply to transformer design, explore single-phase and three-phase transformer configurations, perform voltage and current calculations using the turns ratio, and develop hands-on skills in transformer testing, troubleshooting, and maintenance. The course is designed to prepare students for entry-level positions in electrical power generation, distribution, and industrial maintenance.

This is a combined lecture/laboratory course (lab indicator: C), meaning lecture and laboratory components meet together in the same location and time period. The course is part of the Engineering Technologies > Energy Power Technology taxonomy in Florida's Statewide Course Numbering System (SCNS).

Learning Outcomes

Required Outcomes

Upon successful completion of this course, students will be able to:

• Explain the principles of electromagnetic induction and how they govern transformer operation.
• Identify and describe the major components of a transformer, including the core, primary winding, secondary winding, and insulation system.
• Apply the turns ratio to calculate primary and secondary voltages, currents, and impedances in ideal transformers.
• Distinguish between step-up and step-down transformer configurations and identify appropriate applications for each.
• Analyze transformer power losses, including copper (I²R) losses and core losses (hysteresis and eddy current), and describe methods to minimize them.
• Perform standard transformer tests, including turns-ratio tests, polarity tests, and insulation resistance tests, using industry-standard instruments.
• Read and interpret transformer nameplate data, including kVA rating, voltage ratings, frequency, and impedance percentage.
• Demonstrate safe work practices when working with energized and de-energized transformer equipment in accordance with OSHA and NFPA 70E standards.

Optional Outcomes

Depending on instructor emphasis and available laboratory equipment, students may also be able to:

• Connect and test three-phase transformer banks in delta-delta, wye-wye, delta-wye, and wye-delta configurations.
• Explain autotransformer construction and operation and compare it to isolation transformer designs.
• Describe instrument transformers (current transformers and potential transformers) and their roles in metering and protection systems.
• Identify and apply basic transformer protection schemes, including overcurrent protection and differential relays.
• Explain transformer cooling methods (dry-type, oil-immersed, ONAN, ONAF) and their maintenance requirements.
• Use software or simulation tools to model transformer circuit behavior and verify calculated results.

Major Topics

Required Topics

1. Review of Magnetism and Electromagnetic Induction
   • Magnetic fields and flux density
   • Faraday's Law and Lenz's Law
   • Mutual inductance
2. Transformer Construction and Types
   • Core types: shell, core, and toroidal
   • Winding materials and insulation
   • Dry-type vs. liquid-filled transformers
   • Transformer nameplate data interpretation
3. Transformer Theory — Ideal Transformer
   • Turns ratio relationships (voltage, current, impedance)
   • Power relationships in ideal transformers
   • Voltage regulation concept
4. Transformer Losses and Efficiency
   • Copper losses (I²R)
   • Core losses: hysteresis and eddy currents
   • Efficiency calculations
5. Single-Phase Transformer Applications
   • Step-up and step-down configurations
   • Polarity markings (additive and subtractive)
   • Series and parallel winding connections
6. Transformer Testing and Troubleshooting
   • Turns-ratio test (TTR)
   • Insulation resistance (Megger) testing
   • Polarity testing
   • Load and no-load tests
   • Common faults: opens, shorts, grounds
7. Transformer Safety
   • Lockout/tagout (LOTO) procedures
   • Arc flash and shock hazard awareness (NFPA 70E)
   • Personal protective equipment (PPE) selection

Optional Topics

1. Three-Phase Transformer Connections
   • Delta-delta, wye-wye, delta-wye, wye-delta configurations
   • Voltage and current relationships per connection type
   • Phasing and paralleling three-phase transformers
2. Autotransformers
   • Construction and operating principles
   • Comparison to isolation transformers
   • Common applications (variable autotransformers/Variacs)
3. Instrument Transformers
   • Current transformers (CTs) — operation and burden ratings
   • Potential/voltage transformers (PTs/VTs)
   • Use in metering, protection, and relaying
4. Transformer Protection and Cooling
   • Overcurrent and differential protection
   • Cooling classifications: AN, ONAN, ONAF, OFAF
   • Oil sampling and dielectric testing
5. Special-Purpose Transformers
   • Control transformers
   • Isolation transformers
   • Buck-boost transformers

Resources & Tools

• Test Equipment: Turns-ratio tester (TTR), digital multimeters (DMM), clamp-on ammeters, megohmmeter (Megger), oscilloscope
• Laboratory Hardware: Single-phase and three-phase transformer trainers, variable autotransformers (Variacs), load banks
• Reference Standards: NFPA 70 (National Electrical Code), NFPA 70E (Electrical Safety in the Workplace), IEEE C57 transformer standards series
• Textbooks: Transformers and Motors (Delmar/Cengage series), Electrical Wiring Industrial (Delmar), manufacturer technical manuals (Eaton, ABB, Square D)
• Software/Simulation: NI Multisim, MATLAB/Simulink (optional), manufacturer relay coordination tools
• Online Resources: Florida Statewide Course Numbering System (flscns.fldoe.org), OSHA electrical safety resources, IEEE Xplore

Career Pathways

Successful completion of ETP2120C supports entry into or advancement within the following career areas:

• Electric Utility Technician — substation maintenance, distribution transformer testing and installation
• Industrial Electrician / Maintenance Electrician — plant transformer maintenance, motor control centers
• Power Systems Technician — generation facility support, switchgear and transformer operation
• Instrumentation and Controls Technician — instrument transformer calibration and relay testing
• Electrical Contractor / Journeyman Electrician — commercial and industrial wiring involving transformers

This course may count toward the Associate in Science (A.S.) in Energy Power Technology or related electrical/electronics technology degree programs at Florida state colleges. Credits may also apply toward industry apprenticeship hours.

Special Information

Certification Preparation

The skills and knowledge developed in ETP2120C provide foundational support for the following industry credentials:

• NCCER Electrical — Transformers Module (National Center for Construction Education and Research): This course aligns with NCCER Electrical Level 3 transformer content, which is widely recognized by Florida contractors and utilities.
• OSHA 10 / OSHA 30 — Electrical Safety: Safe work practice content directly supports OSHA electrical safety certification preparation.
• NFPA 70E — Electrical Safety in the Workplace: Arc flash and PPE content aligns with NFPA 70E awareness-level training objectives.
• ETA International — Electronics Technician (ET): Transformer theory supports broader Electronics Technician certification exams offered by ETA International.

Note: The "C" lab indicator means this course combines lecture and hands-on laboratory work in a single meeting, providing integrated theory-to-practice learning essential for technical workforce preparation in Florida's energy sector.