Transformer Efficiency
Efficiency of a transformer tells how effectively it converts input power into output power. No transformer is perfect, so some energy is always lost as heat.
Efficiency Formula
Efficiency is defined as:
Efficiency (ฮท) = (Output Power / Input Power) ร 100%
Since:
Input Power โ Output Power + Losses
Power Relationship
In an ideal transformer:
::contentReference[oaicite:0]{index=0}But in real transformers:
Input Power = Output Power + Losses
Types of Losses
1. Copper Loss
- Caused by resistance of winding wires
- Increases with current (IยฒR loss)
2. Core (Iron) Loss
- Hysteresis loss (magnetic switching)
- Eddy current loss (circulating currents in core)
3. Other Losses
- Leakage flux
- Mechanical vibrations
Typical Efficiency Values
| Transformer Type | Efficiency |
|---|---|
| Small transformers | 80% โ 90% |
| Medium transformers | 90% โ 95% |
| Large transformers | 95% โ 99% |
Example Calculation
Given:
- Input Power = 120W
- Output Power = 108W
Efficiency = (108 / 120) ร 100 Efficiency = 90%
How to Improve Efficiency
- Use low-resistance copper windings
- Use high-quality core materials (silicon steel, ferrite)
- Proper cooling (air or oil)
- Reduce eddy currents using laminated cores
Important Notes
- No transformer is 100% efficient
- Losses increase with load
- Efficiency is highest near rated load
- Heat is the main indicator of losses
Quick Memory Trick
- Efficiency = Output รท Input
- Losses reduce efficiency
- Better design โ Less heat โ Higher efficiency
Applications
- Power distribution
- Audio amplifiers
- SMPS and linear supplies
- Industrial systems