Transformer Losses
A transformer is not 100% efficient because some energy is always lost during operation. These losses mainly appear as heat.
What Are Transformer Losses?
Transformer losses are the difference between input power and output power.
Input Power = Output Power + Losses
Main Types of Losses
1. Copper Loss (Winding Loss)
- Caused by resistance of the windings
- Depends on load current
- Follows IĀ²R rule
Copper Loss = IĀ²R
2. Core (Iron) Loss
Occurs in the magnetic core and is constant regardless of load.
a) Hysteresis Loss
- Due to repeated magnetization of the core
- Depends on frequency and core material
b) Eddy Current Loss
- Circulating currents induced in the core
- Produces heat inside the core
3. Stray Loss
- Leakage magnetic flux
- Induced currents in nearby metal parts
4. Dielectric Loss
- Occurs in insulation material
- More noticeable at high voltages
Summary of Losses
| Loss Type | Depends On | Load Dependent? |
|---|---|---|
| Copper Loss | Current | Yes |
| Core Loss | Voltage & Frequency | No |
| Stray Loss | Leakage Flux | Partly |
| Dielectric Loss | Insulation | No |
Power Loss Relationship
::contentReference[oaicite:0]{index=0}Losses reduce the usable output power and generate heat inside the transformer.
Example
- Input Power = 100W
- Output Power = 90W
Loss = 100W ā 90W = 10W
Effects of Losses
- Heat generation
- Reduced efficiency
- Voltage drop
- Reduced lifespan
How to Reduce Losses
- Use high-quality copper windings
- Use laminated or ferrite cores
- Reduce core thickness (laminations)
- Use proper insulation materials
- Ensure good cooling (air or oil)
Important Notes
- Copper loss increases with load
- Core loss is constant
- Total loss = Copper + Core + Others
- Losses determine efficiency and regulation