📘 Practical Transformer – Losses & Real Operation
Real transformers are not ideal. They have losses and non-ideal magnetic behavior. Understanding these is crucial for GATE numericals.
🔹 1. Core (Iron) Losses
Occurs in magnetic core due to alternating flux. Two types:- Hysteresis Loss
- Eddy Current Loss
P_core = P_h + P_e
Core loss depends on voltage and frequency.🔹 2. Copper Loss
Due to winding resistance.P_cu = I₁²R₁ + I₂²R₂
Depends on load current.🔹 3. Leakage Flux
Not all flux links both windings. Leakage flux causes:- Leakage reactance
- Voltage drop
🔹 4. Practical Working
When secondary load connected: • Secondary current flows • Demagnetizing effect occurs • Primary draws additional current • Flux remains nearly constant Very important conceptual question.🔹 5. Example – Core vs Copper Loss
Given: Core loss = 500 W Copper loss at full load = 800 W Find total loss at half load. Copper loss ∝ (Load)² At 0.5 load:Copper loss = 800 × (0.5)² = 200 W
Total loss:= 500 + 200 = 700 W
🔹 6. Important Observations
- Core loss constant (approx)
- Copper loss varies with load
- Maximum efficiency when copper loss = core loss
🎯 GATE Important Points
- Know load variation of copper loss
- Core loss depends on voltage
- Leakage reactance important for regulation
- Maximum efficiency condition frequently asked
Real Transformer = Ideal + Losses + Leakage
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