MAXScanner calculator widget

Transformer Efficiency Calculator — Load, Core & Copper Losses

Editable live calculator

Change any input — the result updates immediately

No hidden assumptions. Inputs, units and the working stay visible so you can check the calculation.

Transformer rating (kVA) Nameplate apparent-power rating.Present load (% of rated kVA) Operating apparent-load fraction; values above 100% may represent overload and should not be treated as acceptable operation.Load power factor Enter 0–1.Core / no-load loss (W) Use reliable no-load test or manufacturer data.Full-load copper / load loss (W) Use full-load loss data at the applicable reference condition.

Calculated result

96.67% efficiency

Output power: 67.5 kW

Copper loss at 75% load: 1.125 kW

Core loss: 1.2 kW

Total loss: 2.325 kW

Input power: 69.825 kW

Calculated maximum-efficiency point: 77.46% rated load (69.71 kW at entered PF), η ≈ 96.672%.

Scenario comparison — 25% load: 94.439% η, 1.325 kW loss | 50% load: 96.36% η, 1.7 kW loss | 75% load: 96.67% η, 2.325 kW loss | 100% load: 96.567% η, 3.2 kW loss

Model boundary: core/no-load loss is treated as constant at rated voltage/frequency and load loss scales with current squared. Use test-certificate/manufacturer loss data for engineering decisions.

Show the working

1. Load fraction x = 75 ÷ 100 = 0.75.
2. Output = 100 kVA × 0.75 × PF 0.9 = 67.5 kW.
3. Copper loss = 2 kW × 0.75² = 1.125 kW.
4. η = 67.5 ÷ (67.5 + 1.2 + 1.125) × 100 = 96.6702%.
5. xₘₐₓ = √(1,200 ÷ 2,000) = 0.7746 (77.46%).

More actions

Shared links reopen these inputs. Recent and saved calculations stay in this browser unless you clear site data.