Transformer Losses Calculator Pro

Two levels: Nameplate/Test mode (fast, decision-grade) and Field measurement mode (when data is incomplete). Uses an interval table to compute P0 (no-load) and Pk (load) losses, annual totals, and decision helpers.

No-load losses occur as soon as the transformer is energized, even at zero load. Load losses vary with load approximately with the square of current (or load factor).

Inputs

0 rows
Transformer / Siteoptional
Currency
Tariff/kWh
PF default0..1
Modeinputs source
Field mode still uses interval table; it mainly changes how you express load inputs and defaults.
Row load inputchoose one
If you select kW load, the tool computes x = kW / (S × PF). If PF is blank on a row, PF default is used.
Rated power SkVA
No-load loss P0kW
Load loss PkkW @ x=1
Emission factorkg/kWh
Temperature correction (Advanced)Pk only
Approximation based on copper resistance vs temperature. Use for field screening; exact correction depends on design.
Pk reference°C
Operating temp°C
Demand charge/kW-month
Period Hours Load PF Energized Status Actions
For each interval: If energized, total loss power is Ptotal = P0 + Pk·x². If de-energized, losses are zero.

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FAQ

What is the difference between P0 and Pk?
P0 (no-load loss) occurs whenever the transformer is energized, even at zero load. Pk is load loss at rated current (x = 1), and it scales approximately with x².
Why does de-energizing matter so much at low load?
At low load, load losses are small (Pk·x²), but P0 remains constant when energized. If safe operationally, de-energizing during long off-hours can save approximately P0 × off-hours.
Is temperature correction accurate?
It is an approximation for field screening. Actual temperature correction depends on transformer design and what components are included in Pk (copper + stray). Use test reports for decision-grade analysis.

Decision-grade transformer loss analysis (annual kWh and cost)

This pro transformer losses calculator separates no-load losses (P0) from load-dependent losses (Pk·x²) and computes annual kWh loss using an interval operating table. It helps energy auditors and plant teams quantify the value of de-energizing during off-hours, right-sizing or replacing underloaded transformers, and operating two units in parallel.