Joule Heating (I²R Loss)
Heat generated in electrical conductors proportional to current squared times resistance, the dominant source of transformer load loss.
Joule heating (I²R loss) is the fundamental mechanism of copper loss in transformer windings. When current flows through conductor resistance, electrical energy converts to heat at rate P = I²R.
In transformers, Joule heating accounts for the major portion of load loss. The basic I²R component is supplemented by stray eddy current losses in conductors, clamping structures, and tank walls—collectively termed additional losses.
Design optimization: larger conductor cross-section reduces R but increases size and cost. Premium copper with higher conductivity directly reduces losses.
QDTB optimizes winding geometry and uses high-conductivity copper to minimize Joule heating across all oil-immersed and dry-type products. See selection guide for loss evaluation methodology.
Related Products
Related Terms
Copper Loss
Power lost as heat in transformer windings due to electrical resistance, proportional to the square of load current.
Winding Resistance
The DC resistance of transformer windings, measured for loss calculation and connection quality verification.
Eddy Current
Circulating currents induced in conductive materials by changing magnetic fields, causing energy losses in transformers.
Watt Loss
The total real power loss in a transformer in watts, comprising no-load and load loss components.
More Terms Starting with “J”
Junction Box (Electrical)
An enclosure providing accessible entry points for electrical cables, enabling circuit branching and connections within power systems.
Joint Box (Transformer)
A sealed enclosure on transformer tanks providing access to internal winding connections and tap changer linkages.
IEEE C57.12.38
IEEE standard specifying requirements for pad-mounted, self-protected distribution transformers for North American markets.
More in “Electrical Fundamentals”
Apparent Power (kVA)
The total power in an AC circuit combining real (active) and reactive power, measured in kilovolt-amperes (kVA).
Eddy Current
Circulating currents induced in conductive materials by changing magnetic fields, causing energy losses in transformers.
EMF (Electromotive Force)
The voltage generated by electromagnetic induction in a transformer winding, proportional to flux change and turns.
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