Copper loss is the term often given to heat produced by electrical currents in the conductors of transformer windings, or other electrical devices. Copper losses are an undesirable transfer of energy, as are , which result from in adjacent components. The term is applied regardless of whether the windings are made of copper or another conductor, such as aluminium. Hence the term winding loss is often preferred. The term load loss is used in electricity delivery to describe the portion of the electricity lost between the generator and the consumerNew Zealand Electricity Authority. Guidelines on the calculation and use of loss factors for reconciliation purposes. 26 June 2018. p. 8. that is related to the load power (is proportional to the square thereof), as opposed to the no-load loss.
where I is the current flowing in the conductor and R is the resistance of the conductor. With I in and R in ohms, the calculated power loss is given in .
Joule heating has a coefficient of performance of 1.0, meaning that every 1 watt of electrical power is converted to 1 Joule of heat. Therefore, the energy lost due to copper loss is:
where t is the time in the current is maintained.
With high-frequency currents, the proximity effect and skin effect cause the current to be unevenly distributed across the conductor, increasing its effective resistance, and making loss calculations more difficult.
Litz wire is a type of wire constructed to force the current to be distributed uniformly, thereby reducing Joule heating.
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