الفهرس 
arabic summaryOnly 14 pages are availabe for public view
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Abstract
The annual energy losses of a distribution transformer are determined accurately and compared with other methods. The present work considers the effect of winding temperature on the calculation of annual energy losses. The obtained results taking this effect into account are compared with that corresponding to methods which neglect such effect. A computer program is used in performing the calculations.
Core losses in a transformer under no-load as well as under koading conditions are measured and determined by using a new method. This method of measurements has the advantages of low cost, simplicity, and accuracy than other methods. The no-load current is measured using the proposed method, also the harmonic components of this current are determined. The effect of variation of load current on the core losses is presented, analysed, and named stray load loss. Variation of load power factor is studied with core losses, stray load loss and components of no-load current.
The new method suggests a subtraction circuit which gives the no-load current under loading conditiond. Then the sampling techniques are used to find the effective value of the no-load current, its harmonic components and the core losses under loading conditions. The constant applied voltage and the no-load current are both sampled at a rate of 2KHZ.