Electrical Measurement And Relay Protection For Distribution Systems
Jun 08, 2018

Transformer is a kind of static electrical equipment used to convert AC voltage and current to transmit AC energy. It is based on the principle of electromagnetic induction to achieve power transfer. Transformers can be divided into power transformers, test transformers, instrument transformers, and special-purpose transformers for their use: power transformers are necessary equipment for power transmission and distribution, and distribution of power users; test transformers provide withstand voltage (boost) for electrical equipment. Test equipment; Instrument transformers are used for electrical measurement and relay protection of power distribution systems (PT, CT); transformers for special applications include furnace transformers for electric smelting, welding transformers, rectifier transformers for electrolysis, and small-scale regulator transformers.

A power transformer is a stationary electrical device, and is a device for changing an AC voltage (current) of a certain value to another voltage or a voltage (current) of the same frequency. When the primary winding is connected to alternating current, alternating magnetic fluxes are generated. The alternating magnetic flux passes through the iron core and induces alternating current electromotive force in the secondary winding. The magnitude of the secondary induced electromotive force is related to the number of turns of a secondary winding, that is, the voltage magnitude is proportional to the number of turns. The main role is to transmit electrical energy, so rated capacity is its main parameter. The rated capacity is a conventional value of the performance power, which is characterized by the size of the transmitted power, expressed in kVA or MVA. When a rated voltage is applied to the transformer, the rated current that does not exceed the temperature rise limit under the specified conditions is determined. The more energy-efficient power transformer is an amorphous alloy core distribution transformer. Its biggest advantage is that the no-load loss value is extremely low. Ultimately, whether or not the no-load loss value is ensured is a central issue to be considered throughout the design process. When the product structure is arranged, in addition to considering that the amorphous alloy core itself is not affected by the external force, the characteristic parameters of the amorphous alloy must be accurately and reasonably selected during calculation.

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