Basic principles and working mechanism of power transformers

The basic principles and working mechanisms of power transformers can be summarized as follows:

1、 Basic principles

A power transformer is an electrical device that operates based on the principle of electromagnetic induction, capable of converting voltage or current between two or more windings at the same frequency. Transformers are mainly composed of iron cores (magnetic cores) and coils (windings), where the iron core is the magnetic circuit part and the coil is the circuit part.

2、 Working mechanism

1. Electromagnetic induction: When an alternating current is introduced into the primary coil, an alternating magnetic flux is generated in the iron core, which passes through both the primary and secondary coils simultaneously. According to the principle of electromagnetic induction, the changing magnetic flux will induce electromotive force in the secondary coil, thereby generating current.

2. Voltage conversion: By changing the turns ratio of the primary and secondary coils, voltage can be increased or decreased. Specifically, if the number of turns of the primary coil is greater than that of the secondary coil, the output voltage will be lower than the input voltage, which is a step-down transformer; On the contrary, if the number of turns of the primary coil is less than that of the secondary coil, the output voltage is higher than the input voltage, which is a step-up transformer. The turns ratio also determines the proportion of voltage conversion.

3. Current transformation and impedance transformation: In an ideal situation, the input power of a transformer is equal to the output power. Therefore, the current in the primary coil is inversely proportional to the current in the secondary coil. In addition, transformers can also serve as impedance transformers, making one side of the impedance appear as a different impedance value on the other side.

4. Energy transmission and loss: Transformers transmit electrical energy from the primary side to the secondary side through electromagnetic coupling. In actual operation, there will be a certain amount of energy loss due to hysteresis and eddy current losses in the iron core, as well as resistance losses in the winding. These losses will lead to an increase in transformer temperature, affecting its operational efficiency and lifespan.

5. Cooling and protection: In order to maintain the normal operating temperature of the transformer, appropriate cooling measures need to be taken, such as natural cooling, forced oil circulation cooling, etc. At the same time, in order to ensure the safe operation of transformers, overload protection, short circuit protection and other protective measures need to be set up to cut off the power supply in a timely manner in case of faults, avoiding damage to equipment or causing safety accidents.

In summary, power transformers achieve voltage, current, and impedance transformation through the principle of electromagnetic induction, and are indispensable and important equipment in the power system.