Transformadores Eléctricos Explicados

Summary

This video explains the working principles of transformers, crucial components in modern electrical systems. It covers how transformers adjust voltage and current, their role in energy transmission, and why they only work with alternating current (AC). The video also discusses various types of transformers, including those used in homes, businesses, and entire regions, as well as how they function to reduce energy loss during long-distance transmission. Additionally, the video explores transformer calculations, including voltage and current relationships, and highlights key terms like Volt-Amps (VA) and reactive power.

Takeaways

• 😀 Transformers are essential devices used to transfer electrical energy and change voltage and current. They are found everywhere, from doorbell circuits to large power stations.
• 😀 Transformers only work with alternating current (AC) and not with direct current (DC). This is because the changing magnetic field in AC allows energy transfer, which doesn’t occur with DC.
• 😀 Transformers are classified using volt-amps (VA) or kilovolt-amps (kVA), not watts or kilowatts, since they don’t specify the load connected to them.
• 😀 Small transformers are used in household devices like doorbells and laptop chargers, while large ones are used for powering cities or regions.
• 😀 Transformers work by using two coils of wire around a magnetic iron core. The primary coil is connected to the power source, and the secondary coil is connected to the load.
• 😀 High voltage transmission over long distances reduces energy loss. For example, electricity is transmitted at high voltage (400,000V) and then stepped down to usable levels (120-240V) for homes.
• 😀 In transformers, the primary coil’s high voltage results in a low current, and this reduces energy losses due to the resistance of transmission wires.
• 😀 The power loss in cables depends on both voltage and current. High voltage reduces the current, resulting in minimal energy loss over long distances.
• 😀 Transformers cannot create energy but simply convert it between voltage and current. A step-up transformer increases voltage but reduces current, while a step-down transformer does the opposite.
• 😀 The efficiency of a transformer is impacted by losses such as copper loss (due to wire resistance) and iron loss (due to the magnetic field in the core).
• 😀 Transformers are also used in rectifiers, which convert AC to DC by using diodes and capacitors. This is essential for devices that require DC power, such as electronic circuits.

Q & A

What is the primary function of a transformer?

A transformer is a device used to transfer electrical energy between circuits. It can change the voltage and current in the process, which is essential for efficient energy distribution.

Why do transformers only work with alternating current (AC)?

Transformers only work with alternating current (AC) because the changing magnetic field generated by AC induces a voltage in the secondary coil. With direct current (DC), the magnetic field would remain constant, so no voltage would be induced.

What is the difference between an 'elevating' and a 'reducing' transformer?

An elevating transformer increases the voltage at the secondary coil while reducing the current, and a reducing transformer decreases the voltage at the secondary coil while increasing the current.

How do transformers help reduce energy loss during electricity transmission?

Transformers reduce energy loss by increasing the voltage and lowering the current before transmitting electricity over long distances. Higher voltage reduces the energy lost due to resistance in the transmission cables.

What is the role of the iron core in a transformer?

The iron core in a transformer enhances its efficiency by concentrating and directing the magnetic flux between the primary and secondary coils. This allows for better induction of voltage in the secondary coil.

What causes the buzzing sound in transformers?

The buzzing sound in transformers is caused by the vibration of the iron core due to the alternating current. The current causes tiny expansions and contractions in the iron plates, leading to vibrations.

What is the difference between 'real power' and 'apparent power' in a transformer?

Real power, measured in kilowatts (kW), is the actual usable power that performs work, while apparent power, measured in volt-amperes (VA), is the total power supplied by the transformer, which includes both real power and reactive power (unused energy).

Why is the power rating of transformers given in volt-amperes (VA) instead of kilowatts (kW)?

Transformers are rated in volt-amperes (VA) because they only transfer energy and do not consume it. The real power consumed depends on the load connected to the transformer, which is why VA is used to indicate the transformer's capability.

How do transformers affect the frequency of electricity?

Transformers do not change the frequency of electricity; they only modify the voltage and current. The frequency remains the same as the input frequency, whether it's 50 Hz or 60 Hz.

What is the significance of the turns ratio in a transformer?

The turns ratio, which is the number of turns in the primary coil compared to the secondary coil, determines how the voltage and current will be altered. A higher number of turns in the secondary coil increases the voltage, while a lower number reduces it.