As an expert in the field of electrical engineering, I can provide a comprehensive explanation for why AC (alternating current) is more preferred over DC (direct current) in various applications, particularly in power transmission and distribution systems.

Step 1: English Explanation

### Introduction

Electricity is the backbone of modern society, powering everything from household appliances to industrial machinery. The choice between AC and DC is a fundamental decision in electrical engineering, with AC being the dominant choice for most applications. Let's delve into the reasons behind this preference.

### Advantages of AC Over DC


1. Transmission Efficiency
- AC can be easily transformed to higher or lower voltages using transformers. This is crucial for long-distance transmission, as high voltages reduce the current and thus the energy lost as heat, known as I²R losses.


2. Generation and Conversion
- Most power generation sources, such as hydroelectric, thermal, and even some types of renewable energy systems, naturally produce AC. This means that using AC from the outset is more straightforward and requires no conversion.


3. Transformers
- The ability to use transformers to step up and step down voltages is a significant advantage of AC systems. Transformers are more efficient and cost-effective for AC than for DC, which is particularly important for the grid.


4. Safety and Infrastructure
- AC systems have been in place for over a century, and the infrastructure, safety protocols, and understanding of AC are well-established. This historical precedence has led to a robust and reliable AC grid.


5. Cost of Equipment
- The cost of generating, transmitting, and distributing AC is generally lower than that of DC. AC equipment, such as circuit breakers and transformers, is more affordable and widely available.


6. Load Variations
- AC systems can handle varying loads more effectively than DC systems. This is important for meeting the fluctuating demands of consumers throughout the day.

7.
Regulation and Control
- AC systems are easier to regulate and control. For instance, AC motors can be started, stopped, and reversed with relative ease, which is not as straightforward with DC motors.

8.
Safety in Use
- AC has a self-limiting characteristic in that its current naturally diminishes over distance due to its sinusoidal waveform, making it somewhat safer to use in certain applications.

### Disadvantages of DC


1. Transmission Limitations
- DC transmission requires more complex and expensive equipment, such as converters for stepping up and down voltages, which are less efficient than transformers.


2. Generation Conversion
- If power is generated as DC, it must be converted to AC for most uses, adding a step that can reduce efficiency and increase costs.


3. Infrastructure Costs
- Building a new DC infrastructure from scratch is expensive and time-consuming, especially when compared to the existing AC infrastructure.

### Conclusion

While DC has its uses, particularly in low-voltage applications like electronics and batteries, AC remains the preferred choice for power transmission and distribution due to its efficiency, cost-effectiveness, and the established infrastructure that supports it. The ability to transform voltages easily and the compatibility with most power generation methods make AC the more practical choice for large-scale electrical systems.

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It is easy to maintain and change the voltage of AC electricity for transmission and distribution. Plant cost for AC transmission (circuit breakers, transformers etc.) is much lower than the equivalent DC transmission. From power stations, AC is produced so it is better to use AC than DC instead of converting it.read more >>