Frequently Asked Questions from TANO CABLE

1. Different concepts

AC stands for alternating current, which refers to current whose direction and magnitude change periodically over time. Simply put, alternating current changes direction many times in one cycle.

DC stands for direct current, which refers to current whose direction and magnitude remain constant. The current of direct current flows in only one direction, so its voltage is also constant.

2. Different working principles

The working principle of AC is based on Faraday's law of electromagnetic induction. When a coil rotates in a magnetic field, an induced electromotive force is generated in the conductor, thereby generating alternating current. Since the rotational motion is periodic, the direction of the generated current will also change periodically, which is the characteristic of alternating current. In the power grid, the generator generates alternating current through a rotating magnetic field, and changes the voltage through a transformer, and finally transmits it to the user end.

The working principle of DC is relatively simple. When the power supply provides a constant voltage difference, the current will flow from the positive pole of the power supply to the negative pole in a fixed direction. The battery is the most common DC power supply, which generates a constant current through a chemical reaction. Since the DC current does not change direction, it can be directly used to drive various electrical equipment.

3. Different applications

Typical applications of AC:
Home power grid: Most households use AC power. Electrical appliances such as lighting, air conditioning, and refrigerators all rely on AC power.
Industrial production: Many industrial equipment, such as motors and welding machines, are driven by AC power.
Power transmission: AC power is transmitted to distant users through high-voltage transmission lines, and then stepped down by transformers for users to use.

Typical applications of DC power:
Electronic devices: Most portable electronic devices, such as mobile phones, laptops, tablets, etc., use DC power.
Electrical vehicles: Batteries of electric vehicles and electric bicycles provide DC power to drive motors.
Energy storage system: Photovoltaic panels in solar power generation systems generate DC power, which is stored in batteries and then converted to AC power for home use through inverters.

4. Advantages and disadvantages

Advantages of AC:
Easy to transmit: AC power can be easily stepped up and down by transformers, so that power can be effectively transmitted to long distances.
Mature power generation technology: AC power generation technology is relatively mature, with low cost, and suitable for large-scale power generation.
Strong grid compatibility: Most power systems in the world use alternating current, which has wide compatibility.

Disadvantages of AC:

Complexity: Since the frequency and phase of AC need to be precisely controlled, the design and maintenance of the power system are relatively complex.

Energy loss: AC will generate induced current during long-distance transmission, resulting in energy loss.

Advantages of DC:

High stability: The voltage and current of DC are constant, not affected by external electromagnetic interference, and suitable for use in electronic devices.

Convenient energy storage: DC can be directly stored in batteries, which is convenient for mobile and portable devices.

High energy transmission efficiency: DC has higher transmission efficiency under certain specific conditions, such as in high-voltage direct current (HVDC) systems.

Disadvantages of DC:

Difficult conversion: It is relatively difficult to increase and decrease the voltage of DC, and complex power electronic equipment is required.

Limited application: Since the global power grid is mainly based on AC, the applications of DC are relatively limited.

AC stands for an alternating current, which refers to an electric current whose direction changes periodically over time, and the average current in one cycle is zero. Unlike direct current, its direction changes over time ,while direct current does not change periodically. The power generation is typically AC-most generators are based on an alternator which creates an alternating current as the wire stator turns within a magnetic field. AC power transmission is also preferred for high voltage transmission because it is relatively easy to step down the voltages for various applications with transformers.

DC stands for direct current, which refers to an electric current that does not change in magnitude or direction over a certain period of time. DC is a constant current that flows in one direction only and does not alternate. For example, the current provides by dry cell batteries is DC. DC is used in a wide variety of applications, including testing equipment in research units and laboratories, battery charging, automotive applications, manufacturing testing, and solar panels. It is worth mentioning here that the power generated by photovoltaic panels is typical DC, which requires the use of a power inverter to convert it for standard power applications.

 

Feature	Feeder	Transmission Line
Purpose	Distribute power locally	Transmit power over long distances
Voltage Level	Low to medium	High to very high
Length	Shorter	Longer
Location	Urban and rural	Less populated areas

A transmission line is used to carry electricity over long distances. It connects power plants to substations and sometimes substations to substations. Key points about transmission lines include:

• Purpose: Transmit electricity over long distances.
• Voltage Level: High to very high voltage.
• Length: Much longer than feeders.
• Location: Often found in less populated areas.

Types of transmission lines
Transmission lines are also classified based on voltage levels and construction types. Here are the main types:

Type	Description
Overhead Transmission Line	Uses towers and conductors. Most common type.
Underground Transmission Line	Buried under the ground. Used in urban areas.
High Voltage Direct Current (HVDC)	Uses direct current. Efficient for very long distances.

A feeder is a power line that carries electricity from a substation to the distribution transformers. These transformers are usually located near the end-users, such as homes and businesses. Here are some key points about feeders: • Voltage Level: Typically low to medium voltage.
• Length: Usually shorter than transmission lines.
• Location: Found in both urban and rural areas.

Types of Feeders

Feeders come in different types based on their configuration and voltage levels. Here are the main types: 

Type	Description
Radial Feeder	Has a single path for electricity. Simple but less reliable.
Ring Main Feeder	Forms a loop. Offers more reliability.
Parallel Feeder	Uses multiple paths. High reliability and load-sharing.