The difference between DC and AC
- What is the difference between AC and DC ?
Direct Current (DC) and Alternating Current (AC) are two basic forms of current, and they are significantly different in many aspects. TST CABLES summarizes the main differences between the two: - Current direction
Direct Current (DC): The direction of current is fixed, flowing from the positive terminal of the power supply to the negative terminal. Batteries, fuel cells, solar cells, etc. provide direct current.
Alternating current (AC): The direction of the current is periodically reversed, that is, the current flows sometimes in one direction and sometimes in the opposite direction. Powered by the grid, most household appliances use alternating current. - Frequency
Direct Current (DC): There is no concept of frequency because it does not change with time.
Alternating Current (AC): Has a specific frequency that represents the number of times the current reverses per second. The standard frequency of power grids in different countries and regions is different. Mainland China and most parts of Europe are 50Hz, and North America is 60Hz. - Transmission and use
Direct current (DC): When transmitted over long distances, direct current has lower losses in theory because it has no skin effect and proximity effect. However, DC transmission requires special conversion equipment (such as inverters).
Alternating current (AC): It is easy to step up or step down through a transformer, making it convenient for long-distance transmission. This is why AC power is commonly used in power grids. - Power generation method
Direct current (DC): can be generated directly through solar panels, batteries, fuel cells, etc.
Alternating current (AC): Mainly generated by the rotation of generators, such as hydropower stations, thermal power stations, nuclear power plants, etc. - Electronic device compatibility
Direct current (DC): Many electronic devices use direct current internally, and the AC power is converted into the required DC power through a power adapter.
Alternating Current (AC): Can be used directly with most household appliances and industrial equipment. - Security
Direct current (DC): At the same voltage, direct current may cause longer-lasting burns because the resistance of body tissue makes it easier for the current to stay.
Alternating current (AC): The harm of alternating current to the human body is that it can cause muscle contraction, which may cause the person who gets an electric shock to be unable to disconnect from the power source. - Application areas
Direct current (DC): Commonly used in mobile devices, power tools, automotive electronic systems, battery-powered equipment, etc.
Alternating current (AC): widely used in household electricity, industrial production, power transmission and other fields.
The difference between DC cables and AC cables
- The difference between DC cables and AC cables ：AC Cable and DC Cable are two types of cables designed according to different power transmission methods.
There are differences between AC cables and DC cables in terms of design, material selection, structure, etc. This is to adapt to the needs of their different working principles and application scenarios.
There are some key differences between them: - Design principles
AC Cable: Used to transmit alternating current, i.e. the direction of the current changes periodically over time. The frequency of alternating current in mainland China is generally 50 Hertz (Hz).
DC cable: used to transmit direct current, the direction of the current is fixed. Common DC voltages include 12V, 24V, etc., which are mainly used in electronic equipment, electric vehicle charging, solar power generation and other fields. - Structural differences
AC cables: Since AC power generates electromagnetic fields, the design of AC cables needs to consider reducing electromagnetic interference and losses. Shielding is often used to isolate interference, and multi-core stranded conductors may be used to equalize the magnetic field distribution.
DC Cables: DC cables do not require complex shielding designs like AC cables because DC does not produce a changing magnetic field. However, in high-voltage DC transmission, in order to prevent corona discharge and reduce losses, multi-layer insulation structures and special shielding layers are also used. - Material selection
AC cable: In order to improve the anti-aging performance and service life, AC cables often choose materials with good heat resistance and strong corrosion resistance.
DC Cables: Material selection for DC cables may vary, especially in HVDC applications where materials with higher dielectric strength may be used. - Installation and maintenance
AC cable: Pay attention to grounding and shielding effects during installation to reduce interference.
DC cables: DC cables are relatively simple to install, but they still need to follow the appropriate electrical safety standards. - Application scenarios
AC cable: widely used in household power supply, industrial power system, power transmission network, etc.
DC cable: Mainly used in electric vehicle charging systems, solar photovoltaic systems, communication base station power supply, etc. - Electrical Characteristics
AC cable: The effects of capacitive reactance and inductive reactance need to be considered, because alternating current will produce skin effect and proximity effect inside the conductor.
DC cable: DC has no frequency, so there are no problems with capacitive reactance and inductive reactance. The main concerns are resistance and voltage drop. - Heat dissipation characteristics
AC cable: Since the eddy current effect caused by AC current in the conductor will cause increased heat generation, special attention needs to be paid to heat dissipation when designing AC cables.
DC cable: The current in the DC cable does not cause eddy current effects, so its heat dissipation problem is relatively small. - Voltage level
AC cables: AC cables can be designed to different voltage levels as needed, ranging from a few hundred volts to hundreds of thousands of volts for high-voltage transmission systems.
DC cable: Although DC cables can also be designed to high voltage levels, in practical applications, the voltage levels of DC transmission systems are generally much higher than AC transmission systems, such as ±500kV, ±800kV or even higher. - Durability and lifespan
AC cables: AC cables may be affected by factors such as corona discharge during long-term operation, resulting in shortened service life.
DC Cables: DC cables generally have a long service life because they are not affected by the electrical phenomena unique to alternating current. - Economical
AC Cables: For short-distance power transmission, AC cable systems are low-cost and easy to implement.
DC cable: Although DC cable has advantages in long-distance power transmission, the initial investment is high due to the need for special converter stations and other facilities. - Regulations and Standards
AC cables: The design and installation of AC cables must comply with national and regional standards and regulations for power grids.
DC cables: DC cables also need to follow specific standards, especially in the field of high-voltage DC transmission. There are special international standards to guide design and installation. - Anti-interference performance
AC cable: AC cable is susceptible to external electromagnetic interference during the transmission process, so shielding measures need to be taken during design to reduce the impact of interference signals on signals within the cable.
DC cable: Compared with AC cable, DC cable is less affected by electromagnetic interference. Because DC has no frequency change, it reduces the sensitivity to external interference to a certain extent. - Loss characteristics
AC cable: AC cable will have a certain power loss during the transmission process, mainly including resistance loss (I²R loss) and additional losses caused by skin effect and proximity effect.
DC cable: The loss of DC cable mainly comes from the conductor resistance, so under the same conditions, the loss of DC cable is usually lower than that of AC cable. - Construction difficulty
AC cables: When laying AC cables, issues such as the phase relationship between the cables and the capacitive coupling between the cables and the earth need to be considered, and the construction is relatively complicated.
DC cable: There is no need to consider too much phase issues when laying DC cables, and the construction is relatively simple. However, when laying high-voltage DC cables, attention must be paid to preventing insulation breakdown. - Environmental adaptability
AC cable: AC cable is sensitive to changes in ambient temperature. Increased temperature will cause the cable’s current carrying capacity to decrease.
DC cable: DC cable is relatively insensitive to changes in ambient temperature, but it is still necessary to select appropriate insulation materials based on the actual use environment. - Maintenance and inspection
AC cable: AC cables require regular maintenance and inspection during operation, especially the cable joints, to prevent failures caused by poor contact.
DC cables: Although DC cables also require regular maintenance, their maintenance intervals may be longer than AC cables because the failure rate in DC cable systems is generally lower. - Security
AC cables: AC cables may produce arc discharges when faults occur, posing a threat to personal safety.
DC cables: DC cables are generally slightly safer than AC cables, although they are also dangerous at high voltages. - Applicable occasions
AC cable: suitable for urban power grid, industrial power, household power and other occasions.
DC cable: suitable for solar power generation systems, electric vehicle charging piles, submarine cable transmission and other occasions.
The selection of AC cables and DC cables not only depends on technical considerations, but also involves factors such as economic cost, safety, and practical application scenarios. In practical applications, various factors should be considered to select the most suitable cable type. If you are not sure which cable model to choose, please contact TST Cables engineers via email.
In today’s dynamic era, power transmission technology continues to innovate, bringing unprecedented convenience and security to our lives. As an industry-leading power solutions provider, TST CABLES continues to innovate and launch efficient and stable DC cables and AC cables to meet the diverse needs of different companies.
TST CABLES’s DC cables, with their excellent low-loss performance and high transmission efficiency, have become an ideal choice for green energy applications such as new energy vehicle charging and solar photovoltaic power generation. The use of advanced materials and manufacturing processes ensures product durability and reliability, helping customers achieve energy conservation and emission reduction while also promoting the process of sustainable development.
At the same time, TST CABLES’s AC cables have demonstrated extraordinary strength in the field of long-distance power transmission. Through optimized design and strict quality control, TST CABLES’s AC cables can maintain stable performance in various harsh environments, whether it is lighting up thousands of lights on cold winter nights or delivering energy to countless air conditioners in hot summers. Take it in stride. In addition, the AC cables we provide support flexible grid architectures and easily connect to existing power infrastructure, ensuring seamless integration and smooth transition.
If you have customized DC cables, AC cables, low smoke halogen-free cables, high temperature cables, coaxial cables, UL cables, Teflon wires, armored wires, industrial cables, power cables, control cables and other products, you need further technology For support or cable solutions, you can send an email to the professional cable engineers of TST Cable Manufacturer at any time (email: lixiangchao@testeck.com, please indicate your country, your industry, and your needs in the email, we Can provide you with free samples)
