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AC and DC—what do they mean? These electrical terms are often thrown around when discussing power sources, electronics, appliances, outages, etc. But what do they actually refer to, and which use cases are better suited for AC vs DC power?
Explore both alternating current (AC) and direct currents (DC), their pros and cons, and the most popular applications for both waveforms.
Alternating Current (AC)
Alternating current, or AC power, is an electrical current that flows forwards and backwards, periodically changing its direction. AC typically operates at a 50 or 60 Hertz (Hz) frequency, depending on the geographic area, and 13 amps per socket.
AC is the standard home and business electric current because it can easily be transmitted over long distances, and most appliances and electronic systems require it to run. AC was first tested using a Dynamo Electric Generator and Michael Faraday’s principles in 1832. Its popularity remains today as the most preferred electric waveform.
To identify an alternating current, you’ll see a sine waveform that looks like a curved line. The curved lines denote the electric cycles measured per second, with the measurement read in Hz.
Advantages and Disadvantages of AC Power
Alternating current is so commonly used because it provides distinct advantages and only a few drawbacks.
Advantages:
- Reduced power loss over long distances. Because AC voltage can be decreased or increased using a transformer, there’s minimal energy loss in power transmission over extended distances.
- Lower power loss than DC. It suffers less power loss than DC in high-voltage, long-distance transmission.
- Easy to power AC appliances. AC electricity is efficiently distributed and readily available, making it easy to power home electric appliances.
- Greater efficiency. Systems that rely on AC can use the differences in its power phases to share loads and use the electricity more efficiently.
Disadvantages:
- Higher risk. A higher risk is involved because the alternating current has a higher peak voltage.
- Distortion. AC sine waves can become distorted by capacitive and inductive loads.
- Installation safety. Installing AC sources requires more safety precautions because there’s more risk of electric shock.
Applications
Countless devices and systems rely on AC waveforms to function. Here are some of the most common use cases in the UK.
- Power distribution: The grid uses alternating current to distribute energy over long distances with minimal loss of efficiency.
- Home and office: Wall outlets use AC, making it the standard for homes and businesses. It supports refrigerators, air conditioning systems, washing machines and dryers, computers, televisions, and other items with safe and reliable energy.
- Backup power solutions: Solar generators can provide steady AC power, which you can use to run appliances or electronics. This includes EcoFlow Solar Generators and EcoFlow Portable Power Stations. For example, the EcoFlow DELTA Series Portable Power Stations, such as the EcoFlow DELTA 2 Max or EcoFlow DELTA Pro 3, can be paired with DC-producing solar panels and convert the energy into AC. You can also connect them to AC power sources like a wall outlet to charge up before using their various built-in AC outlets to charge other devices.
- Industrial applications: AC is vital in manufacturing processes like assembly lines or chemical processing because it provides high-level, controlled energy.
- Transportation: Alternating current is the primary energy source for electric trains, buses, cars, and aeroplanes due to its reliability, high efficiency, and reduced maintenance.
Direct Current (DC)
Direct current, or DC power, is another type of current that flows consistently in one direction—forwards. The intensity of the current is steady and doesn’t vary over time, giving it its name. Solar cells, fuel cells, and batteries all produce direct currents, and the primary use of this current is to charge batteries or supply power to electrical devices.
Mobile phone batteries, flat-screen TVs, electric vehicles, and flashlights can all be charged or run by DC. That’s why you see the plus and minus sign on so many batteries—the current only flows from the positive terminal (plus sign) to the negative terminal (minus sign).
Think of your devices that run on a batter and require an AC adaptor or USB cable when plugged into a wall. These all run on direct current.
Advantages and Disadvantages of DC Power
DC power is more advantageous than AC in specific ways but still has its drawbacks.
Advantages:
- Reduced loss of power. Because direct current flows evenly through the wire, there’s less power lost to the ‘skin effect’ in low-power, short-distance applications.
- Better storage. DC has no phase factor like AC, so it can be easily stored.
- Low loss, high power. Direct current systems have low power loss, so the energy transmitted is quite high.
Disadvantages:
- Expensive. Because they require more insulation, DC systems cost more to purchase and install.
- Cannot change voltage. You can’t change DC voltage easily without also losing significant energy.
- Cannot handle long distances. Direct current loses voltage over long distances, so transmitting them over large regions is not economical.
Applications
From electronics to telecom and renewable energy, these are the use cases where direct current is preferred.
- Transportation: DC power keeps the batteries on electric cars, trucks, and buses topped up. Fast-charging DC stations can replenish them quickly, allowing for longer trips and fewer disruptions.
- Telecommunications: The telecom and computing industries are beginning to use DC power more, such as in data centres, mobile phone towers, and servers. This comes as part of a renewed focus on energy efficiency.
- Renewable Energy Systems: Solar and other renewable systems generate DC power initially, which is usually stored in batteries for later use. However, built-in DC-to-AC inverters convert it to AC electricity that the grid, homeowners, or appliances can use.
- Electronics: Smartphones, earbuds, tablets, and other portable devices use direct current to charge their batteries.
What Are the Main Differences Between AC and DC?
Alternating current alternates its direction periodically, as its name suggests. This creates a curved sine waveform. On the other hand, a direct current maintains one direction and a steady flow of energy, demonstrated by a straight line. Take a look at the table below to understand the primary differences between the two.
| Alternating Current (AC) | Direct Current (DC) |
| Can be easily transferred over long distances, such as between cities, with minimal loss of energy | Cannot be transferred long distances, or it loses electric power |
| Rotating magnets create changing electric flow direction | Steady magnetism creates a single-direction flow |
| Current flow changes direction periodically | Flows in one direction consistently |
| Electrons flow both forward and backward | Electrons only move forward |
| Frequency depends on the country, usually 50 or 60 Hz | Zero frequency/no frequency |
Why Is AC and DC Power Necessary?
We rely on both alternating current and direct current in the modern world because each has unique properties that fit different use cases. AC can travel long distances, making it ideal for the electric grid’s infrastructure to power homes and businesses.
However, DC is also vital for sensitive electronics and battery-powered systems. It’s also used in renewable energy systems, so it’s essential in creating a sustainable energy future.
Frequently Asked Questions
The UK uses alternating current (AC) electricity in its main supplies with a frequency of 50 Hz and a voltage of 230 V. Homes and businesses rely on AC power to run appliances and electronic devices because it can be transmitted much better over longer distances.
House electricity typically uses an alternating current (AC) because the energy is sent long distances from the grid throughout the service area. AC electrical currents can be transferred long distances with minimal loss of power. Some home devices, like TVs or other electronics, use DC power but use adaptors to convert AC from the wall into DC.
DC is used in specific applications because it provides a one-directional, steady, and constant flow of electricity. Electric vehicles, computers, TVs, and smartphone batteries all use DC power to ensure a constant voltage level that protects sensitive electronic devices.
Final Thoughts
It’s impossible to say whether AC or DC power is better; it’s neither here nor there. Both electric currents are essential to modern electricity use, from keeping our homes powered to charging up important electronics and EVs.
Understanding these waveforms’ key differences and applications can better help you understand how your energy sources work and their role in solutions like our EcoFlow Solar Generators.