The difference between AC and DC power

Posted by Martin Parker on

Unless you studied electrical or electronic engineering or something similar, or just have an interest in electricity, you may not know the difference between AC and DC electrical supplies. Everyone's heard of the rock band AC/DC right?  

For most people the difference is probably irrelevant. Systems are in place so it is difficult to make a mistake and plug and AC device into a DC supply and vice versa. 

Travel adapters from SublimeWare

When you travel, you most likely take a mixture of items that use AC and DC, so it’s important to choose a travel adapter that can work with both types of devices. 

What does AC and DC mean

Simply, they are acronyms for the type of electrical supply. AC means Alternating Current and DC means Direct Current and it describes the type of power supplied. In simple terms, this means that an AC supply fluctuates from +240V to -240V at the supply frequency. DC supplies remain at a steady level. In the case of USB, it’s +5V. 

The majority of items in your house will be working on AC supplies, plugged in directly to the wall, such as a kettle, fridge or television. Some items, such as laptop computers are plugged into an AC supply, but actually need a DC supply to operate. In these cases a power adapter is used to convert the AC into DC power.

Some small items, such as your mobile phone and tablet require DC supplies, normally from a standard USB connection. For this reason, it’s important to make sure that when you go on a vacation that you take a travel adapter with multiple USB connections.

So let’s look a little more deeply into AC and DC. 

AC power supply

Alternating current power supplies are those provided by your electrical company to your property or office. The supply will be at a set voltage but the direction in which the current flows switches at a periodic rate. 

Around the world there are two basic standards of electrical supply, 100V-127V and 220V-240V, either at an alternating speed of 50 times per second (50Hz) or 60 times per second (60Hz). 

When traveling it’s important to know both your home country’s power supply and that of the country you are visiting, because the two may not be compatible. Read our article on multi-voltage devices to check if you need a power converter as well as a travel adapter. 

DC power supply

DC power supplies are not really an issue. Any item that needs DC power will have been supplied with an adapter that converts AC to DC. 

However, USB connections have become standard across many small devices such as mobile phones and tablets. The USB standard for power is 5VDC, so when you are looking for a travel adapter, make sure you choose one that has multiple USB connections. 

Travel adapter for AC and DC use

The vast majority of travel adapters simply connect one type of plug to a different type of socket. Where the power supplies are the same, this is not an issue, but plugging into the wrong voltage supply could have devastating effects on your equipment. It’s essential to check if your item is compatible and if not either don’t use it or plug it in with a power converter. 

Where the voltage supplies are the same, a travel adapter makes connecting and charging your devices simple. This is particularly true when talking of USB connections. These are not effected by the input voltage and always supply 5V DC.

Make sure you pick a travel adapter that has multiple USB sockets so that you can charge all your devices at once. The SublimeWare Multi-country travel adapter is the perfect partner when traveling abroad, with 4 USB connections and adapters for most major countries.

Travel adapter with multiple USB connectors


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