The Important Difference Between AC and DC Power

The Important Difference Between AC and DC Power

Electricity comes in two different forms: AC power and DC power. AC and DC both accomplish the same goal: providing you with the energy you need for whatever you need - be it turning on a light or powering devices. However, aside from this common mission, AC and DC power could not be more different. Everything from the way they work to where they are practical for use is different - and that’s why it’s important to know the difference between them.

To help you better understand the nature of the energy flowing through your walls and being used in your devices, we’ll explain this important difference and what you need to know about it in this blog.

The History of AC vs. DC Power

AC and DC are not necessarily different types of electricity as both use a flow of electrons to provide the energy you need. But they are a different type of current. In other words, the electricity is the same, but the way it flows through your wires is different - and that makes a huge difference in how each type behaves.

The late 1800s were a remarkable time of scientific advancement and progress and much of the modern technology we depend on today was in its infancy at the time. At that time, electricity, was being pioneered by two gentlemen whose names you’ve probably heard before: Thomas Edison and Nikola Tesla. Thomas Edison was pioneering the advancement and implementation of direct current power (or DC), while a company owned by wealthy entrepreneur George Westinghouse was pushing for the development of AC power. Tesla played a huge part in pioneering the advancement of alternating current, thanks to his patented poly-phase induction AC motor. Tesla famously claimed he could power the entire eastern United States with the energy created just by Niagara Falls.

In the early years of the feud between the two, AC power pretty quickly got a bad rap from a few accidents involving electrocution injuries. Edison and his company fanned the flames by claiming AC current was dangerous and that the hazard was completely ignored by the greedy and callous Westinghouse company which was purely profit-motivated. Edison even went so far as to publicly electrocute animals with alternating current as a demonstration of its danger. However, the popular story that Edison electrocuted a circus elephant named Topsy in one of these displays is in fact a myth—the incident took place roughly a decade before the battle between AC and DC began.

Despite Edison’s constant barrage of attacks on AC technology and several public outcries of poor safety due to electrocution deaths, AC power ultimately won out as the primary source of power due to one important factor: low transmission loss. Under AC power, energy could be sent long distances with minimal loss in voltage or current. A single massive power plant could service customers hundreds of miles away without issue. DC power on the other hand, despite being substantially safer than AC current, lost a ton of energy over even shorter-distance lines. A DC-based grid required power plants every few blocks to service extremely small numbers of customers and that wasn’t practical.

How They Work

So what exactly is the big difference between these two currents? The difference lies in the name. Direct current sends the electrons along a direct path to provide power. They flow in from one lead, through your system and then out through the other. Simple and straightforward. Alternating current on the other hand gets its energy from the electrons in a system rapidly changing direction. Electrons in these systems change direction at a frequency of 60 times every second, creating a measurement known as a “frequency” of 60 hertz.

Common Uses Today

So while AC ultimately won out as the primary form of electricity we think of today, both AC and DC have their uses in modern society. AC current is what is traveling through your walls, in the lines over your head, and even in those gigantic steel structures you may see following the highway. Depending on these structures, the current flowing through these lines can be tens or even hundreds of thousands of volts, as the electricity is being pushed out over an extremely wide area.

However, by the time it gets to your home, the current running through your walls is running at a simple 110 volts. Make no mistake, this level of energy is still dangerous and could cause serious injuries if you’re exposed to it. But it is possible to sustain this kind of electrical exposure and survive. It’s much easier to maintain a consistent voltage at this level. Likewise, most of your large appliances, including your washing machine, electric dryer, dishwasher or refrigerator, all run on alternating current because it’s much safer to supply that kind of energy through an AC power source.

Direct current is found in many more places: on your walls, in your car, and even in your hands! This is because almost all of the devices we have run on direct current power. They receive their power from an alternating current source, but the first thing they do is run the power through a rectifier, which turns the power from AC to DC and then they run it through a series of resistors to drop the voltage.

Everything from the TV on your wall, the remote that controls it to the cell phone in your hands to the electric toothbrush you use more than likely runs on 24, 12, 9, 5, or 3.3 volts of direct-current power. The batteries that power these devices all store and output direct current electricity. Even your car depends on DC voltage—your stereo, air conditioner and even your starter all depend on DC power from your battery to operate.

If you need an electrical repair, call us at Valley Heating, Cooling, Electrical and Solar! Call us at (408) 868-5500 and we’ll get the job done right.