Direct Current and Its Applications

Current is known as the flow of electrons or charges through a conducting body. We measure current with a device called an ammeter. Its SI unit is the ampere, denoted by ‘A’. In an alternating current, the motion of electric charge involves a change in direction periodically. In a direct current, the motion of the electric charge is in a single direction without any further change.

Characteristics of Direct Current (DC)

• A direct current is a type of current that flows or moves only in one single direction and does not involve any further changes in its direction, unlike the alternating current. 
• DC was discovered in the 19th century by Thomas Edison. During the 1880s, DC was replaced with the alternating current because it was very difficult to convert DC to lower or high voltages. 
• It was also considered hazardous and was not used in homes. It cannot travel a very long distance, whereas AC is considered safe while transferring to longer distances. 
• The current flowing in products that run on batteries and cells is an example of direct current. By using an inverter, we can convert direct current to alternating current. We can also transform AC into DC by a rectifier.
• As direct current is constant, its symbol is a straight line. 

The Working Principle Behind Direct Current

Unlike alternating current, direct current does not oscillate back and forth. Hence, it provides a constant current. 

There are many ways to generate DC:

1. A commuter is equipped with AC that can produce direct current.
2. A rectifier is also used wherever conversion from AC to DC is required.
3. DC can be generated due to the chemical reactions happening inside the batteries.

The current flow is unidirectional in DC. The voltage and current can change since there is no change in the direction of flow for long.

Differences Between AC and DC

1. In the case of AC, high voltage transmission is feasible since it is a lot easier to transform voltage levels in AC. 
2. On the other hand, we can find DC in almost all electronic devices. Although AC and DC do not work well together, one must transform AC to DC to use an electronic appliance.
3. The frequency of AC is between 50 and 60 Hz, whereas DC has zero frequency.

The Principles of Direct Current

DC only moves in a forward direction, from positive to negative, and is constant in time. As the direction flow remains the same, it provides constant voltage. The frequency is zero, or it often has no frequency as it does not change direction.

DC is produced from batteries and DC generators, and it has constant polarity. It avoids the occurrence of inductance and capacitance. There are two types of DC: 

• Pure direct current
• Pulsating direct current

Pure DC has a constant magnitude, whereas a pulsating DC has a variable magnitude. The loss of electrical energy is very low in an HVDC (high voltage direct current) transmission system. It is much more difficult and expensive to change the voltage of a DC compared to AC. It is used in electronic devices that use batteries as their source of power. 

Examples of DC

The application of DC can be seen in: 

• Batteries, both rechargeable and non-rechargeable
• Solar panels
• Mobiles
• Air conditioners 
• Fans
• Lights
• Sockets
• Flashlights
• Flat-screen TVs
• Electric vehicles
• Computers
• Radios

Advantages of Using DC

• It is energy-efficient because of its constant polarity and magnitude. It is more eco-friendly as it can be generated from renewable sources. 
• DC is used in almost every household appliance. These tools depend on DC supply as DC circuits are noise-free and have low power loss. 
• It can store electrical energy very efficiently.

Disadvantages of Using DC

• DC is very complex. It is sometimes challenging to generate a high voltage because of the commutation problems. 
• Both DC switches and circuit breakers are quite expensive.
• The amplitude of the DC voltage can not be changed. i.e., we cannot step it up or down according to our choice.
• It also causes heating issues and has a high cost of transmission since it requires equipment such as rectifiers and inverters. 
• DC is hazardous when compared to AC.

Conclusion  

Direct current is unidirectional as it only moves in a forward direction, from positive to negative, and is constant in time. As the direction flow remains the same, it provides constant voltage. 

In this article, we studied the examples of DC and how we use them in our daily lives. We also studied, in brief, the advantages and disadvantages associated with DC.