What is an AC power source?

What is an AC power source?

What is a power supply?

A power supply is a device to provide the electric current that comes from a power source to the type of electricity you need, including motors, computers, and other electrical devices. The main objective of a power supply is to convert electric current to the proper voltage to power the load. With correct voltage and frequency, the electrical devices can function normally.
The two different types of power at the input and output are alternating current (AC) and direct current (DC). In the paragraphs below elaborate the differences of AC and DC.

What is AC Power?

AC power (Alternating Current power) refers to electrical power flowing in alternating direction, and it is the standard electricity format that comes out of outlets. The typical waveform for an alternating current is a sine wave. This form of power is most commonly delivered to residential and industrial customers through transmission lines. A major advantage of AC power is that its voltage can be modified relatively easily using a transformer, Preen’s AFV-P Series has the Transient feature, users can have more control over the waveform by inserting disturbance at user-defined sites with user-defined drop/rise ranges. This is a useful feature to simulate different pre-compliance tests and various types of power line disturbance, such as surge, sag, spike and dropout, for immunity tests. AFV-P Series can sustain inrush current up to 9 times of max. output current. The user doesn’t have to purchase a high capacity power supply due to the load’s high inrush current .Moreover, because of the wave-like motion of AC power, it can travel farther than DC power.

What is AC Power?

(AFV-P Series High Performance Programmable AC Power Source)

Single-Phase and Three-Phase Power Supply

An AC power supply might be a single-phase or three-phase power supply. A single-phase power supply is the distribution of AC from the power line through the load, and back through the neutral wires. Single-phase power supply is a common method to supply AC current to individual residences and business offices. On the other hand, a three-phase power supply consists of three conductors to transfer AC with a phase difference of 120°. A three-phase power supply is a more economical and efficient way to deliver electricity, since three-phase power supplies contain less materials of conductors to transfer the same amount of power.
A three-phase AC is especially used for high-voltage power transmission.The AFV+series is featured of the three phase independent adjustment. Users can press the icon on the main page of the touch screen to quickly switch from balanced voltage setting to independent voltage adjustment setting. The AFV+series is ideal to simulate different regions' voltage and frequency conditions, and can cover applications for domestic appliances, motors, medical equipment, lighting and EMC laboratory.

High Power Programmable AC Power Source

(AFV+ Series High Power Programmable AC Power Source)

What is DC Power?

DC Power (Direct Current power) refers to electrical power flowing in only one direction. This current mostly comes in the form of batteries, solar and fuel cells. Because DC power delivers consistent voltage, most electronics require this power type. You can see many electronics in our daily lives have batteries of the devices or need to convert AC power from the outlets to DC power through a rectifier. By doing so, the delicate components inside electronics devices will not be damaged by the highs and lows of alternating current.

Why are there Two Different Power Types?

We use both AC power and DC power in our daily lives, but we are not very familiar with these two types of power. You may wonder if it is necessary to use two different power types. The answer is yes, but why?
Today, alternating current continues to dominate the electricity on the market. Power outlets bring AC power into buildings, where this current may need conversion into DC power since many electronic devices today still require the consistent, steady voltage of power. Therefore, both types of power are equally essential, and we cannot live without one of them. AFV-P Series is a programmable AC power source with DC output and precision measurement. It not only provides AC output to simulate real world grid conditions, but also can generate DC output based on the user's settings. It is an ideal cost-effective power testing solution for R&D and certification laboratories. That is the reason why testing for AC & DC are also important, which our AFV-P series is capable of.

What is DC Power?

Although AC power can be easily converted to DC power if required, DC power still cannot be totally replaced by AC. The main reason is that AC power transmitted power through lines whose length are not limitless, so if we use everything with lines, our living space will definitely be confined. To put it in other words, battery power, fuel cells, or solar cells, which provide DC power, are more readily available than AC power from electricity lines.
Because both electricity types are still in use, sometimes you will need to convert the voltage. In this case, you will need an AC-DC power supply which can convert the voltage into direct current and adjust the voltage up or down according to the device you are using.

What is the Difference Between an AC and DC Power Supply?

It’s very clear that AC power supply is a device that supplies AC power, and DC power supply is a device that supplies DC power.
As we mentioned before, the main difference between AC and DC power is the direction of electrons flow. AC power, flowing in alternating direction, uses electrons that move like waves, whereas DC uses electrons that move in a straight line, flowing in only one direction.
Because AC power moves in waves, it can travel a lot farther than DC power. Preen's AFV+ series has the following traits which can meet the requirements, utilizing advanced PWM technology to deliver power with THD œ 0.5% and up to 2000kVA.
Power plants can easily generate large amounts of AC power and deliver it through power lines, and the voltage will be stepped down to an acceptable level when it reaches homes and businesses.

What is the Difference Between an AC and DC Power Supply?

On the other hand, in many laboratories or factories, the DC power supply is located a certain distance away from the DUT, and this sometimes causes voltage drop due to the resistance of the wires. Preen's ADG-L is equipped with remote sensing to compensate voltage drops and provide a stable output voltage,and it allows users to have the desired voltage appear at DUT.
There is another easy way to tell the difference between AC power and DC power sources. Just see whether the electricity comes from an outlet or a battery. Generally, outlets supply AC power, whereas batteries supply DC power.

Items AC power supply DC power supply
Flowing Direction Alternating direction. One direction.
Electric Current Wave-line motion (a sine wave).
Straight line.
  • AC power can travel farther very efficiently.
  • The generation of AC is cheaper than that of DC.
  • When AC is supplied at higher voltages, the transmission losses are small compared to DC transmission.
  • AC can easily be converted into DC with the help of rectifiers.
  • Consistent delivery of voltage to electrical devices.
  • In DC System, there is no interference with other communication lines and systems.
  • More readily available than AC power.
  • Interference with the neighboring communication lines.
  • At high voltages, it is more dangerous to work with AC than DC.
  • DC power can only run across short distances, making it unsuitable for the electrical grid.
  • Due to commutation problems, electric power can’t be produced at High (DC) Voltage.
Electricity Comes From... Most outlets. Batteries, solar and fuel cells.
Applications Preen's AC power supply can be utilized for home appliances, laboratory, industrial power supply, electric vehicles, renewable energy, military, aerospace and medical industry. Preen’s DC power supply includes renewable energy, electric vehicle (EV), power battery IT/SMT production line and motor & compressor.


How Does an AC/DC Power Supply Work?

Whether you choose an AC-DC or a DC-DC power supply, the objective of a power supply is to power the load with the proper voltage and current. A power supply can be external, often seen in devices such as laptops and phone chargers, or internal, such as in larger devices such as desktop computers.
Each AC-DC power supply may have its different design configurations, but basically, it all has three primaries and necessary components which are transformers, rectifiers, and filters.
First of all, in order to provide a reliable source of DC electricity to a device, the AC voltage will be stepped down by transformers. Secondly, rectifiers will take AC electricity from a source (such as mains power) and convert that energy into DC electricity. Last, a filter will remove some of the electronic noise from the high and low AC power waves. These are the three main steps that how an AC-DC power supply works.

Types of AC/DC Power Supply

Linear AC/DC Power Supply

A linear AC/DC power supply typically utilizes linear regulators to maintain a constant voltage at the output. Compared to switching AC/DC supply, linear AC/DC works less efficiently and the size of a linear AC/DC power supply is larger.

Switching AC/DC Power Supply

A switching power supply uses the power conversion technology to turn switching transistors on and off rapidly to provide regulated voltage. For instance, personal computer chargers, cell phone adaptors and uninterruptible power supply (UPS), are all types of switching power supplies. With the innovation of technology, switching power supplies have been widely applied in multiple industries due to its compact and lightweight characteristics.
Switching AC/DC supplies play an essential role in the development of electronic industries. Therefore, nowadays switching power supplies are widely preferred and utilized owing to their cost, size, and efficiency.


What will happen if you don’t use an AC/DC power supply?

As mentioned previously, the main purpose of using an AC/DC power supply is to transform the AC into a DC voltage, and then the DC can then be utilized to power different electrical devices. Without an AC/DC power supply, AC cannot be transformed into a stable voltage, which may cause electronic components to be damaged. Moreover, some high AC voltage equipment may malfunction or even explode if not using AC/DC power supply properly.

How Does a DC-DC Power Supply Work?

Sometimes, you will need a DC-DC power supply if the device starts with DC power. Unlike AC, DC power cannot be changed from one voltage to another (step up or step down) using a transformer. Therefore, a DC-DC power supply comes out to solve this problem - to generate regulated output voltage for electric and electronic applications. First of all, DC-DC power supplies often include inverters and rectifiers to convert the DC power into AC power, hence AC power can move into a transformer to change the voltage. After the power supply generates the proper voltage, the electricity needs to convert back to DC power through the rectifier, and thus you can use your devices smoothly.
In order to produce cleaner energy in the output, DC-DC power supplies require regulators to smooth out the signal. You can consider whether your devices need a perfectly smooth voltage. Preen's ADG-L series is designed for low ripple, high accuracy and tight regulation for simulating different DC voltages. With fast transient response and rise time, the ADG-L DC sources are ideal to test DUT behavior to voltage sags, dropouts, ON/OFF tests and complex DC waveforms. Although unregulated power supplies are often cheaper than regulated, we strongly suggest you use a regulated DC-DC power supply for a delicate device.

Application of DC-DC converter

DC-DC converter is an electronic circuit or regulator that converts a source of DC from one voltage level to another. DC-DC converter is widely used in a variety of products from portable devices, including cell phones, computers, and so on. Besides, a DC-DC converter is also one of the key components for electric vehicles, since it converts voltage from the high-voltage battery pack and to low-voltage for electric devices, such as wipers, air conditioners, headlights, stereos, seat heaters, etc.

DC-DC converters influence an improvement of performance on efficiency, reliability, control and even power level. Preen’s programmable DC supply is suitable for high-voltage and low-voltage DC-DC converters testing. The built-in simulation function allows DUT to be tested for voltage and current dropout, spikes and other repetitive testing. With the outstanding stability, precise measurement and user-friendly programmable function, ADG-L series allows users to enter the test data easily and test multiple DC-DC converters in the meantime. Therefore, Preem’s programmable DC supply significantly improves the testing efficiency and productivity compared to the conventional testing solutions. ADG-L series offers output voltage up to 2000V and output power from 5kW to 300kW which is ideal for high power DC/DC converters testing applications. (Learn more details: EV Testing Solution Part II : DC/DC Converter)

How Does a DC-DC Power Supply Work?

(ADG-L Series Programmable DC Power Supply)

How to Know if a Power Supply is AC or DC?

Usually, on the surface of the device writes the form. The easiest way to tell whether it is an AC-DC power supply or a DC-DC one is to see the “input” part. When the input is AC, the device surely is AC-DC. On the other hand, when both input and output parts are DC, the device is DC-DC.

How to Choose a Power Supply?

When choosing a power supply, users should first decide the applications of the power supply. Based on the needs, users might consider some factors including certification, maximum power output, and output voltage regulation.

  • Certification: Standard certifications and are required in order to ensure customers’ safety.
  • Maximum Output Power: For safety, be sure of the range of output power.
  • Output Voltage Regulation: Voltage determines whether the electrical devices would function normally or not. Users should pay attention to the voltage regulation standards.


Why Choose Preen (AC Power Corp.) ?

Worldwide Experience

Founded in 1989, Preen (AC Power Corp.) is a world leader in power supply systems, and has been developing AC and DC power supplies based on the core technology of power conversion. We provide advanced, reliable and cost effective power products including AC power source, DC power supply, regenerative grid simulator, power supplies for aerospace and defense, and line conditioners.
With a corporate office located in Taipei, Taiwan, Preen has three manufacturing facilities and multiple branch offices and service locations worldwide, including the U.S. office located in Irvine, California, to provide services to our customers.

Certificates and Awards

Many of Preen’s products are CE and RoHS certified, in line with international safety standards and environmental friendly development. All Preen's manufacturing facilities have ISO 9001:2015 certifications. We keep rigorous controls on manufacturing processes and plant management to ensure only the top-quality products are delivered.

Preen’s Power Supply Products

Preen provides outstanding products and solutions to different applications, and our products cater to different expectations.
For instance, AFV-P series is a programmable AC power source with DC output and precision measurement. It is ideal for commercial, defense and aerospace test applications from design verification,quality assurance, ATE to mass production.

What is DC Power?

(AFV-P Series High Performance Programmable AC Power Source)

If you would like to cover a higher power application, then AFV+ Series will be your best choice. The AFV+series is a high power programmable AC power source, and this series is suitable to simulate different region’s voltage and frequency conditions.

What is the Difference Between an AC and DC Power Supply?

(AFV+ Series High Power Programmable AC Power Source)

To learn more about our products and determine the best power source for your application, you can visit our pages AC Power Source and DC Power Source for further information.


The most important objective of a power supply is to transform current from one power source to another, and in the meantime transform to proper voltage level. For specific applications, there are different solutions that can meet your needs. You can learn more about Preen’s products on our product page and our products’ applications.