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 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.

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.

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.
Advantages	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.
Disadvantages	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.

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.

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.

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.