Is PoE AC or DC Voltage?

is poe ac or dc voltage?

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Are you searching for PoE switches for your enterprises? Do you want to know whether PoE has Ac or DC voltage? Well, stick to this article while I answer all your doubts.

PoE is a DC voltage. There can be several reasons why manufacturers make PoE switches work on DC voltage. I will explain all those reasons shortly. But we will have to explore this switch more beyond a short answer.

AC stands for Alternating Current. An electric current periodically reverses direction and changes its magnitude with time in contrast to a direct current.

We can define DC as a unidirectional flow of electric charge that can flow through conducting materials like wire. It can also flow through the semiconductors.

Why Do We Use DC Voltage in PoE?

PoE switches help us connect different devices within the network. So why do we use direct current in PoE? Let’s find out the answers to this question.

We use DC in PoE because DC doesn’t pass the Ethernet transformers. Nevertheless, the engineers tried both AC and DC voltage. In conclusion, they found that an AC voltage passes the transformers and creates considerable interference on Ethernet communication.

As we also know, all computer components require DC voltage to perform their functions, so it is mandatory to send DC voltage instead of AC. However, PoE-compliant devices accept power from either source. Thus, we use DC in PoE. Here you can find what devices use PoE.

These are not the only important reasons for using DC in the PoE. There can be several other reasons for supplying DC to the PoE. Some of the other notable reasons for using DC in PoE are as follows.

  1. DC voltage is more energy efficient.
  2. DC voltage helps to operate electrical equipment
  3. DC voltage helps in storing current in a capacitor with a rechargeable battery.
  4. DC voltage has variable engine speed.
  5. DC voltage has no reactive losses.
  6. DC voltage is easy to manage and convert to higher or lower voltage using transformers.
  7. DC voltage always flows in the same direction.
  8. DC voltage is suitable for the low current application.

Well, I can count more, and this list can go much beyond these points. I hope now you understand the benefits of using DC.

AC Vs. DC Voltage in PoE

DC voltage is suitable and safe for the PoE switches. As I said earlier, the engineers have tried both ones, but DC was favorable for the PoE switch.

AC power has frequency because it alternates back and forth periodically. But DC power flows in one direction. So you can differentiate them by looking at their waves. AC power makes a wave-like Sinusoid pattern, whereas DC power has a flat line.

AC power is 3 to 5 times more dangerous than DC power. In case of shock, the alternating current can cause the heart to go into atrial fibrillation, but the continuous flow of DC is not as dangerous as AC power.

You can experience electric shock when there is a complete path with a couple of contact points on the body as it helps the current enter and exit.

However, you may still get shocked by a disconnected cable because power sourcing equipment must experience a handshake with the powered device before passing any power supply.

But the PoE switch is much safer. That’s all because this switch uses DC. Besides, I suggest you read how to choose the power of the PoE switch to avoid any alarming events.

Why Do Manufacturers Consider DC Voltage for PoE?

PoE switches use DC voltage over AC voltage because the alternating current is not favorable for the electronic devices, as it passes through the transformers that create unwanted problems.

That’s why the manufacturer uses DC for the PoE switch. But, moreover, there can also be other reasons for considering DC over AC for the PoE switch.

Some of the other key reasons for considering DC voltage for PoE are as follows.

DC Voltage Is Safe

DC power is much safer and efficient than AC power. That’s because DC power has no frequency as it flows in one direction. On the other side, AC power has dangerous amperage levels, leading to severe results in case of shock.

Computer Equipment Require DC Voltage

As we all know, computer equipment requires DC voltage for proper functioning. In addition, computer devices may need a steady yet unidirectional flow of electrons to operate and store data.

Thus, users need to supply DC power to operate their devices. That’s another reason why the manufacturers design their PoE switches to run on DC voltage.

DC Voltage Fails to Pass Transformers

DC does not pass the Ethernet transformers. Instead, transformers block the DC voltage and pass the AC voltage.

AC voltage creates a disturbance on the Ethernet communication. Thus, it is impossible to use AC on the PoE switch. In short, I would say it is not suitable.

DC Voltage Supply Electricity With Greater Efficiency

Manufacturers use DC voltage in the PoE switch because it helps transmit electricity with greater efficiency over huge distances.

It uses high voltage direct current transmission that transmits contemporary with better efficiency than alternating current.

How Does PoE Work With the DC Voltage?

As we know, PoE uses DC to perform its activities. But have you ever wondered how PoE works with the DC voltage? In the case of PoE, two different devices are involved. One is Power Sourcing Equipment (PSE), and the other is Powered Devices (PD).

Powered devices are involved in the PoE switch because it accepts low voltage power transmitted over structured internet CAT 5 cabling. And power sourcing equipment helps to provide DC power to powered devices.

Power sourcing equipment supplies 12 watts of power at 48 volts to each powered device. It can be an end-span device or a mid-span device. An endspan device provides PoE power on each port, and a mid-span device connects to each end device that adds power to the line.

Power can be carried over the cable using two methods.

Alternative 1

It is the first method of carrying power over the cable. It uses a simplex or phantom feeding method for delivering current to the end device. Standard Ethernet CAT-5 cabling uses two signal pairs connected to pins 1 and 2 and pins 3 and 6 on RJ-45 connectors.

Power sourcing equipment helps provide power on these pins through the center tap of internal signal coupling transformers. Now, powered devices derive power from these lines using the reverse options.

Alternative 2

You can also supply power to the cable using this method. In this alternative, one can pass the power over spare wire pairs in the cable.

Final Thoughts!

Thus, PoE switches use DC over AC because AC passes through the transformers and creates several problems with Ethernet communication.

PoE switch is the electronic device that connects different computer devices to the network. As we all know, computers or electronic items always use DC voltage because it is safe, and it supplies the current at good efficiency using high voltage direct current transmission.

PoE switch uses DC voltage that helps to enhance efficiency, improve power reliability and quality. So, if you are planning to get a PoE switch for your business, go for it. Be it a 14-ports PoE switch or a simple PoE extender, get your hands on the proper devices. By this, you can remove the distributed wall sockets and select the modern switch for easy connection to your devices.

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Hi, I'm Mr. Hua, The funder of HoweVision technology, I'v been woking industrial communication equipment for 8 years now, and the purpose of this article is to share with you the knowledge related to industrial communication from a China supplier's perspective.

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