Every year, tens of millions of devices are linked to the network via PoE.
The market is predicted to develop at a 15% annual rate between 2019 and 2025, reaching a global PoE solutions market size of $2 billion in 2025.
What is PoE? What Are The Benefits?
Two feeds are needed for a networked device (camera, access point, IP phone, video conferencing devices, etc.) to function: Data and electricity.
Sometimes, the two distinct cables can be confusing.
By simultaneously transmitting power across the pairs of Category 5e and higher class cables, PoE (Power over Ethernet) technology protects network equipment from overload, insufficient power, defects or errors caused by faulty installation, all while saving time and money.
PoE Types
The IEEE 802.3 standard defines four different types of PoE. The technical specifications are compared in Table-1.
IEEE Standard | PoE Type | Energized Number Of Pairs | DC Voltage Output at PSE | Power Delivered by PSE | Voltage Available at PD | Wattage Available at PD | Max. Current Per Pair |
|---|---|---|---|---|---|---|---|
802.3af | Type 1 (“PoE”) | 2 | 44-57V | 15.4W | 37-57V | 12.95W | 350mA |
802.3at | Type 2 ( “PoE+”) | 2 | 50-57V | 30W | 42.5-57V | 25.5W | 600mA |
802.3bt | Type 3 (“PoE++”) | 4 | 42.5-57V | 60W | 42.5-57V | 51W | 600mA |
802.3bt | Type 4 (“PoE++”) | 4 | 41.1-57V | 100W | 41.1-57V | 71W | 960mA |
PSE: Power Sourcing Equipment | PD: Powered Device
Table-1: Structured Cabling
Key Considerations In PoE Applications
Heat is the most crucial concern in PoE applications. The electrical performance of a cable may degrade as its temperature rises. The heat generated by electricity transmission must be dispersed effectively, and the temperature of the cables must not exceed set limits. Increased heat dissipation is essential for improving physical performance and longevity.
Conductor resistance (DCR) governs the amount of heat generated in a PoE cable. Larger conductor diameters in Category 6, 6A, and 7A cables lower DC resistance and thus power loss (lost as produced heat) within the cable itself.
Each 1% decrease in conductor resistance leads in a commensurate decrease in power dissipated in the cable. Category 6 cables tend to have about 80% of the DCR and hence heat generation of Category 5e.
Cable Temperature Rating
Higher cable temperature ratings enable for more power to be distributed inside the cable and/or installation in higher ambient temperature settings. Temperature ratings for cables are typically 60°, 75°, and 90°C. Higher ratings, such as 200°C, can be achieved for particular applications by using special performing materials.
Conductor Thickness/Resistance and Ampacity
To boost conductor resistance, go for a cable with larger conductors.
In comparison to a Category 5e cable, a Category 6A cable offers less resistance and has a conductor size that is roughly 10% greater.
A higher current carrying capacity (ampacity) is implied by a bigger conductor size; however, when cables are bundled, the temperature rises, reducing the current carrying capacity. Table 2 displays the current carrying capacity (ampacity) for various cable temperature values based on the number of cables in the bundle and the conductor diameter.
Number Of 4-Pair Cables In A Bundle | ||||||
|---|---|---|---|---|---|---|
AWG | 1-7 | 8-19 | 20-37 | 38-61 | 62-91 | 92-192 |
AWG | Temp.Rating | Temp.Rating | Temp.Rating | Temp.Rating | Temp.Rating | Temp.Rating |
AWG | 60°C | 75°C | 90°C | 60°C | 75°C | 90°C | 60°C | 75°C | 90°C | 60°C | 75°C | 90°C | 60°C | 75°C | 90°C | 60°C | 75°C | 90°C |
Maximum Current (A) Per Conductor | ||||||
|---|---|---|---|---|---|---|
26 | 1,00 | 1,23 | 1,42 | 0,71 | 0,87 | 1,02 | 0,55 | 0,68 | 0,78 | 0,46 | 0,57 | 0,67 | 0,45 | 0,55 | 0,64 | N/A | N/A | N/A |
24 | 1,19 | 1,46 | 1,69 | 0,81 | 1,01 | 1,17 | 0,63 | 0,78 | 0,91 | 0,55 | 0,67 | 0,78 | 0,46 | 0,56 | 0,65 | 0,40 | 0,48 | 0,55 |
23 | 1,24 | 1,53 | 1,78 | 0,89 | 1,11 | 1,28 | 0,77 | 0,95 | 1,10 | 0,66 | 0,80 | 0,93 | 0,58 | 0,71 | 0,82 | 0,45 | 0,55 | 0,63 |
22 | 1,50 | 1,86 | 2,16 | 1,04 | 1,28 | 1,49 | 0,77 | 0,95 | 1,11 | 0,66 | 0,82 | 0,96 | 0,62 | 0,77 | 0,89 | 0,53 | 0,63 | 0,71 |
Table-2: Ampacity values according to conductor diameter and number of cables in the bundle for different cable temperature values (For 30°C ambient temperature)
Insertion Loss, Shielding and Jacket Type
Insertion loss is a key aspect when it comes to the security and functionality of the PoE cable.
The ratio of “received and transmitted” signal power can be used to calculate insertion loss.
More power can cause higher amounts of insertion loss, as well as higher cable temperatures, which can cause cable breakage.
Because UTP (unshielded twisted pair cable) cannot properly dissipate heat, PoE twisted pair copper cables are often F/UTP (four twisted pairs overall foiled within a cable jacket).
More crucially, TIA standard 568-2.D allows shielded cables to have a 2.5 times larger insertion loss increase than UTP cables. This guarantees that equipment placed at high temperatures run smoothly.
Installation
To avoid temperature increases, the cables should not be pulled in huge bundles, the bundles should not be too close to each other, and the design and workmanship conditions should be in accordance with the norms.
How To Reduce Heat Exposure?
When designing and implementing the cabling system, you can limit the amount of heat emitted by the cables by doing the following:
- Select Category 6A or higher twisted pair cables.
- Use shielded cables rather than unshielded cables; and decrease cable lengths to lower DC loop resistance and balance increased insertion loss.
- Disperse cables along the route.
- Set a limit of 24 cables per bundle.
- When transporting cables, use perforated or wire mesh cable trays to ensure unobstructed ventilation.
- Arrange the cables uniformly (at regular intervals) across the width of the ceiling.
- If cables must be transported in bundles, place power-carrying cables in the same bundle as non-power-carrying cables to ensure that the heat emitted is evenly distributed throughout the bundle. If there are both power and non-power cables in a bundle, place the power carriers on the outside of the bundle so that heat is released into the environment
- Use Velcro straps instead of cable ties to hold the cables together and keep the bundle loose; cable ties will over-tighten the cables and the heat released will be trapped in the bundle
- Check that the ambient temperature does not exceed 30°C.
Compliance Of Zemecs LAN Cables To PoE
All Zemecs LAN cables in Category 5e and higher support PoE applications.
For many years, T1X series Category 5e, T12 series Category 6, T13 series Category 6A, and T14 series Category 7 cables and termination items have been utilized effectively in PoE applications.
All IP based (IP phones, access points, cameras…etc) devices of leading network equipment manufacturers like Cisco and HP have been running in Type 1,2,3&4 PoE applications according to relevant industry standards.
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- https://www.gminsights.com/industry-analysis/power-over-ethernet-poe-solutions-market
- https://www.prnewswire.com/news-releases/global-power-over-ethernet-solutions-market-to-reach-1-billion-by-2024-301354165.html
- 2018 BICSI Fall Conference & Exhibition Presentations “Selecting Cables For PoE” (Hitachi Cable)