| The security industry’s continued migration to networked IP-based systems ensures that PoE will be integral in their design and installation |
Power over Ethernet (PoE) has without question become the de facto choice of security installers for delivering power to security and access control devices. This should come as no surprise given PoE’s ability to reduce labour and installation costs by delivering power and data over a single cable, thereby increasing overall total cost of ownership (TCO) and return on investment (ROI) for installers and end users alike.
Game changer for deploying power
While PoE has become a game changer for deploying power, a significant amount of knowledge is required to ensure things go smoothly. For starters, we need to understand the way power is delivered over different cable types and distances. The power consumption of IP cameras and accessories must be considered to accurately calculate the total power required for proper system operation. Additionally, there are a number of adaptive transmission solutions available that enable PoE to be delivered over coax cable and further extending Ethernet range.
Key factors to consider while selecting power supplies
The following is an overview of important factors to consider when evaluating and selecting power supplies that will be most efficient for your specific application
- Estimate the correct total power consumption
When specifying PoE it is important to correctly estimate the total power consumption for a system. Should you underestimate power requirements, you may not discover the mistake until late in the installation process, which will lead to costly problems. The fallout associated with this will most certainly cause system failures and possibly harm your relationship with the customer. Future system expansion and distance should also be considered when specifying power.
- Account for voltage drop
There are two established PoE standards: IEEE 802.3af (PoE) and IEEE 802.3at (PoE+). PoE provides 15 watts with 12.95 watts available to power network cameras and other devices over either the data pairs (mode A) or spare pairs (mode B), depending on the design of the power source. PoE+ provides up to 30 watts over either mode with 25.5 watts available to provide the extra power to operate PTZ cameras with heater/blowers, as well as other devices.
A main advantage of deploying |
PoE and PoE+ are the only “official” standards, but there is a third option, Hi-PoE, which delivers twice the capacity of PoE+ over the same infrastructure. Special midspan injectors allow Hi-PoE to transmit using both modes A and B to provide up to 60 watts. This is primarily delivered using two separate 30-watt PoE+ feeds transmitted from a single port. Although manufacturers know that “pure” Hi-PoE works, they may be cautious about implementing it into their devices without an official standard, choosing instead to use two PoE+ feeds. So even though a device’s specification says 60 watts – which is 100 percent accurate – it’s crucial to account for voltage drop along CAT5E or CAT6 using the same distance limitations of PoE+.
Significant savings and easy installation
A main advantage of deploying Ethernet over coax is the ability to cost-effectively upgrade analogue to IP without the need to rip and replace existing infrastructure. In addition to transmitting video and data signals over existing coax cable, these solutions can pass PoE, PoE+ and even Hi-PoE over a single cable to assist with deploying multiple cameras or edge devices. This makes it possible to cost-effectively expand a system’s capacity. The savings from deploying Ethernet over coax solutions can be quite significant.
Ethernet over UTP solutions allow legacy UTP infrastructure to be easily upgraded to accommodate IP cameras and devices. These solutions transmit video/data up to 150 metres – 1.5 times the distance of conventional Ethernet. Units also pass power to cameras and edge devices from virtually any midspan or endspan, providing a cost-effective plug-and-play IP solution that is easy to install and implement.
There are single and multiple output midspan injectors that can provide PoE, PoE+ and Hi-PoE to complement virtually any edge device or adaptive transmission solution (Ethernet over coax, Ethernet over UTP, etc.) to provide versatility and flexibility for design and deployment of security systems. Multi-port midspan injectors are available for indoor and outdoor use, making installation and deployment convenient.
All of these factors can help to ensure adequate power is delivered to IP devices while reducing overall time, effort and cost of installation. The security industry’s continued migration to networked IP-based systems makes certain that PoE will continue to play an integral role in their design and installation. Therefore, it’s imperative that security professionals fully understand the nuances of PoE.