Power when you need it

Midspan technology powering devices over networks drives PoE growth for security


It's a little black box packed with the power to run technology over Ethernet cabling. With multiple ports to support future needs, the midspan has the capability to power an array of devices from VoIP to motorized PTZ cameras. Powering devices over networks is experiencing tremendous growth due to the midspan's efficiency to deliver power and the industry's insatiable need to run it more effectively. Midspan manufacturers are eager to meet the industry demand for increased power often staying ahead of current standards with power supplied exceeding what is called for.

Power detection

With the introduction of VoIP the race was on to add and power additional technologies. Ethernet technology is where the capacity to safely power devices continues to change. The challenge of course was how to deliver this power without overloading the circuits.

"Before there were standards for power, the need for PoE dated back to 2000 for powered devices," explained Sani Ronen, senior product marketing manager for Microsemi PowerDsine Midspans, Irvine, Calif. Providing power safely according to the standards is done without it being live all the time. "The midspan detects if the device on the other side needs to get power-if the midspan notices the signature of a device then it delivers the power-the power is only delivered when needed," continued Ronen. If power is always being sent out over the lines there would be too much of it carried over the Internet cable, resulting in possible damage. Thus, the midspan device was developed to power up technology only when needed. This makes it safe and energy-efficient.

One of the greatest advantages of the midspan is the ability to take it out of the box, plug it in and begin using it. But there are other benefits as well.

"The most obvious is the midspan allows you to add power over Ethernet to a variety of applications: VoIP, wireless access points, security cameras, biometric devices-anything that can handle PoE without replacing switch infrastructure," said Jeff Snowden, sales manager, SEI Power, Frederick, Md. "As a result, there is a faster turnaround time, a faster install and it certainly is less expensive than doing a turnkey forklift replacement of your switches," he continued. The company offers a midspan product that allows users to add a battery pack without having to upgrade their UPS (uninterruptible power supply) systems.

Powering the midspan can also be accomplished through AC or DC power sources and this depends on the location of the peripherals and the cabling required. "The midspan is typically an AC powered device," Snowden added. However, SEI also makes a DC powered version which is helpful for data centers or other locations that have a DC plant or a DC UPS. "You can plug our DC version in and that DC power directly-at this point the midspan becomes an intelligent PoE compliant patch panel," said Snowden.

Select your cable wisely

Choosing the right cables is also important and based on the power standards, Category 5 is recommended, however, Category 3 can be used.

"Cat 5 is used because of the gauge of the wire-it delivers better quality and the high level of power being sent through it is best handled with Cat 5," Snowden explained. The recommended use, Snowden added, "Cat 5 is for data use while Cat 3 will handle telephony applications-traditional analog signals. The connection is not as clean or standardized and the gauge of the wire is different." Honeywell, Morris Township, N.J., recently announced the introduction of its Cat 6 line, further evidence that the industry is future-proofing for increased power delivery which will be necessary as products continue to evolve.

"The issue is, there are more devices that need more power," Ronen added. As part of the next working group to work on standards for increasing power, Ronen noted, "when you move to higher power, the current level on the cable is getting higher. The new standard will take up all four cable lines out of eight in order to keep the current low. Some vendors have already designed a four-pair PoE," he said. Many of these products will hit the market before the next standard is written, which is expected to be out within three years.

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