Changing the Wireless World for Light Poles with Intermittent Power

May 30, 2017

Powering an outdoor wireless surveillance system or Wi-Fi network on a light pole presents unique challenges. Many light poles have an intermittent AC power when they are tied to a master photocell or timer. This makes the deployment of active equipment such as radios and cameras very difficult. In these types of deployments, solar systems can be utilized; however, solar systems are large and expensive which makes it a poor choice for this type of deployment. Our engineering team was able to develop a proprietary charging system utilizing battery power during the day and provide seamless power transfer at night combined with fast battery re-charging.

We engineered our Power Extender to 120 VAC nominal input power to 35 watts of PoE output power to drive most wireless radios or cameras. The resulting solution enables seamless power transfer from AC site power to battery reserve ensuring the AP remains powered and radio rebooting is avoided. The system installation is relatively easy using standard RJ45 Ethernet connections to supply power from the enclosure to the POE devices. In order to create a complete system and durable product, the 18x16x12” enclosure is NEMA 4X, constructed of powder coated aluminum with latch locks for protection and easily pole mountable.

One Texas School System network engineer learned about our new power extender, which provides a solution to this very challenge. The scope of the project included deploying security cameras in close proximity to the students, faculty, their cars, and other areas of the school that require monitoring. The desire for the project was to use the campus light poles, however, they were all tied to a master photocell and had intermittent AC power available during the nighttime only. The school system looked at several more options including installing the cameras on buildings further away from the target location as well as rewiring the light poles to add constant power. A benefit of the Power Extender system was that the pole mounted device was able to easily retrofit into the current infrastructure. The cost and time to rewire the site was problematic for the overall project budget and timeline.

Our power system engineer, Jim Baker, performed some enhancements to the standard Power Extender to accommodate the specific requirements for the school system. The schools network employed an outdoor Wi-Fi access point for backhauling the camera data and each light pole needed to accommodate 4 cameras. Further, the AC power available at the light pole was 480VAC. The challenges were overcome by:

• Increasing the battery bank size to 200Ahr to accommodate the total active load for 18 hrs each day. Sizing was determined via temperature compensated battery capacity equations developed for the specialized sealed lead acid batteries. The minimum temperature of the deployment region was used to maximize the battery bank life cycle. The batteries where selected due to increase in the depth of discharge and cycle life for the application. Utilizing a transformerless design of the charging system to accommodate the 480VAC input the Ventev Power Extender charging systems is a combination of a 12VDC battery charger and power supply. The system was designed for site voltages of 180-528VAC. The power supply feeds the load while the battery charger recharges the battery independently from the load current. When the AC power is removed, the power seamlessly changes between the power supply and the battery bank. The compact size allows for more customer equipment to be deployed inside the enclosure.

• The Ventev Power Extender charging system has a pre-set LVD when the battery is being used. A two minute timer is used in order to prevent premature of false disconnects when the battery voltage drops below 10.0VDC. If the battery recovers to above 10.0VDC prior to the elapsed two minute, the battery remains connected to the load and the timer is reset.

• Increase the number of PoE outputs to accommodate four PoE cameras and one PoE+ wireless access point.

Security Cameras mounted on Light Poles

Ventev’s unique solutions make us a leader and innovator in the Wi-Fi industry. Our team will work with you on system customization and designs to fit the specific needs of your deployment.

For more information on Ventev’s products, and solutions visit the links below

Link to School System Case Study

Link to Power Extender

Link to Power Solutions Products

Leave a Reply

Your email address will not be published. Required fields are marked *