Flexible Dual-RF Design: Using Bridge Mode to Extend Power Grid De-Icing System
When snow and ice accumulate atop transmission towers, they pose a serious threat to the integrity of the power grid. As a result, it is essential for utility companies operating in cold climates to maintain an ice-melting system on their transmission towers to prevent winter power outages. One of the largest power grid operators in China wanted to install cameras and sensors to monitor their de-icing system. Initially, the company wanted to connect all the transmission towers to an existing fiber-based network. However, not every transmission tower in the power grid was equipped with optical fiber interfaces. Splicing these towers to the transmission towers that were already on the existing optical fiber network would have interrupted the fiber network and caused power outages, which was not an option. To solve this problem, the company requested a wireless solution from Moxa that could connect the transmission towers without physical connections to the existing optical fiber network.
• Reliable communication network required to monitor the transmission tower de-icing system.
• Fiber, Ethernet, and wireless capabilities are needed to integrate existing equipment with the new real-time monitoring system.
• Network devices must withstand extreme sub-zero environments to minimize maintenance requirements.
Although similar networks often employ GSM/GPRS solutions, cellular solutions are not well-suited for video surveillance due to the high data throughput required. As a result, Moxa opted to deploy a wireless solution using IEEE 802.11a/b/g communications. In addition, the company wanted to install one access point to serve multiple client devices at adjacent towers. However, if the access point fails, all client devices would be disconnected from the network. Also, differences in elevation and mountainous terrain presented challenges for initial setup and antenna alignment.
Fortunately, the versatility of Moxa’s AWK-5222 industrial IEEE 802.11a/b/g dual-RF wireless AP/bridge/client eliminated both concerns. The AWK-5222 has two independent RF modules that allow the device to be designated simultaneously as a slave device to an upstream AWK-5222 master, and a master device to a downstream AWK-5222 slave. This wireless bridge mode also eliminates the possibility of multi-path propagation.
In addition, the AWK-5222 includes two Ethernet ports; one links to the camera and sensor inside the security box to monitor the tower’s operating conditions, the other links to the unmanaged switch for those towers without optical fiber connectivity.In the event of an emergency, those towers that lack existing optical fiber connectivity can take advantage of the AWK-5222’s RSTP redundancy technology to connect all the transmission towers in the company’s power grid to the existing fiber network. In this way, the AWK-5222 provides reliability at a level beyond standard wireless redundancy and also maintains the safety and reliability of the entire power grid.
• High WLAN throughput enables real-time video for the control and monitoring system and allows immediate response to icing problems.
• RSTP reduces link failures, eliminates loops, and allows remote connection of remote towers to the fiber network.
• Wireless bridge mode prevents multi-path propagation and provides wireless connectivity for up to 8 kilometers, even in severe weather conditions.
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Moxa’s comprehensive line of WLAN and cellular solutions have been successfully implemented in various mission-critical industrial applications, including transportation, factory automation, smart grid, and heavy industry. For more information, please click on the icon to download the Industrial WLAN success stories.