Wireless Spread Spectrum Radio SCADA for Water Facilities

• By Dan Steele
• Apr 29, 2010

Radio communication and its flexibility offer cost and labor benefits to newly deployed Supervisory Control and Data Acquisition (SCADA) systems as well as a means to enhance the performance of existing SCADA systems.

As water/wastewater facilities expand to meet population needs or upgrade to comply with permit requirements, more generation/distribution, lift stations, and treatment facilities will be needed. Many municipal water systems have had to broaden the area from which they gather, use, and reclaim water while trying to stay within shrinking budgets and manpower cutbacks. Facility managers understand the usefulness of electronic data gathering, but up until now, SCADA and using high-speed unlicensed spread spectrum radios with serial and Ethernet ports has been a "want" instead of a "need."

Data System Integration The first issue to resolve when transmitting data from one point to another is protocol. ModBus is a protocol that has, for the most part, become the industry standard for a majority of field devices. It also is the most common industrial Ethernet protocol, enabling users to pass data from older to newer technology. Data integrators often will use ModBus for areas where small pockets of input/output (IO) data are to be gathered and transferred to the system's "backbone" ─ where the data is sent to the main control and gathering area. This is where the term SCADA originated.

For the City of St. George and Washington County Water Improvement Districts in Utah, getting reliable and accurate data from hundreds of IO points scattered throughout more than 100 square miles and elevations ranging between 2,000 to 9,000 feet was a significant issue. The districts faced these challenges:

• monitoring a wider area for the source and use of water,
• determining the type(s) of network and arrangement,
• developing protocols and conversions.

The Water Improvement Districts' backbone system is more than 100 linear miles in length with branches covering many more miles. The IO count is in the thousands, with more than 200 data sites. The sites are a mix of utility- and solar-powered devices, with the solar sites designed to perform for several cloudy days without interrupting service. The combination of hardware with the ModBus protocol has minimized the need to replace or upgrade field hardware.

SCADA solutions like this are growing because they:

• eliminate the limitations and cost of wired systems. Radio technology improvements, including Serial and Ethernet capability and Modbus protocol for IO applications, now allow for innovative control and monitoring of SCADA systems.
• bring monitoring points (such as wells, lift stations, storage tanks) to an end user's fingertips without the expense of running wire or fiber to remote locations.
• coordinate licensed and unlicensed radios to provide the speed and security to build robust, professionally designed SCADA networks.
• prolong the usefulness of existing equipment and ensuring years of reliable SCADA network operations.
• create the flexibility to expand communication capabilities to meet the requirements of fast-growing, high data service areas and SCADA operations.

The Wireless Difference Wireless communications allow water/wastewater users the flexibility to bring on new locations and new applications into their SCADA system without interference from any pre-existing communication network, such as fiber or hard wire. This type of network also does away with the need for permits to trench for underground conduit lines as well as the cost of wire and junction boxes and installation and maintenance labor to bring data from existing remote pumping stations, treatment plants, or water tanks to the current SCADA system. Wireless can typically be installed for one-third to one-half the cost of fiber or hard wired systems.

Water/Wastewater managers should consider all the financial and reliability costs involved in wired networks. Fee-based lease lines or cellular technologies put water utilities at the mercy of their providers ─ the water facility's network will come up when the vendor’s network does (and only then). Control costs often are based on the repair itself, technician time, and fuel for the service call. In addition, wired networks often cannot provide communications for all equipment and locations.

Wireless radio-controlled SCADA, on the other hand, gives users real-time access, control, and monitoring of all the devices and functions within their network. They can manage their system's requirements using fewer bodies and man hours. These systems allow water facility staff to monitor cathodic integrity for corrosion, use IO radios to get information on tanks, or simply check pump stations at wells.

Another advantage for the water/wastewater industry is the fact that water districts (county and city entities) in large metropolitan areas often overlap in coverage. These districts can minimize costs by sharing the same backbone and/or data points. Through memoranda of understanding, water agencies can stipulate which data they are willing to pass through the joint system. Most large districts have their own IT departments, and once they are assured everything in their world is secure, they are very helpful in setting up security and routing data to the correct system points.

Wireless technologies are positioned to meet specific challenges beyond just wiring costs for the water/wastewater industry. Shedding wires provides unmatched freedom and flexibility to creatively solve difficult challenges and allows adopters to deliver a major, positive impact to their respective organization’s bottom line.