by Jonas Olsen, On-Ramp Wireless
Traditionally, equipment maintenance has been manual, reactionary or event-based. Something breaks down, an alert is created and the problem is corrected eventually. This antiquated approach leads to costly delays; minor failures can bring parts of a distribution network down. A more preventative, proactive maintenance system is required.
This is the origin of condition-based maintenance (CBM), also called condition-based monitoring. With CBM, sensors are deployed in the production line and data is collected and analyzed for finding early warning signs in attempt to correct issues before they become major obstacles. The goal is to move from time-based maintenance (checking the valve weekly) to just-in-time maintenance (fixing the valve just before failure).
CBM lowers costs in five primary areas:
- Reduced outages because of early warnings;
- Replacement deferral;
- Substitution of current manual processes;
- Operational efficiencies; and
- Safety improvements.
CBM deployment requires a cost-benefit analysis between the cost of deploying and maintaining the system and the gained benefits of preventative or just-in-time maintenance. Often the cost of deploying CBM systems in utility and other wide-area networks has been too high to justify. In some situations, there hasn't been a technology that could solve the technical challenge.
A wireless communication system, however, can mitigate most problems with CBM and provide customers with a short return on investment and continuous cost savings. In the case of San Diego Gas & Electric Co. (SDG&E), the utility implemented such a system to aid in the maintenance of its warning lights, Federal Aviation Administration (FAA)-required indicators affixed to transmission towers that warn aircraft of possible flight path obstructions. For SDG&E, wireless communication has proven cost-effective and viable to ensuring its FAA lights function at all times.
SDG&E Monitoring of Aviation, Obstruction Lighting for FAA
SDG&E's service territory has some 1,800 miles of overhead transmission lines in towers, most of which are in hard-to-reach, outdoor environments. FAA regulation AC No. 70/7460-1K for L-810 and L-864 states these towers must be equipped with solar- and line-powered obstruction warning light systems, which must be monitored constantly. SDG&E monitors manually by sending trucks and helicopters to visually inspect the lights every day, which is not cost-effective.
SDG&E implemented an automatic monitoring and fault alarm notification system to detect all light failure conditions (light failure or outage, solar- or line-powered substation failure and intrusion detection). The system needed to remotely monitor sensors and provide detailed status reports at consistent intervals. Because the system constantly monitors light conditions, it also must be low-power to minimize manual battery recharging or replacement. Solar power provides ongoing operations. SDG&E implemented remote monitoring units operating in the unlicensed 2.4-gigahertz ISM band, eliminating the need to visually inspect the obstruction lights daily. The system was field-tested and proven in high electromagnetic field (EMF) and electromagnetic interference (EMI) environments typical for transmission towers and substations (up to 500 kV). This flexible monitoring platform provides many miles of coverage and can measure analog and digital signals from various sensors. The solution provides a detailed audit trail of device status alarms and events. Alerts may be emailed or sent by text message so SDG&E employees receive real-time notification of light issues. Service personnel can take immediate, corrective action. The deployment resulted in reduced operations and maintenance cost and lowered critical infrastructure risks.
Wireless communication systems offer tremendous cost-saving opportunities through elimination of manual processes, enhanced error alerting, increased safety and better maintenance, and they enhance customers' competitive advantage and present new revenue opportunities. This could not have been achieved at SDG&E without the performance breakthroughs and significant cost advantages of the technology.
The unlicensed 2.4-gigahertz wireless system can cover most wide areas of operation with minimal network planning. Current solutions typically fail because of limited range and capacity and a too complex network architecture. In contrast, this new technology offers simple, secure wide-area coverage in a low-cost package for most equipment- and condition-monitoring applications.
Jonas Olsen is vice president of marketing and business development for On-Ramp Wireless. Reach him at email@example.com.
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