In this era of utility deregulation, a new predictive science for electrical distribution systems is evolving, aimed at increasing power reliability in industrial, utility and commercial applications. Many enterprises already perform predictive maintenance in some areas of operation; now the technology exists to extend predictive maintenance practices to power delivery systems and infrastructures -- efficiently and cost-effectively.
Diverse infrastructure management programs have been developed with the goal of attaining 100 per cent uptime or system availability, particularly in facilities with mission-critical applications, e.g., e-commerce enterprises, financial institutions, medical facilities and, to an increasing degree, manufacturing plants.
These programs consist of an array of products (UPS, transfer switches, generators, etc.), procedures and strategies designed to maintain power delivery systems at the highest levels of integrity and availability.
Power as Raw Material
Industries and businesses of all types are constantly seeking ways to improve their quality and productivity to remain competitive and profitable. Many companies have introduced quality circles, as well as total quality management programs that examine their raw materials and their processes. It is standard practice to subject raw materials and components to incoming inspection. Electrical power is not often thought of as a raw material, but it is vital to virtually all types of manufacturing. The quality of power is therefore of concern to many businesses; for example, power disruptions in a semiconductor fabrication plant can result in millions of dollars of lost production. Semiconductor manufacturers go to great lengths and expense to ensure the quality of one particular raw material, water, and continually monitor its purity. The purity of water is just one of many indices of quality that is tracked in a manufacturing industry. It is also now possible to develop quality tracking for power.
Unlike many raw materials, power has the unique property of being consumed as soon as it is generated. It cannot be stored to be analyzed for quality in the future. If power quality is unsatisfactory it cannot be recycled or repaired and returned to the process. It must be monitored continuously and its quality established in 'real-time'. Since many manufacturing processes depend on computers and other electronic controls, the continuous monitoring of power is becoming more widely adopted.
Monitoring systems are often installed to determine the amount and cost of energy consumed, but for many industries (such as semiconductor manufacturers), the cost of power disruption can outweigh the energy costs. Power quality and harmonics should be monitored along with consumption. To meet these needs, this new generation of monitors is now available at affordable prices that comprehensively monitor all aspects of power, and play a role in total quality management.
Early Warning Systems
Predictive maintenance techniques have long been employed to prevent operating loss in mechanical equipment such as engines, motors and generators. Similar early warning of potential problems in electrical distribution systems can now be achieved, using a new generation of monitoring instruments that capture power information in great breadth and depth and powerful software tools that analyze trends, identify deteriorating conditions, and pinpoint areas for preventive action.
Traditionally, power quality monitors have been used to perform postmortems after problems arise, such as computer or electronic equipment malfunctions. Monitors programmed with thresholds or set points may not record incipient events, or data may be inconclusive. The sheer mass of data collected may be overwhelming, making it is impossible for users to analyze and answer simple questions: "Is power quality improving? Deteriorating? Are other disruptions imminent?"
Until recently, these issues have been impossible to address. Significant technological advances -- full disclosure monitoring, using adaptive threshold techniques -- have made predictive maintenance for electrical distribution systems possible, enabling engineers to answer these questions and profoundly improve power system reliability. Comprised of robust, technologically advanced power monitoring instruments and customizable software to analyze data, full disclosure monitoring systems are powerful tools for managing energy consumption and costs, isolating trouble spots, analyzing power quality trends, and developing predictive maintenance programs. Using digital signal processing, high-speed sampling and personal computers to capture and store all aspects of power performance in archivable databases, these systems provide facility managers and operators with comprehensive, real-time information about electrical energy resources.
Full disclosure monitoring systems utilize digital signal processing, real-time data collection and performance analysis software to provide engineers with comprehensive power quality information.
Full Disclosure Benefits
Full disclosure power monitors differ from conventional monitors in two major respects: they do not require thresholds or set points to isolate power disturbances; and they capture all aspects of power in great detail, including power disturbances, harmonics, flicker, power consumption, and characteristics not normally seen by devices utilizing manually preset thresholds. By tracking these conditions over time, degeneration in the power system that would lead to a loss of efficiency or failure becomes apparent.
The low cost of comprehensive power monitoring makes it economically feasible to continuously monitor multiple locations. Benefits include:
Postmortem data on disruptive power disturbance incidents, indicating how and where events were caused, how to avoid them in the future, and how to mitigate their effects.
Continuous monitoring of harmonics to ensure that incremental load additions do not contribute to premature failure of power components.
Data collection and tracking to determine if adequate and appropriate investment in the infrastructure is being made, and for planning future expansion.
Permanent databases for comparing current and historical conditions to predict incipient failures.
Advance warning of deteriorating power situations provides the opportunity to correct them before disaster strikes. In mission-critical operations, prevention yields enormous economic benefits by ensuring continuous system reliability and availability.
Tracking Power Fluctuations
A predictive maintenance program is established by installing monitors at critical locations. Each monitor performs a survey for a reasonable business period, e.g., a week or month. When a survey is finished, data is downloaded and saved; the monitor automatically resets to perform subsequent surveys for the next period. Multiple databases collected over many periods -- typically a year or longer -- provide engineers with a comprehensive history of plant power operations or utility consumption. Continuous tracking of changes in the power situation and comparison of events and trends on a regular basis highlight anomalies and deteriorating conditions.
The initial survey establishes true baseline conditions to provide the basis for accurate comparison to subsequent survey data. With full disclosure monitors, each subsequent database is a faithful record of the true conditions at each moment in time. Each survey is a faithful snapshot of power quality at every point in time.
Managing Information
Full disclosure monitors capture values much lower than conventional 'old technology' monitors, recording the underlying quiescent data that indicates incipient problems as well as severe events. Only full disclosure monitors establish true conditions at all times throughout the data collection process -- at the inception of the predictive maintenance program and on an ongoing basis.
Complete power reliability is measured in terms of 100 per cent availability or uptime. How then to prevent disruption and damage and get advance warning of an impending problem?
Power monitors collect large volumes of data but it must be analyzed to provide information that gives operators an understanding of their system's condition.
Predictive maintenance software gathers and manages the vast amount of data collected from multiple monitors. Using database formats, users can merge, compare, trend and manipulate monitoring data. These tools provide unique features for interpreting power monitor information and customizing analytical reports and presentations. Converting data to information leads to knowledge and provides a framework for preventive action.
Full disclosure monitors are available for portable or embedded (permanently installed) applications. Predictive maintenance software warns of incipient faults before they cause the distribution system to fail. Only these systems capture and analyze the information necessary to implement effective predictive maintenance for a facility's electrical distribution system.
Michael Daish is with Reliable Power Meters. ET