In this era of utility deregulation, a new predictive science for electrical distribution systems is evolving. Many enterprises already perform predictive maintenance. Now, the technology exists to extend this practice to power delivery systems and infrastructures efficiently and cost-effectively. The goal of these diverse infrastructure management programs is attaining 100% system availability—particularly in facilities with mission-critical applications, such as e-commerce enterprises, financial institutions, medical facilities, and manufacturing plants. These programs consist of an array of products, procedures, and strategies designed to maintain power delivery systems at the highest levels of integrity and availability.
Early Warning Systems
For a long time, engineers have employed predictive maintenance techniques to prevent operating loss in mechanical equipment such as engines, motors, and generators. Now, operators of electrical distribution systems can receive early warnings of problems by using a new generation of monitoring instruments. These devices capture information with the help of software tools that analyze trends, identify deteriorating conditions, and pinpoint areas for preventive action.
Traditionally, personnel used power quality monitors to perform postmortems after problems (such as computer or electronic equipment malfunctions) arose. Monitors programmed with thresholds or set points may not record incipient events or conclusive data. The sheer mass of data collected is overwhelming, often making it impossible for users to analyze and answer simple questions such as: “Is power quality improving or deteriorating?” and “Are other disruptions imminent?” Until recently, these issues have been impossible for engineers and technicians to address.
However, one significant technological advancement has made predictive maintenance for electrical distribution systems possible. The system, known as full-disclosure monitoring, uses adaptive threshold techniques to achieve these ends.
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. The system relies on robust, technologically advanced power monitoring instruments and customizable software to analyze data. It also uses digital signal processing, high-speed sampling, and personal computers to capture and store all aspects of power performance in archivable databases—so facility managers and operators have access to comprehensive, real-time information about electrical energy resources.
Full-disclosure power monitors differ from conventional monitors in two ways. First, they do not require thresholds or set points to isolate power disturbances. Second, they capture all aspects of power in great detail, including power disturbances, harmonics, flicker, power consumption, and characteristics not normally seen by devices using 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 feasible to continuously monitor multiple locations. Other benefits include:
Postmortem data on disruptive power disturbance incidents indicates how and where events were caused, how to avoid them in the future, and how to mitigate their effects.
Continuous monitoring of harmonics ensures that incremental load additions do not contribute to premature failure of power components.
Data collection and tracking determines if the infrastructure investment is adequate and plans for future expansion.
Permanent databases compare 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
To establish a predictive maintenance program, install monitors at critical locations. Each monitor performs a survey for a reasonable period (a week or month). When a monitor finishes a survey, it downloads and saves data as well as automatically resets to perform subsequent surveys. Multiple databases collected over a year or longer provide engineers with a history of plant power operations or utility consumption. Continuous tracking of changes in power 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.
Full-disclosure monitors capture values much lower than conventional monitors by recording the underlying quiescent data that indicates incipient problems as well as severe events.
The system measures complete power reliability in terms of 100% availability or uptime. So how do you prevent disruption and damage and get advance warning of impending problems? Power monitors collect large volumes of data, and you must analyze this data before you can understand a 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.
Full-disclosure monitors are available for portable or embedded (permanently installed) applications. Only these types of systems capture and analyze the critical information necessary to implement an effective predictive maintenance program for a facility's electrical distribution system.