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Troubleshooting Electrical Systems
Maintenance and engineering managers have witnessed the tremendous benefits in the last decade from proactive maintenance related to safety, equipment reliability and cost. Many managers have adopted predictive analysis as a part of their strategic planning, and front-line maintenance technicians more frequently use technologies such as infrared imaging to diagnose problems with facility electrical systems.
But infrared technology is only part of the troubleshooting and predictive maintenance arsenal that can help organizations realize these benefits. Increasingly, managers are revisiting their strategies for specifying and using such equipment cost-effectively and taking a closer look at emerging diagnostic technologies.
In addition to infrared imaging, key diagnostic technology enables technicians to measure system performance and power quality, perform submetering, and conduct vibration analysis and ultrasound tests.
Infrared thermography. Infrared technology has advanced from handheld, spot digital temperature measurement to real-time, non-contact-area temperature profile using a thermal-imaging camera. Often, the camera is linked to a computer that scans equipment during normal operation.
In a fraction of a second, the camera produces a heat pattern showing areas in which heat is concentrated and temperature ranges. The computer can show a normal operating heat profile side-by-side to identify changes and severity, as well as to diagnose the probable cause and corrective action.
System-performance monitoring. System-performance monitoring addresses the quantitative aspects of the electrical system. It employs several types of conventional instruments and meters to measure system parameters, such as voltage, amps, rpm, pressure, temperature, Watts, Watt-hours, kilovolt-amps, and power factor. Changes in these readings can signal impending degradation or loss of power supply.
Power-quality monitoring. This type of monitoring addresses the qualitative aspects of the electrical system and employs several types of instruments, including the following:
- Service entrance meters. These units measure power quality from the provider at the service entrance. They log voltage variations, harmonic distortions and power interruptions.
- Fault recorders. Digital fault recorders record waveforms. Detected harmonics can be filtered out, reducing overheating and eliminating need to oversize equipment.
- Power-quality monitoring systems. These systems include meters to measure load characteristics and software to collect data, integrate it, maintain a database, analyze data, and view or print result summaries.
- Energy and power-quality systems. They record waveforms and harmonics for power-quality monitoring. They also include data-collection and analysis software for summarizing and viewing results.
Submetering. For years, maintenance managers have been interested in metering segments of a facility's total electrical demand or critical individual loads. Today, many are expanding submetering to examine power use, continuity and quantitative changes for each part of the system to more accurately and easily identify opportunities for improving reliability, reducing power use and shaving peak loads.
Vibration Analysis. Vibration analyzers measure such indices as vibration amplitude, frequency, velocity and acceleration. Fans, pumps, motors, generators, turbines and other rotating equipment have a baseline vibration signature. A technician using a vibration analyzer can compare current readings to minimum, base measurements, as well as to a severity limit at the maximum allowed.
This process helps the technician identify wear, misalignment or imbalance, log the data, and predict the remaining useful life. Maintenance then can perform the repair and rebalancing in place during regularly scheduled downtime, avoiding possible service interruption and major damage.
Ultrasound. Ultrasound technology detects high-frequency noise inaudible to humans. It is very effective in detecting electrical discharges, such as arcing, tracking and corona. It also detects leaks in boilers, condensers, steam and air systems, and other major energy consumers. One manufacturer saved nearly $80,000 annually by correcting numerous leaks in the air system after a brief ultrasound inspection.
Technology on the Horizon
Successful technology advances related to power performance and quality measurement have encouraged maintenance and engineering managers to pursue other, more advanced technology application.
For example, organizations are exploring new substation monitoring methods, and some tests already have moved into the prototype stage. Conventionally, submetering was used for segmenting energy use and cost. Newer systems include power-quality measurement to enable better understanding and control of loads in each segment of the distribution system.
The Institute of Electrical and Electronic Engineers (IEEE) has chartered a task force to look at data-interchange formats, indices for power-quality assessment, and voltage-sag tolerance for various pieces of sensitive equipment. Data-interchange formats are being standardized, and power-quality indices are being refined. Both developments will improve technicians' ability to analyze trends in one location, as well as to compare one location to another.
Also, adding Web-browser capability enables a system administrator to monitor the system from anywhere using a laptop via the Internet. By logging onto the energy management server's supervisory control system, an administrator can see real-time events, analyze them, and take corrective action, all from a remote location. Response time is significantly decreased.
Systems that enable continuous-power quantity and quality monitoring provide critical real-time information that enable managers and technicians to understand the conditions that precede power declines or interruptions. Armed with this information, electrical system managers not only are in a stronger position to improve reliability. They are also in a better position to cost-justify the need for electrical-equipment upgrades or new capital investment beyond those described here. One successful application of diagnostic monitoring equipment can saved its cost many times over.
Monitoring Upgrades: 5 Steps to Success
A smart approach maintenance and engineering managers might consider for upgrading an existing diagnostic process for electrical systems or installing a new process involves these steps:
1. Identify types and quantities of electrical system components.
2. Sequence the components by criticality.
3. Contract certified providers of diagnostic measuring equipment to determine the electrical system's condition.
4. Use provider reports to decide when to obtain permanent equipment for in-house analysis and when to use contract services.
5. Develop an implementation plan, sequence and timetable.
Before embarking on this approach, managers must determine the degree of management support. Managers will need some initial data for this purpose showing the ways that the organization or other similar institutions or businesses improved their operations and saved money using this approach.
In some instances, the amount of repairs needed in a facility neglected for a long time would be large, more than management is willing or able to spend immediately. But if a facility faces impending major damage, such as to overheated electrical boxes, managers can help the organization save money on higher insurance bills and major equipment replacement by detecting these most critical conditions and alerting executives of the potential results.
— Thomas Westerkamp