Power Management

How Today’s Meters Make Power Quality Data Easier To Understand

Today’s power-quality metering devices can capture data on issues ranging from transients and surges to harmonics and power interruptions – but that raw data, alone, might not be useful to the personnel charged with maintaining a facility’s electrical system. New products address this challenge with embedded intelligence to show trends and alerts, with at-a-glance displays designed to meet the needs of many different staff members.

As I described in my last post, “Power Quality: Measuring to Manage,”continuous power-quality monitoring is the best way to both maintain current equipment performance and support a facility’s continuous improvement efforts and to boost operation’s bottom line. The new displays make such programs easier in a number of ways. For example, a trend graph, as illustrated in Figure 1, can provide clear indication of many long-term, steady-state power-quality disturbances over time. Facility staff can easily see if recommended limits on harmonics, power factor or other potential problem areas have been exceeded.

Figure 1-Analysis of continuous power quality disturbances.

Figure 1-Analysis of continuous power quality disturbances.

Short-term disturbances, such as voltage sags, swells, transients and interruptions are represented in a more snapshot fashion, using a variety of statistical widgets, charts and counters, as shown in Figure 2.

Figure 2-Analysis of power quality events.

Figure 2-Analysis of power quality events.

Such a presentation can offer a range of views – from a pie-chart-style breakdown of the kinds of power-quality events a facility might be experiencing to bar charts comparing the impact of events either upstream or downstream of the measured location.

Several new-to-market Schneider Electric meters are taking this graphical approach a step further. The systems feature a simplified user interface that uses the green/yellow/red visual metaphor familiar to just about any automobile driver to indicate both short- and long-term power quality issues. In this application, green obviously indicates no critical issues with the characteristic being measured, while yellow and red indicators suggest performance is approaching or exceeding limits outlined in related electrical codes and standards.

What is G-Y-R?

What is G-Y-R?

The green/yellow/red approach solves a common problem of those whose job it is to monitor and maintain power systems: the wide diversity of potential power-quality problems and their related metrics and applicable standards can be overwhelming. This methodology converts this multitude of taxonomies into meaningful, unified and easy-to-understand indicators for each specific power-quality characteristic.

The new systems also are able to calculate an overall power-quality index that amalgamates the data on individual measured characteristics into a 0%-100% rating – kind of like a report card for a single metered connection or an entire facility.

In my next post, I’ll cover how this easily accessible data can be used to develop solutions targeted to a facility’s specific needs. You can learn more about green, yellow and red indicators for effective power-quality management in this Schneider Electric white paper. And you can check out Schneider Electric solutions, such as PowerLogic PM 8000 and StruxureWare power-management software.


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