Getting to the Root of PQ Problems
There's a huge variety of power monitors on the market today, most of which do a wonderful job of reporting when and what kind of power anomalies occur in a facility's distribution system, such as surges, sags, transients, and harmonics. But they stop short of identifying the root cause of the problem. That's where the ZM100 Distribution Analysis System from San Jose, Calif.-based Z Meters comes in.
Unveiled at the October 2005 PowerSystems World show in Baltimore, the ZM100 will hit the market in early 2006 with a retail price of about $10,000. It takes voltage and current measurements on all phases and the neutral at the source and at the connected load to identify and locate conditions that can lead to voltage anomalies and power loss, such as loose wires, carbonized contacts, undersized transformers, harmonic loads, parallel loads, and non-linear impedances. Simply put, the ZM100 takes voltage and current readings from two separate points and then calculates the voltage drops and distribution impedances for each phase and neutral.
Moore is a 40-year veteran of the power quality industry and president and CEO of Z Meters — a company he recently formed to launch this new product. Moore also founded and presided over four other companies prior to this endeavor, including Basic Measuring Instruments and Reliable Power Meters (RPM), which he sold to $4 billion conglomerate Danaher in 2003.
For anyone who has ever used a voltmeter, Moore's design may seem fairly simple, but he explains why implementing the concept was more complicated than it sounds. “Somebody could say, ‘Gee, I could do that with two voltmeters, and put a voltmeter here and put a voltmeter there, right?’ Well, the problem you have is that the electricity is always varying subtly, so the voltage varies by small amounts from cycle to cycle,” he says. “You're looking at 1/60 of a second, and your eyes can't follow anything like that. Also, to get accurate data it's necessary to distinguish between the natural supply variations and the differential voltage.”
To design the ZM100, Moore used a hardware platform developed by power quality monitor manufacturer Summit Technology, Inc. for displaying and capturing information. Z Meters modified the hardware with additions such as a neutral-to-ground channel and a proprietary cross-correlation algorithm. “What we do is we take the two signals — one from meter one and one from meter two, and we shift them in time until we're assured they are absolutely in synchronization. In this fashion, the natural supply variations are zeroed out, and a true differential measurement is accomplished,” Moore explains.
The ZM100 incorporates both Bluetooth communication and memory card storage to provide for either wireless transmission or memory card download of collected data to a personal computer. To maximize the amount of relevant data the device can store, truncation and decimation algorithms are used to select and store only data from cycles that contain abnormalities. Once the data has been downloaded to a computer, the ZM100 Windows-based software performs calculations and correlation of the data in order to characterize the distribution system's impedance. Using these results, abnormalities can be identified so that corrective measures can be taken before a power failure occurs.
Bruce Lonie, president of PowerCET, a power quality consultation firm based in Santa Clara, Calif., believes much of the demand for the ZM100 will come from high-tech manufacturing; however, he says Z Meters is going to have to spread the word before the approach catches on. “They'll have to educate people in looking at it [power quality] in a whole new way, because nobody's ever really approached it from this standpoint.”
Lonie's partner Tom Shaughnessy, the vice president of PowerCET, characterizes the ZM100 as a step in a different direction from traditional power monitors, because it's going back toward looking for root causes. For example, when running infrared inspections on circuit breakers, Shaughnessy says it's common to find a hot breaker. Currently, there is no single tool to determine whether the breaker is just hot because it's carrying a load, or if it's hot because it has internal problems. “Right now when I test breakers I make three or four separate measurements to arrive at that data,” Shaughnessy says. “So I would see it as a beneficial tool in that respect.”
Designed for distribution systems in industrial and commercial facilities, Moore says the medical industry — where power reliability is a matter of life and death — has shown an early interest in the product. “Right now, they basically kind of root around to see if they can find out what the element is that's causing the anomaly,” he says. “It's kind of like Easter egg hunting.”
For more information, visit www.zmeters.com.