POWERQUALITY BY RICHARD P. BINGHAM
Power quality monitor designers and
manufacturers have noticed this trend.
The latest generation of power quality
meters, portable monitors and monitoring systems incorporate features to make
the analysis of existing problems—and
the prevention of future ones—easier and
safer. International standards continue to
evolve to allow for data comparison and
evaluation from different vendors. And,
like much of the electronics industry,
more features and better performance
are available at lower prices.
Most handheld meters are single-phase instruments. Besides real-time
metering functions of voltage, current
and power parameters, many products
incorporate harmonics and other power
quality parameters. Some meters can
log data for hours or days. Others can
provide waveform capture and display.
Rather than just a simple digital multimeter, having a meter with some power
quality capabilities allows for quick measurements to help determine if a more
comprehensive monitoring program is
needed. At prices less than $1,000, every
toolbox should have one.
Traditional power quality monitors
are in their fifth generation. The above
images of the first dedicated monitor
Model 606 Universal Disturbance Ana-
lyzer and the latest HDPQ Xplorer family
from Dranetz illustrate this dramatic
evolution. Screwdriver adjustments for
trigger thresholds of voltage are replaced
by automatic and wizard setups for thou-
sands of parameters. Data output has
evolved from hundreds of feet of ther-
mal paper to gigabytes for display on
touchscreens. And now, the data can be
transmitted to software to compare mul-
tiple sites in automatic detailed reports.
The large screens provide a clear picture
of waveform and trending data without
having to download the information to a
PC. Providing answers to certain power
quality questions helps the less knowledgeable user determine what tripped
their adjustable-speed drive offline. With
low-cost GPS modules, time accuracies
across portable units can be in the sub-cycle range, aiding in the finger pointing.
User safety also is an important factor in product design by AEMC, Dranetz,
Extech, Fluke, Hioki, Ideal Industries,
Megger, PMI, PSL and others. Voltage
inputs are generally rated for CAT III,
1,000 volts (V) and CAT IV, 600V. Current can be measured using flexible
probes that snake around conductors
without the danger of moving them.
Instruments can be put behind the
switchgear panel with the door panels
closed, using communication methods
such as Wi-Fi and Bluetooth to get data
out and adjust settings using laptops, tablets or smartphones.
Permanently installed power quality
monitors incorporate many of the tech-
nical advances of the portable monitors
in sampling rates, storage memory and
accuracy while calculating more parame-
ters than just about anybody needs. While
these systems have been communicating
by wired and wireless methods for years,
the stand-alone systems are becoming less
common. Integration into other manage-
ment systems is the trend. For utilities,
data from revenue meters, protection
relays, digital fault recorders and power
quality monitors all help manage the
smart grid. Facilities incorporate the data
into building management systems that
provide complete facility energy profiles.
Other necessary tools include infrared
or thermal imaging cameras. Thermal
imaging is a key predictive maintenance
tool in the electrical inspection program,
which provides quick safety checks of
energized equipment before beginning
maintenance work to avoid costly service
interruptions and exorbitant equipment
losses. Just like benchmarking and trending power quality data, doing periodic
thermal imaging surveys can pick up
on problems before they become major
issues. By spotting potential issues, the
device helps avoid process interruptions,
loose bolts, degrading contacts, and overloaded transformers, motors and neutral
conductors due to harmonics.
With all of these tools at your disposal, you can help add positively to the
bottom line without having to become a
power quality expert. A little knowledge
can go a long way.
Trends Aren’t Just Fashionable
In monitoring, newer is better
THE IMPORTANCE OF MONITORING the quality of the electrical supply has
increased with the ongoing push to boost uptime, productivity and profits. When carrying out business 24/7, having a process or operational interruption can negatively
affect of the bottom line. If a customer can’t instantly purchase what they want from
one company, a competitor is just a click away. Coupling with this trend, experienced
power quality professionals are becoming fewer and fewer. Once having extensive
power quality departments, utility companies have reallocated personnel or don’t
replace those lost to attrition. With overworked staff who often don’t know Kirchhoff
from Kierkegaard, facility managers have taken on more responsibility for solving
power quality problems.
BINGHAM, a contributing editor for power quality, can be reached at 732.287.3680. PH
Dranetz Model 606 was introduced in 1975.
Model HDPQ came out almost 40 years later.