What Is Power Quality And Why Do I Need A Power Quality Analyzer?

The reliability and cost of any electrical systempower of "harmonics". The concept of harmonics is a
depends greatly on the quality of the power suppliedbit more difficult to understand than demand and
to and consumed by the system. Poor power qualityconsumption. Harmonics are a result of non-linear loads
may result in improper function, overheating,that cause irregular spikes and dips in voltage and
accelerated wear and tear, falsely tripped circuitcurrent on an electrical system.
breakers and, in some cases, hazardous conditions.The power provided by utility companies is delivered in
With the introduction of new electronic technologiesthe form of a constant voltage AC (Alternating
over the last several decades, the world has placedCurrent) and takes the shape of a sine wave. Ohms
new and more complex demands for clean andlaw says the amount of current used by an electrical
reliable power.device depends on the load (inductance) of that
Measuring Power Quality typically involves calculatingdevice. If the load varies over time, so will the current.
indicators of power demand, power consumption andHarmonics appear when varying loads (non-linear)
power cleanliness. By measuring demand andcreate short pulses of current that deform the supplied,
consumption, consumers can identify cost centers insinusoidal current waveform, creating an arbitrary
their electrical infrastructures as well as engineer thewaveform.
electrical infrastructure required to meet thoseYou can think of an arbitrary wave as being made up
demands. By measuring cleanliness, consumers areof several fundamental waveforms. The easiest
able to avoid improper function, overheating and aillustration of an arbitrary wave is to picture two people
plethora of other consequences of unclean power.on opposite sides of a pool who create a wave
What is power demand and how do we measure it?towards each other with a pool float. When the
Power demand is the amount of average electricalwaves intersect in the middle, the result is a wave that
energy that is consumed over some period of time byis twice as tall. The resulting wave is made up of two
a device, machine building, etc... Power Qualityfundamental waves.
Analyzers, electronic instruments used to measureThis illustration can be used to explain that happens
indicators of power quality, can average the electricalwhen harmonics occur due to non-linear loads. The
energy and display it in units of "kilowatts". It iscurrent wave becomes deformed from a perfect sine
important that electrical systems are supplied withwave and peaks and valleys create un-clean power.
enough power to meet peak periods of demand.Harmonics can cause devices to overheat, electrical
How does power consumption differ from powerwire ratings to be reduced, motors to prematurely
demand?wear and circuit breakers to falsely trip.
Power consumption, similar to demand, is the "sum" ofPower Quality Analyzers have the ability to identify
electrical usage over time. Power demand reflects anand analyze the fundamental harmonics that make up
instantaneous view of electrical usage, whereas,an arbitrary current wave. Measurements such as
power consumption sums the electrical usage over theTHD (Total Harmonic Distortion) can tell you the
same period of time. Power Quality Analyzerscontribution of harmonic currents to the fundamental
measure consumption in units of watthours (Wh) orcurrent required. Measured as a percentage, 10%
kilowatthours (kWh). Most calculations of the cost ofwould be a reason for concern. Another measurement
power are based on consumption and measured by $called "Crest Factor" will indicate the level of peaking
per kWh.caused by harmonics. The Crest Factor is a ratio of
Once we know power consumption, we can calculatethe Peak Value / RMS Value, which in a perfect sine
a useful metric called "Power Factor". Power Factor iswave would be 1.414.
a ratio of the actual power used by an electricalChoosing a Power Quality Analyzer
system to the apparent power delivered by the utility.There are a number of different Power Quality
In almost all cases, the actual power used will be lessAnalyzer manufacturers such as Fluke, AEMC, Hioki
than the apparent power delivered because of heatand Extech. Some analyzers are designed to measure
dissipation, frictional loss, work performed and othersingle phase systems while others are for three phase
release of energy by the electrical system.systems. Many PQAs integrate with PCs, have
We can use Power Factor to help us put a price tagenhanced data logging capabilities and can produce
on the amount of work the electrical system isprofessional reports typically requested for power
performing, as well as help us install capacitors andquality applications. Power Quality Analyzers range in
other devices that store real energy to avoid beingprice from $1500 to $6500 with the more expensive
charged for excess apparent power. With a Powerproducts offering greater analysis functionality.
Quality Analyzer, you can calculate the "ReactiveWhatever your application or budget it is important that
Compensation", the amount of capacitive valuepower quality is a factor in the design and
required to correct a low Power Factor.maintenance of your electrical system. In order to
Power cleanliness and the need to understandreduce costs, avoid downtime, and increase the
harmonicsservice life of your system, power quality is a force to
Power cleanliness refers to identifying and freeingbe reckoned with.