The professionals
at Power Quality Inc. have more than 20 years experience in the power quality industry. We
offer engineering services and provide products worldwide.
1. What is Power Quality?
Many answers apply to this simple question. They all
depend on your perspective.
From the utility perspective, Power Quality has
been defined as the parameters of the voltage that affect the customers supersensitive
equipment.
From the power user perspective, Power
Quality may be defined as any electrical parameter or connection that affects the
operation of the equipment. This included all electrical parameters, connections and
grounds, whether the source from the utility, local equipment or other users.
From the Power Quality market or industry
perspective, it is any product or service that is supplied to users or utilities to
measure, treat, remedy, educate engineers or prevent Power Quality issues, problems and
related items.
Interesting note: A survey by
Georgia Power in the mid 1990's revealed that utilities perception is 1% of the Power
Quality problems are caused by the utility. The users perception is the utility is 17% of
the cause. The utility perspective is the customer is 25% of the cause and users
perspective is the customer is 12% of the cause.
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3.
What is the most common Power Quality problem?
Voltage sags are considered the most common Power Quality
problem. These can be caused by the utility or by customer loads. When sourced from the
utility, they are most commonly caused by faults on the distribution system. These sags
will be from 3 to 30 cycles and can be single or three phase. Depending on the design of
the distribution system, a ground fault on 1 phase can cause a simultaneous swell on
another phase.
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4.
What is the second most common Power Quality problem?
A recent survey of Power Quality experts in Arizona, indicates
that 50% of all Power Quality problems are related to grounding, ground bonds, neutral to
ground voltages, ground loops, ground current or other ground associated issues.
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6.
Why has Power Quality only become an issue in recent
years?
Power Quality has been an issue since electrical power was
invented. It has only become a well published issue in recent years because of the loads
it affects. If your favorite TV program is interrupted by the local sewage pump operating
on a Variable Speed drive interfering with it, you are aware of a Power Quality problem.
When the lights blink and your PC reboots, you are aware of a Power Quality problem. The
electrical loads get more sensitive.
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Harmonics are distortions in the AC waveform. These distortions
are caused by loads on the electrical system that use the electrical power at a different
frequency than the fundamental 50 or 60 Hz. An example of such a load is the common PC,
television receiver or any other electronic load.
How
do harmonics affect the electrical system?
In general harmonics cause magnetic portions of the electrical
system to overheat. Such as transformers, line reactors, magnetic relays and power factor
capacitors.
The affect of harmonics
on loads varies a great deal and is dependent on the load itself. Most loads are not
affected by moderate levels of harmonics. Exceptions to this are loads that perform
electrical measurements in the frequency domain of the harmonics.
It requires specialty, measurement equipment to measure, record and diagnosis
harmonic problems. Because most equipment does not specify what level of power quality is
required. Power Quality Inc. offers a service of characterizing all
aspects of Power Quality and determining if it is acceptable to the load.
