Information about Power Quality
Power quality is a term used to describe electric power that motivates an electrical load and the load's ability to function properly with that electric power. Without the proper power, an electrical device (or load) may malfunction, fail prematurely or not operate at all. There are many ways in which electric power can be of poor quality and many more causes of such poor quality power.
The electric power industry is in the business of electricity generation (AC power), electric power transmission and ultimately electricity distribution to a point often located near the electricity meter of the end user of the electric power. The electricity then moves through the distribution and wiring system of the end user until it reaches the load. The complexity of the system to move electric energy from the point of production to the point of consumption combined with variatons in weather, electricity demand and other factors provide many opportunities for the quality of power delivered to be compromised.
While "power quality" is a convenient term for many, it is actually the quality of the voltage, rather than power or electric current, that is actual topic described by the term. Power is simply the flow of energy and the current demanded by a load is largely uncontrollable. Nevertheless the relationship between the concepts of "voltage quality" and energy quality is unknown.
Ideally electric power would be supplied as a sine wave with the amplitude and frequency given by national standards (in the case of mains) or system specifications (in the case of a power feed not directly attached to the mains) with an impedance of zero ohms at all frequencies.
No real life power feed will ever meet this ideal. It can deviate from it in the following ways (among others):
An uninterruptible power supply can be used to switch off of mains power if there is a transient (temporary) condition on the line. However, cheaper UPS units create poor-quality power themselves, akin to imposing a higher-frequency and lower-amplitude sawtooth wave atop the sine wave.
A surge protector or simple capacitor or varistor can protect against most overvoltage conditions, while a lightning arrestor protects against severe spikes.
Electronic filters can remove harmonics.
Meier, Alexandra von (2006). . John Wiley & Sons, Inc.. ISBN 978-0-471-17859.
Heyden, G.T. (1991)). Electric Power Quality. Stars in a Circle Publications. Library Of Congress 621.3191.
Bollen, Math H.J. (2000). . New York: IEEE Press. ISBN 0-7803-4713-7.
Sankaran, C. (2002). Power Quality. CRC Press LLC. ISBN 0-8493-1040-7.
When electric current flows in a circuit with resistance, it does work.
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The electric power industry is in the business of electricity generation (AC power), electric power transmission and ultimately electricity distribution to a point often located near the electricity meter of the end user of the electric power. The electricity then moves through the distribution and wiring system of the end user until it reaches the load. The complexity of the system to move electric energy from the point of production to the point of consumption combined with variatons in weather, electricity demand and other factors provide many opportunities for the quality of power delivered to be compromised.
While "power quality" is a convenient term for many, it is actually the quality of the voltage, rather than power or electric current, that is actual topic described by the term. Power is simply the flow of energy and the current demanded by a load is largely uncontrollable. Nevertheless the relationship between the concepts of "voltage quality" and energy quality is unknown.
Introduction
It is often useful to think of power quality as a compatibility problem: is the equipment connected to the grid compatible with the events on the grid, and is the power delivered by the grid, including the events, compatible with the equipment that is connected? Compatibility problems always have at least two solutions: in this case, either clean up the power, or make the equipment tougher.Ideally electric power would be supplied as a sine wave with the amplitude and frequency given by national standards (in the case of mains) or system specifications (in the case of a power feed not directly attached to the mains) with an impedance of zero ohms at all frequencies.
No real life power feed will ever meet this ideal. It can deviate from it in the following ways (among others):
- Variations in the peak or RMS voltage are both important to different types of equipment.
- When the RMS voltage exceeds the nominal voltage by 10 to 80% for 0.5 cycle to 1 minute, the event is called a "swell".
- A "dip" (in British English) or a "sag" (in American English - the two terms are equivalent) is the opposite situation: the RMS volage is below the nominal voltage by by 10 to 90% for 0.5 cycle to 1 minute.
- Random or repetitive variations in the RMS voltage between 90 and 110% of nominal can produce a phenomina known as "flicker" in lighting equipment. Flicker is the impression of unsteadiness of visual sensation induced by a light stimulus on the human eye. A prcise definition of such a voltage fluctuations that produce flicker have been subject to ongoing debate in more than one scientific community for many years.
- Abrupt, very brief increases in voltage, called "spikes", "impulses", or "surges", generally caused by large inductive loads being turned off, or more severely by lightning.
- "Undervoltage" occurs when the nominal voltage drops below 90% for more than 1 minute. The term "brownout" in common usage has no formal definition but is commonly used to describe a reduction in system voltage by the utility or system operator to decrease demand or to increase system operating margins.
- "Overvoltage" occurs when the nominal voltage rises above 110% for more than 1 minute.
- Variations in the frequency
- Variations in the wave shape - usually described as harmonics
- Nonzero low-frequency impedance (when a load draws more power, the voltage drops)
- Nonzero high-frequency impedance (when a load demands a large amount of current, then stops demanding it suddenly, there will be a dip or spike in the voltage due to the inductances in the power supply line)
Power conditioning
Power conditioning refers to conditioning the power to improve its quality.An uninterruptible power supply can be used to switch off of mains power if there is a transient (temporary) condition on the line. However, cheaper UPS units create poor-quality power themselves, akin to imposing a higher-frequency and lower-amplitude sawtooth wave atop the sine wave.
A surge protector or simple capacitor or varistor can protect against most overvoltage conditions, while a lightning arrestor protects against severe spikes.
Electronic filters can remove harmonics.
References
Dugan, Roger C.; Mark McGranaghan, Surya Santoso, H. Wayne Beaty (2003). Electrical Power Systems Quality. McGraw-Hill Companies, Inc.. ISBN 0-07-138622-X.Meier, Alexandra von (2006). . John Wiley & Sons, Inc.. ISBN 978-0-471-17859.
Heyden, G.T. (1991)). Electric Power Quality. Stars in a Circle Publications. Library Of Congress 621.3191.
Bollen, Math H.J. (2000). . New York: IEEE Press. ISBN 0-7803-4713-7.
Sankaran, C. (2002). Power Quality. CRC Press LLC. ISBN 0-8493-1040-7.
For delivered electrical power, see .
Electric power is defined as the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt.When electric current flows in a circuit with resistance, it does work.
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electrical power industry provides the production and delivery of electrical power (electrical energy), often known as power, or electricity, in sufficient quantities to areas that need electricity through a grid.
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Electricity generation is the first process in the delivery of electricity to consumers. The other processes are electric power transmission and electricity distribution which are normally carried out by the electrical power industry.
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Real power (P) Reactive power (Q) Complex power (S) ; |S|, the modulus of complex power, is referred to as apparent power.
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Electric power transmission, a process in the delivery of electricity to consumers, is the bulk transfer of electrical power. Typically, power transmission is between the power plant and a substation near a populated area.
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Electricity distribution is the penultimate stage in the delivery (before retail) of electricity to end users. It is generally considered to include medium-voltage (less than 50 kV) power lines, electrical substations and pole-mounted transformers, low-voltage (less than 1000 V)
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An electric meter or energy meter is a device that measures the amount of electrical energy supplied to a residence or business. These are customers of an electric company.
The most common type is more properly known as a (kilo)watt-hour meter or a joule meter.
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The most common type is more properly known as a (kilo)watt-hour meter or a joule meter.
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Electric current is the flow (movement) of electric charge. The SI unit of electric current is the ampere (A), which is equal to a flow of one coulomb of charge per second.
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Definition
The amount of electric current (measured in amperes) through some surface, e.g...... Click the link for more information.
Energy quality the contrast between different forms of energy, the different trophic levels in ecological systems and the propensity of energy to convert from one form to another.
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The term compatibility may refer to:
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- In biology:
- Blood type compatibility
- In computing:
- Pin-compatibility
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sine wave or sinusoid is a function that occurs often in mathematics, physics, signal processing, electrical engineering, and many other fields. Its most basic form is:
which describes a wavelike function of time (t) with
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which describes a wavelike function of time (t) with
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mains usually refers to the general purpose alternating current (AC) electrical power supply (as in “I've connected the appliance to the mains”). The term is not usually used in the United States and Canada.
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Electrical impedance, or simply impedance, describes a measure of opposition to a sinusoidal alternating current (AC). Electrical impedance extends the concept of resistance to AC circuits, describing not only the relative magnitudes of the voltage and current, but also the
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ohm (symbol: Ω) is the SI unit of electrical impedance or, in the direct current case, electrical resistance, named after Georg Ohm.
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Definition
An ohm is the electrical resistance offered by a current-carrying element that produces a voltage drop of one volt when a..... Click the link for more information.
FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. A sequel, titled Amplitude was released in 2003.
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amplitude is a nonnegative scalar measure of a wave's magnitude of oscillation, that is, the magnitude of the maximum disturbance in the medium during one wave cycle.
Sometimes this distance is called the peak amplitude
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Sometimes this distance is called the peak amplitude
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RMS may refer to any of the following:
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People
- Richard M. Stallman (often abbreviated "rms"), veteran software developer and founder of the GNU Project and the Free Software Foundation.
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RMS may refer to any of the following:
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People
- Richard M. Stallman (often abbreviated "rms"), veteran software developer and founder of the GNU Project and the Free Software Foundation.
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electric motor converts electrical energy into mechanical energy. The reverse process, that of converting mechanical energy into electrical energy, is accomplished by a generator or dynamo.
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Lightning is an atmospheric discharge of electricity, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms.[1] A bolt of lightning can travel at a speed of 100000 mph (0 km/h), and can reach temperatures
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FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. A sequel, titled Amplitude was released in 2003.
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harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency. For example, if the frequency is f, the harmonics have frequency 2f, 3f, 4f, etc.
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Dip has many meanings:
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- Dip (dance move), a partner dance move
- Dip (Catalan myth), an evil demonic dog that drinks people's blood
- Dual in-line package, an electronics package with pins lying along two lines
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Spike may refer to:
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Media
Books and magazines
- Spike Magazine
- The Spike, a 1980 novel by Arnaud de Borchgrave
- The Spike, a 1997 novel by Damien Broderick
Film
- Spike of Bensonhurst
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Conditioning may refer to:
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- In probability theory, the use of conditional probability
- In mathematics, the property of a matrix as "well-conditioned" or "ill-conditioned"; see condition number
- In cosmetics, hair conditioning
- Air conditioning
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uninterruptible power supply (UPS), also known as an uninterruptible power source or a battery backup is a device which maintains a continuous supply of electric power to connected equipment by supplying power from a separate source when utility power is not
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Transience means passing with time. Something which has the property of transience is said to be transient, or often simply a transient or transient state.
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amplitude is a nonnegative scalar measure of a wave's magnitude of oscillation, that is, the magnitude of the maximum disturbance in the medium during one wave cycle.
Sometimes this distance is called the peak amplitude
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Sometimes this distance is called the peak amplitude
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The sawtooth wave (or saw wave) is a kind of non-sinusoidal waveform. It is named a sawtooth based on its resemblance to the teeth on the blade of a saw.
The usual convention is that a sawtooth wave ramps upward as time goes by and then sharply drops.
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The usual convention is that a sawtooth wave ramps upward as time goes by and then sharply drops.
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surge protector is an appliance designed to protect electrical devices from voltage spikes. Surge protectors attempt to regulate the voltage supplied to an electric device by either blocking or shorting to ground voltage above a safe threshold.
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