Power Quality Analyzers from Rishabh Instruments Pvt Ltd

There are quite a few reasons for measuring and analyzing power quality nowadays. Potential interactions between end use equipment and electric distribution system, external electromagnetic interferences, resonant states between electrical circuits and some other factors call for a need to be analyzed in order that harmful consequences can be omitted or prevented. The complete industry shall be benefited with the use of the power quality analysis. Application areas for power quality monitoring: Power quality is of a great importance in all modern environments. -Manufacturing plants -Banks -Hospitals -Telecommunication companies -IT and Data centers -Education and other Public Services -Power distribution -Power generation & any place where electricity is involved…. Power quality can essentially influence a number of important factors like: -Quality of service, -Competitiveness of services and products -Time management -High availability of the electric systems is therefore of extreme essence nowadays. Benefits of power quality analyzing: -By analyzing power quality following benefits can be obtained. -Interferences and failure detection -Non-linear loads with high content of harmonics, loose bus bars, switching problems with capacitor banks and similar problems can essentially decrease availability of electric equipment or electric distribution systems. -Detection of failure/interferences generation points can be easily found with a suitable Power Quality Analyser. -Advanced power resources management and predictive diagnostics -Optimized daily or weekly consumption diagrams can essentially reduce costs for electricity and infrastructure. Reducing electric energy losses, control of peak consumption and improving power factor can bring important savings. -Power Quality Analyser will simplify decision-making. Input power quality evaluation according to EN 50160 -Transients, voltage variations and supply interruptions often come from the supply network and influence operations of internal electrical systems. Loss of data, shorter life span of the electronic equipment, increased rejection level on production lines etc. are consequences of bad quality power supply. -Supply voltage quality can be assessed in accordance with relevant “Power Quality” standards (example: EN 50160). -Advanced Power Quality Analysers will produce “Quality compliance” report which can be used for further negotiations with electro-distribution company if necessary. Proper realization of reactive power compensation results in: •   Lower transmission losses •   Stable network voltage •   Lower electricity costs for end users Distorted signal is analysed with Fast Fourier Transformation (FFT) calculation method.  Basic signal with a fundamental frequency 50/60Hz is reported together with individual harmonic components. There are some representative examples how and when certain harmonics appear. Computers, printers and other small office IT equipment. High 3rd, a bit lower 5th, 7th, 11th and 13th current harmonics are typical for such loads. Variable frequency drives (VFD’s). High harmonic components like 5th, 7th, 11th, 13th, 17th and 19th order.   3rd, 6th, 9th, 12th Harmonics cause high current in a neutral conductor in 3-phase, 4-wire systems. Consequences of high current harmonics •   Harmonics cause circuit breakers tripping at no apparent overload. •   Voltage waveforms to other loads can be distorted and interference can be inductively coupled between power and low-voltage communication lines if they are placed close to each other. •   Harmonics that flows back to the supply network can have various negative effects. In case 5th harmonic is highly present 3-phase inductive motors can experience “torque fight” as this component cause the negative torque that tends to turn the motor backwards. Consequently more power is consumed and the motor gets gradually overheated. •   High harmonics reduce the “transmission” capacity of the supply network, as they do not perform any useful work. •   High neutral conductor currents are also a consequence of high current harmonics. Thus a neutral conductor cross-section has to be larger or there is a significant risk of fire. •   High current harmonics supplied back to the network may influence the harmonics content on the supply voltage, which in the next step result on unwanted current harmonics on the end-user equipment. Preventive and corrective actions •   When purchasing and installing new equipment it is recommended that the “low content THD” is selected. •   Neutral conductor in a 3-phase system has to be sized in respect with current harmonics content as well. It sometimes means the cross-section of the neutral conductor has to be larger than the phase conductor’s. •   In order to limit current harmonics active or passive filters are used. They will damp unwanted harmonics down to acceptable level. Active filters are frequently used together to eliminate harmonics created by variable electronic loads. Their filtering performance adapts automatically based on the existing harmonics spectrum. There are some standard versions and sizes of active and passive filters available on the market. Longer power supply interruptions that can be categorised as unexpected or foreseeable. Consequences of voltage variations •   One of the most obvious phenomena are flickers which describe changing of the illumination intensity as a reflection of a changing voltage level. Flickers are annoying for people.  Fluctuating illumination results in increased tiredness and lower productivity. •   Telecom and data centres with frequent downtimes may experience data loss or even reduced revenue. Voltage spikes can damage computer’s hardware or similar equipment. Events like voltage surges, sags and similar can cause malfunctioning of the equipment and their premature ageing. •   Production lines exposed to considerable voltage fluctuations may generate increased rejection level and have lower productivity. Possible solutions •   Installing UPS systems. These will compensate voltage variations to a certain extent. UPS systems are frequently used as a back-up power supply system in IT, Data and Telecom environments.  Possible drawback of installing UPS systems is that they may generate harmonics. •   Over-voltage protection devices can considerably reduce fatal consequences of over-voltage transients corresponding. They will protect expensive and high-availability systems. •   Analysing internal electrical inventory and their influences on the voltage variations. •   Assessing the input power quality on the connection point in order to prove that supplied voltage complies with relevant standards.   Overheating of a neutral conductor -4-wire three-phase systems that carry high content of current harmonics are often exposed to an overheating of a neutral conductor. It also happens that circuit breakers react without apparent reason. High current harmonics in individual phases namely create asymmetry, which results in increased current in a neutral conductor. -Overheated neutral conductor can create a fire potential. Therefore it is recommended that a current THD is periodically measured and the neutral conductor’s overheating is checked. Situations with current THD>15% are likely to cause increased overheating of a neutral conductor. -Such situations occur where larger number of non-linear loads appears. Possible solutions can go in a direction of increasing a neutral conductor’s diameter, filtering current harmonics to the acceptable level or perhaps splitting existing circuit into several smaller circuits with separate neutral conductors. EN50160 compliance testing: EN50160 is a standard widely used within European community and some other non-European countries and defines and describes the characteristics of the supply voltage concerning: -   Voltage -   Magnitude -   Wave form -   Symmetry of the three phase voltages


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Rishabh Instruments Pvt. Ltd., a 20 year young organization that has built its core competence in manufacturing, design and development of Test and Measuring Instruments and Industrial Control Products on strong fundamentals; in terms of people, infrastructure and financials. The company provides a hands-on, value driven, professional environment with people being its most important asset.

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