Manila Power Technologies Incorporated

IEC 61000-4-30 Class A is an international standard which regulates how an instrument measures and computes various power quality parameters so that the values measured are comparable between different instruments and different brands.In the market there are a number of instruments that claim to comply with IEC 61000-4-30 Class A. However, it has been shown in connection with tests and comparative measurements that only a few of these instruments fully comply with IEC 61000-4-30 , Class A. Two parameters proved particularly difficult to measure according to the standard: flicker and harmonics.To take flicker as an example, it refers to disturbances within the eye's sensitivity range, which requires that high-frequency disturbances and signals are filtered out. This requires that the instrument is provided with (active) anti-aliasing filter to make sure that anti-aliasing phenomena do not occur and to make sure that no incorrect flicker values are measured.If a measuring instrument is accurate in accordance with Class A it is assumed that the instrument is equipped with an anti-aliasing filter whose cutoff frequency is at 3KHz and signals and noise above that are filtered out. When purchasing an instrument it is of great importance to look very critically at the measurement performance specified in the technical details. For larger purchases it is recommended that you take the help of a test lab, certification institute or university to check the actual measurement performance of the instrument.

The PQ Secure system is a perfect solution for supervision of power quality and disturbances in the power grid. The system is very user-friendly and provides continuous monitoring of all the power quality parameters in the entire network. The system provides quick and easy tracing of different disturbances and at the same time determination of their direction in the network.

Main functionsPower quality monitoringTransient monitoringLoad monitoringStation controlWorks simultaneouslyAutomatic analysisAutomatic generation of reports

The reasons why disturbances arise and occur in the grid are numerous. In order to effectively correct and prevent power quality disturbances and phenomena, it is essential that you know how the actual facts are. By measuring and presenting the data in a transparent manner, one has the ability to quickly obtain a correct basis for making correct decisions.Traditionally, most power quality measurements have consisted in direct fault searching and troubleshooting. Machinery breaks down, lights flash, robots stop, electronic devices stop working. With portable measurements one can often come close to the source of the disturbance and subsequently remedy any faults.However, many industries and utility companies now work proactively with continuous monitoring to detect sources of disturbance and error conditions in the network before the consequences are too far-reaching. They utilize power quality monitoring systems as an "early warning" system, for example to quickly detect intermittent ground faults before they become full-scale failures with downtime and costly production losses.As power quality systems and their analysis capabilities have increasingly become mor powerful, there are opportunities to work with statistics and trends in a way previously not possible. By for example seeing how voltage fluctuations and harmonic levels change on a yearly basis one can get control over how the grid reacts to current levels of planning.In many contexts, it is of great value to get measurements before a specific action or reconstruction of the network and then to follow up with a verification measurement after the changes. Then you can make sure that the changes have had the intended effect, or you can see what impact they have had otherwise.In connection with the wind power expansion and the expansion of other distributed power sources, large-scale changes of the grid occur. To get control over changes in the grid and in order to make sure that new facilities do not entail new disturbances, it has become common for utility companies to invest in continuous monitoring of the grid.

In order to effectively detect and explain the disturbances and phenomena in the grid, the choice of equipment is crucial. There is a wide range of power quality analyzers and systems designed for this purpose. To facilitate the selection of equipment, we want to highlight some issues that may be useful to consider.

Power quality is assessed based on a number of power quality parameters. Today's instruments usually handle the most common parameters such as voltage, current, power, harmonics, voltage dips, flicker and transients. Often it is difficult to say in advance what type of disturbance gives rise to a fault condition. The more different types of disturbances an instrument handles, the more likely it is that one can identify the disturbance, or alternatively to exclude certain types of disturbances.

When investing in systems for continuous power quality monitoring it is important to consider the number of measuring points that should be included in the system. In terms of administration and management you do not want a system with 5, 10 or 100's of meters to take more time to deal with than a system that only includes 1 or 2 meters.As the system grows it needs to be scalable, i.e. it should be possible to analyze multiple meters simultaneously, to centrally configure and administer meters in groups and to automatically download data from meters. It should be easy to get an overview and see how disturbances come up and spread throughout the grid.