<p>This report is a degree project performed at Freudenberg Household Products AB, (FHP). </p><p>The degree project comprises measurement and analysis of the power net at FHP Basproduction. The content is divided between one theory-part, one document- part with measurements and also conclusions and a list of measures to be taken. </p><p>During the project the purpose and restriction change from a quality investigation to only concentrate on harmonics and finding the reason why they exist, and also to find a solution to the problem with harmonics. </p><p>The measurements shows that the power net contains harmonics of different order and intensity. High harmonic rate is found under the transformer T-7. </p><p>The problem with harmonics was not known earlier and therefore it can be assumed that there are more built-in frequency converters without filter in pumps, compressors and machines in the whole net. After a number of measurements one can suppose that some parts of the FHP power net is unstable. In an unstable weak power net frequency converters produce a large number of harmonics. In all the cases where large numbers of harmonics have been detected the trace has ended in a power central where a pump, compressor or heating element is. </p><p>Worth to be noticed is that under the same transformer there are strip lights, converters and control electronics. </p><p>The conclusion is that measures against harmonics are possible and necessary to do in most cases. The measures should be made local, as close to the disturbing object as possible, to stop the disturbance to get out in the net. The aim is that the current should stay sinus. </p><p>The purpose with the project could not be fulfilled because the report do not tell about how serious the high number of current harmonics are for running the factory. The opinion is that the harmonics should be reduced to a lower level.</p>

This report is a degree project performed at Freudenberg Household Products AB, (FHP). The degree project comprises measurement and analysis of the power net at FHP Basproduction. The content is divided between one theory-part, one document- part with measurements and also conclusions and a list of measures to be taken. During the project the purpose and restriction change from a quality investigation to only concentrate on harmonics and finding the reason why they exist, and also to find a solution to the problem with harmonics. The measurements shows that the power net contains harmonics of different order and intensity. High harmonic rate is found under the transformer T-7. The problem with harmonics was not known earlier and therefore it can be assumed that there are more built-in frequency converters without filter in pumps, compressors and machines in the whole net. After a number of measurements one can suppose that some parts of the FHP power net is unstable. In an unstable weak power net frequency converters produce a large number of harmonics. In all the cases where large numbers of harmonics have been detected the trace has ended in a power central where a pump, compressor or heating element is. Worth to be noticed is that under the same transformer there are strip lights, converters and control electronics. The conclusion is that measures against harmonics are possible and necessary to do in most cases. The measures should be made local, as close to the disturbing object as possible, to stop the disturbance to get out in the net. The aim is that the current should stay sinus. The purpose with the project could not be fulfilled because the report do not tell about how serious the high number of current harmonics are for running the factory. The opinion is that the harmonics should be reduced to a lower level.

The majority of all power cuts that affects individuals and communities are caused by earth faults on the power transmission lines at 10kV and 20kV level [1]. If these power cuts could be eliminated, less disturbances and interrupts would lead to large amounts of money savings. Swedish Neutral has developed such a protection system. When an earth fault occurs power is injected into the neutral point of the transformer. The RCC (Residual Current Compensation) protection calculates a compensation current exactly 180 degrees out of phase to the fault current. Doing this, the voltage at the fault location becomes very close to zero, without affecting the power transmission. The protection system can only compensate automatically for the fundamental frequency (50Hz), and manually for the 3rd, 5th, 7th and 9th harmonics. In most cases, when the harmonics are very small it is not necessary to compensate for them. There are though cases when compensation for the harmonics is necessary. This thesis focuses on finding the best method to extract the content of a sampled signal regarding both simplicity and speed. Both amplitude and phase of each harmonic must be calculated. Is the proposed method suitable for the current computer system and how can it easily be implemented. Because the fundamental frequency is known and the harmonics are all multiples of the fundamental frequency it makes the task less complex. It is not necessary to use the FFT algorithm. The DFT can be calculated using correlation. Both phase and amplitude can be calculated very precisely with few samples and not so many computer operations.

<p>The majority of all power cuts that affects individuals and communities are caused by earth faults on the power transmission lines at 10kV and 20kV level [1]. If these power cuts could be eliminated, less disturbances and interrupts would lead to large amounts of money savings.</p><p>Swedish Neutral has developed such a protection system. When an earth fault occurs power is injected into the neutral point of the transformer. The RCC (Residual Current Compensation) protection calculates a compensation current exactly 180 degrees out of phase to the fault current. Doing this, the voltage at the fault location becomes very close to zero, without affecting the power transmission.</p><p>The protection system can only compensate automatically for the fundamental frequency (50Hz), and manually for the 3^rd, 5^th, 7^th and 9^th harmonics. In most cases, when the harmonics are very small it is not necessary to compensate for them. There are though cases when compensation for the harmonics is necessary.</p><p>This thesis focuses on finding the best method to extract the content of a sampled signal regarding both simplicity and speed. Both amplitude and phase of each harmonic must be calculated. Is the proposed method suitable for the current computer system and how can it easily be implemented.</p><p>Because the fundamental frequency is known and the harmonics are all multiples of the fundamental frequency it makes the task less complex. It is not necessary to use the FFT algorithm. The DFT can be calculated using correlation. Both phase and amplitude can be calculated very precisely with few samples and not so many computer operations.</p>

When aluminium profiles are manufactured, defects may arise, especially when theprofiles are manufactured through extrusion. During the extrusion process, thesedefects occur on parts of the extruded material because of contaminates that needto be found.The goal of the project is to examine two different types of methods that aresuited for aluminium profiles in the category of non-destructive testing (NDT). Thetwo different methods are non-linear ultrasonic methods called Higher Harmonicsand Non-linear Wave Modulation Spectroscopy. The method that works should thenalso be implemented in a fixture. Of these two methods Higher Harmonics showedthe most promising results by identifying which profile has defects and this methodwas also more appropriate to implement in a fixture.The Higher Harmonics method utilizes two transducers, one as an emitter to thesystem and another as a receiver. When the signal from the emitter passes throughthe non-linearities, which are the defects, and propagates to the receiver the signalcan be inspected on an oscilloscope. The received signal is then transformed to thefrequency domain and if there were defects harmonics should be generated. If thereare many harmonics and the magnitude is high, defects are present.A fixture was also designed to work with the Higher Harmonics method usingprofile struts that are easy to connect to a framework. The fixture worked by raisingand lowering the two transducers which have been built into a probe. The emittingprobe was connected to a signal generator and the receiving probe was connected toan oscilloscope. This measuring station did the measurement more consistent andaccurate than before. The most interesting result that was found in the experimentswas that localization of defects could be found. / Vid tillverkning av aluminiumprofiler kan vissa särskilda defekter uppstå när pro-filerna tillverkas genom extrudering. Under extruderings processen, uppstår dessadefekter på delar av det extruderade materialet på grund av föroreningar och måstehittas.Målet för projektet är att undersöka två olika typer av metoder som är lämpligaför aluminiumprofiler i kategorin oförstörande provning (OFP). De två olika metodernaär olinjära ultraljudsmetoder som kallas Övertoner och Icke-linjär Vågmodulation.Metoden som fungerar bäst bör då också implementeras i en fixtur. Av dessa tvåmetoder visade Övertoner mest lovande resultat genom att kunna identifiera vilkenprofil som var defekt och denna metod var också lämpligare att bygga en fixtur till.Metoden med Övertoner använder två givare, en som sändare till system och enannan som mottagare. När signalen från sändaren passerar olinjäriteterna, som ärdefekterna, och signalen färdas till mottagaren kan den inspekteras på ett oscilloskop.Den mottagna signalen omvandlas sedan till frekvensdomän och om det fanns defek-ter bör övertoner genereras. När defekter är närvarande finns det många övertoneroch magnituden är hög.En fixtur utformades också för att fungera med metoden Övertoner genom attanvända profilstag som är lätta att ansluta till ett ramverk. Fixturen fungeradegenom att höja och sänka de två givarna som har byggts in i en probe. Sändarproben är ansluten till en signalgenerator och den mottagande proben är ansluten tillett oscilloskop. Denna mätstation gjorde mätningen mer konsekvent och noggrannän tidigare mätningar. Det mest intressanta resultatet som framkom i experimentenvar att lokalisering av defekter kunde konstateras.