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.
Institutionen för teknik och naturvetenskap , 2003. , 31 p.