Use of the Power Line Communication System (PLC) at Low Voltage (0.4 kV)
Noisy Electrical Networks – Introducing a New Concept at Power Quality
István SZÉN1, Ervin RÁCZ (PhD)1
1 Institute of Power Engineering
Kandó Kálmán Faculty of Electrical Engineering, Óbuda University
Bécsi út 94-96A, 1039 Budapest (Hungary)
Installing of these new energy sources new challenges will be outcroped. New challenges must be solved by
electrical engineers and other professionals. For example, it is important to know that how these small power plants
connect to the central power system. Parallel to the advantages of the small systems they can introduce
significant electric noises in the central electric system. Figure 3. shows an example how a mini solar cell power
supply system connect to a 0.4 kV main central electric line.
PLCs are very sensitive for electric noises.
Unfortunately, high frequency electric noises can affect their operations. The power line communication works at
frequency range of 9 – 95 kHz (CENELEC A-band). This frequency range is endangered by electric noises.
Another important factor is: the PLCs cannot be substituted by other parts. They must be protected!
The aim of the present research work was mapping the noise effect on PLCs. In order to investigate the role of
the high frequency noises on PLC operation, some test measurements on PLCs with different inverters have
been made. Figure 4. presents the actual experimental setup used for the measurements.
Measurements were started at flow meter installed closest to the data concentrator. This flow meter was installed 50
meters far from the data concentrator device. Next measurements were made 200 meters, than 150 meters
and than another 150 meters far at different direction from the data concentrator, respectively.
Fig. 12.: Measurement data shows significant noise level at PLC region in case of measurement at household #2.
Carriers can not be observed due to strong noise level. Finally, communication resulted incorrect transmission of
information and interrupted connection (measurement position #4). 
noise diagram showed fluctuations causing statistical errors. Signal – noise ratio depends on the daylight time period.
For example: afternoons and night times stronger noises were detected than in the morning. Weekends and in the
night periods noise signals were significantly stronger influecting read out cycle of flow meters.