Statuskontroll av Paradisskolans elektriska belastning
Power qualityHarmonicsVoltage disturbancesEnergy measurementsGround faultChauvin ArnouxElkvalitetövertonerSpänningsstörningarEnergimätningJordfelChauvin Arnoux
In this thesis is studied the electrical load of Paradisskolan with respect to power quality and energy consumption. The school's owner Trollhättans Tomt AB is also interested to know if they can reduce their costs by changing to smaller meter fuses. A recurring ground fault that?s been recorded from powerpanel A1A has been investigated. The school's equipped with an electrical bonding system, harmonic filters for the third harmonic currents, TN-S system from feeding transformer and groundfault monitoring. Closest to perfect power quality was expected, but the analysis shows a high potential difference between neutral conductor and PE, Protective Earth, conductor, high levels of harmonic voltage, Uthd-values ??of 8-10% during weekdays. It?s over the prescribed limits according to standard. Current harmonics occur in the electrical network but not enough to produce any heating in the neutral conductor that is well dimensioned. Power curves show normal values ??and the power factor is approximately 0.9. Voltage unbalance and voltage fluctuations show good values.Energy can be saved by adjusting the time for the ventilation room controlled by cabinet AS1 and if it?s possible to turn off parts of the exterior lighting at night. Apparent power and currents which are measured at high load shows that the meter fuses are not possible to change to smaller ones.The Power quality problems are examined and they are derived in part to the harmonic filter, which is connected in series with the incoming neutral conductor. The potential difference occurs only with the harmonic filter connected because of the difference in impedance between neutral and PE. The level of Uthd is reduced when the filter is turned off.The harmonic filter should be switched off to reduce Uthd to below prescribed limit values and to remove the potential difference between neutral and PE conductor. The ground fault is derived to a cold store room in a separate building. It's the buildings lighting installation that creates the groundfault. Otherwise, the network is well dimensioned and the power quality good.