Power Quality Monitoring

▼Chapter 4Three-phase power capacitorsMain featuresThe main requirements of power capacitors are a long lifespan and a high level of safety. A quadruple safety system for optimumprotection:Selfhealing dielectricDry impregnation (PCB free)Over pressure tear-off fuseIntegrated discharge resistorsThe over pressure tear-off fuse: the main protection elementIf voltage-related, thermal overloads or numerous breakdowns at the end of the lifespan of the capacitor lead to increased self-healingprocesses with the corresponding development of gas, excess pressure builds up in the capacitor. The capacitors are generally equippedwith an over pressure tear-off fuse to avoid the capacitor can bursting.This protection feature consists of nominal break points in the internal connection wires.If there is excess pressure in the capacitor, the cylindrical capacitor casing expands andthe electrical supply to the active capacitor elements is irreversibly interrupted at thenominal break point.▼Attention:This safety principle is only reliably effective within the defined (specified) load andoverload limits.Technical data and limit values for power capacitorsStandards IEC 60831-1+2, EN 60831-1+2UOvervoltage U n + 10% (up to 8 hours each day) / U n + 15% (up to 30 mins each day)maxU n + 20% (up to 5 mins each day) / U n + 30% (up to 1 min each day)Up to 1,3 x IExcess current I n (up to 1,5 x I n combined effects from harmonics,maxovervoltage and capacity tolerance)Inrush current IS Up to 300 x I nLossesApprox. 0.2 Watt per kvarNominal frequency f 50/60 HzCapacity tolerance -5% / +10%Test voltage (terminal/terminal) VTT 2.15 x U n , AC, 10 sTest voltage (terminal/casing) VTC Up to U n ≤ 660 V: 3000 VAC, 10 s, over U n = 660 V: 6000 VAC, 10 sAverage life expectancy t LD(Co) Up to 150 000 hoursEnvironmental temperatureCoolingAir humidity H rel Max. 95 %-25/D; max temp 55 °C; max 24 hour average = 45 °C; max 1 year average = 35 °C;lowest temperature = -40 °CNatural or forced air coolingOperation heightFixing and earthSafetyDischargeHousingProtection classDielectricImpregnationNumber of switching cycles per yearMax. 4000m above sea levelM12 thread bolts on the housing bottomDry technology, over pressure tear-off fuse, selfhealing, maximum permittedfault current 10000A in accordance with UL810 standardDischarge resistorsAluminium can and steel housingIP20, indoor (optional with terminal cover, IP54)Polypropylene filmDryMaximum 5000 switching cycles in accordance with IEC60831121