Danfoss VLT AQUA Drive FC 202 Design Manual

Also see for VLT AQUA Drive FC 202: Service guide Installation guide Installation guide Operating guide Installation guide

Contents

3.3.6.3 Special EnvironmentsIn areas with medium-voltage transformers clearlydemarcated from other areas, the user decides which typeof environment to classify their facility. The user isresponsible for ensuring the electromagnetic compatibilitynecessary to enable the trouble-free operation of alldevices within specified conditions. Some examples ofspecial environments are shopping centres, supermarkets,filling stations, office buildings, and warehouses.3.3.6.4 Warning LabelsWhen a frequency converter does not conform to CategoryC1, provide a warning notice. This is the responsibility ofthe user. Interference elimination are based on classes A1,A2, and B in EN 55011. The user is ultimately responsiblefor the appropriate classification of devices and the cost ofremedying EMC problems.3.3.7 Use with Isolated Input SourceMost utility power in the United States is referenced toearth ground. Although not in common use in the UnitedStates, the input power may be an isolated source. AllDanfoss frequency converters may be used with isolatedinput source as well as with ground reference power lines.3.3.8 Power Factor CorrectionPower factor correction equipment serves to reduce thephase shift (φ) between the voltage and the current tomove the power factor closer to unity (cos φ). This isnecessary when a large number of inductive loads, such asmotors or lamp ballasts, are used in an electrical distri-bution system. Frequency converters with an isolated DClink do not draw any reactive power from the mainssystem or generate any phase power-factor correctionshifts. They have a cos φ of approximately 1.For this reason, speed-controlled motors do not have totake into account when dimensioning power factorcorrection equipment. However, the current drawn by thephase-correction equipment rises because frequencyconverters generate harmonics. The load and heat factoron the capacitors increases as the number of harmonicgenerators increases. As a result, fit chokes in the power-factor correction equipment. The chokes also preventresonance between load inductances and the capacitance.Converters with cos φ <1 also require chokes in the powerfactor correction equipment. Also consider the higherreactive power level, for cable dimensions.3.3.9 Input Power DelayTo ensure that the input surge suppression circuitryperforms correctly, observe a time delay betweensuccessive applications of input power.Table 3.16 shows the minimum time that must be allowedbetween applications of input power.Input voltage [V] 380 415 460 600Waiting time [s] 48 65 83 133Table 3.16 Input Power Delay3.3.10 Mains TransientsTransients are brief voltage peaks in the range of a fewthousand volts. They can occur in all types of power distri-bution systems, including industrial and residentialenvironments.Lightning strikes are a common cause of transients.However, they are also caused by switching large loads online or off, or switching other mains transients equipment,such as power factor correction equipment. Transients canalso be caused by short-circuits, tripping of circuit breakersin power distribution systems, and inductive couplingbetween parallel cables.EN 61000-4-1 standard describes the forms of thesetransients and how much energy they contain. Theirharmful effects can be limited by various methods. Gas-filled surge arresters and spark gaps provide first-levelprotection against high-energy transients. For second-levelprotection, most electronic devices, including frequencyconverters, use voltage-dependent resistors (varistors) toattenuate transients.3.3.11 Operation with a Standby GeneratorUse back-up power systems, when the continuedoperation is necessary in the event of mains failure. Theyare also used in parallel with the public power grid toachieve higher mains power. This is common practice forcombined heat and power units, taking advantage of thehigh efficiency achieved with this form of energyconversion. When back-up power is provided by agenerator, the mains impedance is usually higher thanwhen power is taken from the public grid. This causes thetotal harmonic distortion to increase. With proper design,generators can operate in a system containing devices thatinduce harmonics.System design consideration with a stand-by generator isrecommended.System Integration Design GuideMG20N602 Danfoss A/S © 09/2014 All rights reserved. 533 3