1.4.3 Block Diagram of the AdjustableFrequency DriveFigure 1.3 is a block diagram of the adjustable frequencydrive's internal components. See Table 1.2 for theirfunctions.Figure 1.3 Adjustable Frequency Drive Block DiagramArea Title Functions1 Line power input• 3-phase AC line power supplyto the adjustable frequencydrive.2 Rectifier• The rectifier bridge convertsthe AC input to DC current tosupply inverter power.3 DC bus • Intermediate DC bus circuithandles the DC current.4 DC reactors• Filter the intermediate DCcircuit voltage.• Prove line transientprotection.• Reduce RMS current.• Raise the power factorreflected back to the line.• Reduce harmonics on the ACinput.5 Capacitor bank• Stores the DC power.• Provides ride-throughprotection for short powerlosses.6 Inverter• Converts the DC into acontrolled PWM AC waveformfor a controlled variableoutput to the motor.7 Output to motor • Regulated 3-phase outputpower to the motor.Area Title Functions8 Control circuitry• Input power, internalprocessing, output, and motorcurrent are monitored toprovide efficient operationand control.• User interface and externalcommands are monitored andperformed.• Status output and control canbe provided.Table 1.2 Legend to Figure 1.31.4.4 Enclosure Types and Power RatingsFor enclosure types and power ratings of the adjustablefrequency drives, refer to chapter 8.9 Power Ratings, Weightand Dimensions.1.5 Approvals and CertificationsMore approvals and certifications are available. Contact thelocal Danfoss partner. Adjustable frequency drives ofenclosure type T7 (525–690 V) are not certified for UL.The adjustable frequency drive complies with UL508Cthermal memory retention requirements. For moreinformation, refer to the section Motor Thermal Protectionin the product specific design guide.1.6 DisposalDo not dispose of equipment containingelectrical components together withdomestic waste.Collect it separately in accordance withlocal and currently valid legislation.Introduction Instruction ManualMG33AP22 Danfoss A/S © Rev. 09/2014 All rights reserved. 71 1