Danfoss VLT AutomationDrive FC 300 Instruction Manual

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Danfoss VLT AutomationDrive FC 300 Instruction Manual Manual pdf 37 page image

3.7 Additional Connections3.7.1 Mechanical Brake ControlIn hoisting/lowering applications, it is necessary to be able to control an electro-mechanical brake:• Control the brake using any relay output or digital output (terminal 27 or 29).• Keep the output closed (voltage-free) as long as the adjustable frequency drive is unable to ‘support’ the motor, such as when the load is tooheavy, for example.• SelectMechanical brake control [32] in par. 5-4* for applications with an electro-mechanical brake.• The brake is released when the motor current exceeds the preset value in par.2-20Release Brake Current.• The brake is engaged when the output frequency is less than the frequency set in par.2-21Activate Brake Speed [RPM]or par.2-22ActivateBrake Speed [Hz], and only if the adjustable frequency drive carries out a stop command.If the adjustable frequency drive is in alarm mode or in an overvoltage situation, the mechanical brake immediately cuts in.3.7.2 Parallel Connection of MotorsThe adjustable frequency drive can control several parallel-connectedmotors. The total current consumption of the motors must not exceedthe rated output current I M,N for the adjustable frequency drive.NOTE!Installation with cables connected in a common joint,as in the illustration below, is only recommended forshort cable lengths.NOTE!When motors are connected in parallel, par. 1-29Au-tomatic Motor Adaptation (AMA) cannot be used.NOTE!The electronic thermal relay (ETR) of the adjustablefrequency drive cannot be used as motor protection forthe individual motor of systems with parallel-connec-ted motors. Provide further motor protection with, forexample, thermistors in each motor or individual ther-mal relays (circuit breakers are not suitable for pro-tection).Problems may arise at start and at low RPM values if motor sizes are widely different because small motors' relatively high ohmic resistance in the statorcalls for a higher voltage at start and at low RPM values.VLT®AutomationDrive FC 300 InstructionManual 3 How to InstallMG.33.AC.22 - VLT® is a registered Danfoss trademark 3-273