8.1.1 Closed Loop Drive SystemA drive system consist usually of more elements such as:• Motor• Add(Gearbox)(Mechanical Brake)• FC 302• Encoder as feed-back system• Brake resistor for dynamic braking• Transmission• LoadApplications demanding mechanical brake control willusually need a brake resistor.Motor GearboxLoadTransmissionEncoder Mech. brakeBrake resistor130BA120.10Illustration 8.5 Basic Set-up for FC 302 Closed Loop SpeedControl8.1.2 Programming of Torque Limit andStopIn applications with an external electro-mechanical brake,such as hoisting applications, it is possible to stop thefrequency converter via a 'standard' stop command andsimultaneously activate the external electro-mechanicalbrake.The example given below illustrates the programming offrequency converter connections.The external brake can be connected to relay 1 or 2.Program terminal 27 to [2] Coast, inverse or [3] Coast andReset, inverse, and program terminal 29 to [1] Terminalmode 29 Output and [27] Torque limit & stop.Description:If a stop command is active via terminal 18 and thefrequency converter is not at the torque limit, the motorramps down to 0 Hz.If the frequency converter is at the torque limit and a stopcommand is activated, terminal 29 Output (programmed toTorque limit and stop [27]) is activated. The signal toterminal 27 changes from 'logic 1' to 'logic 0', and themotor starts to coast, thereby ensuring that the hoist stopseven if the frequency converter itself cannot handle therequired torque (i.e. due to excessive overload).• Start/stop via terminal 185-10 Terminal 18 Digital Input Start [8]• Quickstop via terminal 275-12 Terminal 27 Digital Input Coasting Stop,Inverse [2]• Terminal 29 Output5-02 Terminal 29 Mode Terminal 29 Mode Output[1]5-31 Terminal 29 Digital Output Torque Limit &Stop [27]• Relay output [0] (Relay 1)5-40 Function Relay Mechanical Brake Control [32]Application Examples VLT® AutomationDrive FC 300 Design Guide, 0.25-75 kW154 MG33BE02 - VLT® is a registered Danfoss trademark88RSPSupply - 1-888-532-2706 - www.RSPSupply.comhttp://www.RSPSupply.com/p-21462-Danfoss-131B8966-VLT-Automation-VT-Drive-VFD-FC301-230V-5-HP.aspx
