7.1.6. Closed Loop Drive SystemA drive system consist usually of more elements such as:• Motor• Add(Gearbox)(Mechanical Brake)• FC 302 AutomationDrive• Encoder as feed-back system• Brake resistor for dynamic braking• Transmission• LoadApplications demanding mechanical brake control will usually need abrake resistor.Illustration 7.1: Basic Set-up for FC 302 Closed LoopSpeed Control7.1.7. Programming of Torque Limit and StopIn applications with an external electro-mechanical brake, such as hoisting applications, it is possible to stop the frequency converter via a 'standard' stopcommand and simultaneously activate the external electro-mechanical brake.The example given below illustrates the programming of frequency converter connections.The external brake can be connected to relay 1 or 2, see paragraphControl of Mechanical Brake. Program terminal 27 to Coast, inverse [2] or Coast andReset, inverse [3], and program terminal 29 to Terminal mode 29 Output [1] and Torque limit & stop [27].Description:If a stop command is active via terminal 18 and the frequency converter is not at the torque limit, the motor ramps down to 0 Hz.If the frequency converter is at the torque limit and a stop command is activated, terminal 29 Output (programmed to Torque limit and stop [27]) isactivated. The signal to terminal 27 changes from 'logic 1' to 'logic 0', and the motor starts to coast, thereby ensuring that the hoist stops even if thefrequency converter itself cannot handle the required torque (i.e. due to excessive overload).- Start/stop via terminal 18Par. 5-10 Start [8]- Quickstop via terminal 27Par. 5-12 Coasting Stop, Inverse [2]- Terminal 29 OutputPar. 5-02 Terminal 29 Mode Output [1]Par. 5-31 Torque Limit & Stop [27]- Relay output [0] (Relay 1)Par. 5-40 Mechanical Brake Control [32]FC 300 Design Guide 7. Application ExamplesMG.33.BA.02 - VLT® is a registered Danfoss trademark 1477
